MediaWiki - User contributions [en]

Overview of Groundwater in Africa

2023-11-28T14:26:29Z

KirstyUpton:

[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Additional resources | Resource pages ]] >> Overview of groundwater resources and hydrogeological environments in Africa

Please cite page as: Africa Groundwater Atlas. 2019. Overview of Groundwater in Africa. British Geological Survey. Accessed [date you accessed the information]. ''Weblink''.

==Groundwater in Africa==

Groundwater has many advantages as a source of safe, sustainable water in Africa. It is particularly suited to regions with large rural populations, where demand for water is dispersed across large areas. The main advantages and limitations of groundwater as a water resource are summarised below.

====Advantages of groundwater as a water resource in Africa====

*Groundwater can be found in most environments, at least enough to provide small domestic supplies. It is therefore usually available close to the point of demand.
*Groundwater usually has excellent natural water quality and is usually suitable for potable use with no prior treatment.
*Groundwater is naturally more protected from contamination than surface water/
*Groundwater provides large volumes of natural water storage. Seasonal variations in amount or quality aren't usually significant, so that groundwater is more drought resistant than surface waters.
*Groundwater lends itself well to principles of community management. It can be developed incrementally, often at relatively low cost/initial capital investment.

====Limitations of groundwater as a water resource in Africa====

*In some hydrogeological environments, considerable investment is needed to locate and develop suitable sites for groundwater abstraction - dug wells, drilled boreholes or improved springs.
*In some hydrogeological environments, there can be natural groundwater quality problems - such as iron, fluoride or arsenic.
*As human development increases, the threat of groundwater pollution increases, and there is a greater need for awareness of, and action on, groundwater and aquifer protection.
*Groundwater can be vulnerable to over-abstraction, particularly in low productivity aquifers and/or as water demand and the ability to abstract large volumes of water both grow. Long term changes in rainfall patterns can also impact on groundwater recharge and renewal.
*As overall water supply coverage increases, more hydrogeologically difficult areas can remain unserved, and they become more costly to develop.

===Hydrogeological environments in Africa===

Groundwater is found in [https://en.wikipedia.org/wiki/Aquifer '''aquifers'''] - underground layers of water-bearing rock or sediment that contain groundwater. Aquifers are very different in different places, depending on the type and history of rock or sediment of which they are made - ie, depending on their [https://en.wikipedia.org/wiki/Geology '''geology'''] and their weathering history.

How and where groundwater occurs depends primarily on '''geology''' (including weathering) and on '''rainfall''' (both current and historic). The interaction between these factors gives rise to complex '''hydrogeological environments''', with countless variations in the quantity, quality, ease of access to and renewability of groundwater resources. Because the [https://en.wikipedia.org/wiki/Hydrogeology hydrogeology] - of different hydrogeological environments - in other words, how groundwater exists and behaves - is very different, it is often necessary to use different methods to find, abstract and manage groundwater in different environments. A good understanding of the hydrogeological environment is essential in order to successfully develop groundwater resources.

Africa is hugely diverse in its geology, climate and hydrology. As a result, the hydrogeology of Africa is also hugely variable. But at a continental scale, there are only four main types of '''hydrogeological environment''' (or '''aquifer type''') - shown in the map, below:

*'''basement''' aquifers;
*'''volcanic''' aquifers;
*'''consolidated sedimentary''' aquifers (which can be dominated by either fracture and/or intergranular flow); and
*'''unconsolidated sedimentary''' aquifers.

A detailed description of these environments is in [https://nora.nerc.ac.uk/501047/ MacDonald and Davies (2001)]; and a summary is below.

[[File:Africa_Hgcl_Envs.png|thumb| 400px|center| The main hydrogeological environments in Africa]]

====Basement aquifers====

Crystalline basement rocks of Precambrian age underlie much of Africa. They form low productivity aquifers that provide small rural water supplies for tens, if not hundreds, of millions of people. Groundwater occurs where the rocks have been significantly weathered and/or in fracture zones, most of which are usually shallower than a few tens of metres depth. Borehole and well yields are generally low, but usually sufficient for rural demand.

<center>

<div><ul>

<li style="display: inline-block;"> [[File:weathered basement.png| 300 px| thumb |left | Groundwater occurrence in a weathered basement aquifer]] </li>

</ul></div>

</center>

====Volcanic aquifers====

Volcanic rocks underlie a small but significant proportion of Africa's land area, and are an important water source for tens of millions of people, many of whom live in the drought stricken areas of the Horn of Africa. Groundwater in volcanic aquifers is found within palaeosoils and fractures between lava flows. Yields can be high, and springs are important sources in highland areas.

<center>

<div><ul>

<li style="display: inline-block;"> [[File:volcanic_aquifers.png| 300 px| thumb| right| Groundwater occurrence in a volcanic rock aquifer]] </li>

</ul></div>

</center>

====Consolidated sedimentary aquifers====

Consolidated sedimentary rocks underlie around one third of Africa's land area, and can form thick, highly productive aquifers. The most significant aquifers are sandstones and limestones, which can be exploited for large urban as well as rural supplies. Mudstones however, which account for about 65% of all sedimentary rocks in Africa, contain little groundwater, and careful study is required to develop groundwater supplies from mudstones.

<center>

<div><ul>

<li style="display: inline-block;"> [[File:sedimentary_aquifers.png| 300 px| thumb| left | Groundwater occurrence in a consolidated sedimentary aquifer]] </li>

</ul></div>

</center>

====Unconsolidated sedimentary aquifers====

Unconsolidated sediments directly underlie much of Africa, and are extremely important for both rural and urban water supplies. Unconsolidated sands and gravels occur in most river valleys throughout Africa, and in many coastal areas. These deposits are often highly permeable and can store large volumes of groundwater at shallow depths, which is easy to exploit by traditional shallow wells and boreholes.

<center>

<div><ul>

<li style="display: inline-block;"> [[File:riverside_alluvium.png| 300 px| thumb| right| Groundwater occurence in unconsolidated valley alluvium]] </li>

</ul></div>

</center>

===More Information===

More information on geology and aquifer characteristics across Africa can be found in these [[Additional resources | resource pages]]: [[Geology | geology]]; [[Hydrogeology Map | hydrogeology map]]; and [[Aquifer properties| aquifer properties]]. More detailed information on aquifers in each country can be found in the [[Hydrogeology by country | country pages]].

Maps summarising the hydrogeology of Africa:
[https://www2.bgs.ac.uk/groundwater/international/africanGroundwater/maps.html Quantitative Groundwater Maps for Africa]

MacDonald, A.M. & Davies, J. 2000. [https://nora.nerc.ac.uk/501047/ A brief review of groundwater for rural water supply in sub-Saharan Africa]. British Geological Survey Report WC/00/033.

MacDonald, A.M., Bonsor, H.C., Ó Dochartaigh, B.É. & Taylor, R.G. 2012. [https://iopscience.iop.org/article/10.1088/1748-9326/7/2/024009;jsessionid=18D8D7F69C3ACBEED0D7494F46850BD6.c1 Quantitative maps of groundwater resources in Africa]. Environmental Research Letters 7(2).

MacDonald, A.M. & Calow, R.C. 2009. [https://nora.nerc.ac.uk/8460/ Developing groundwater for secure water supplies in Africa]. Desalination 248, 546-556. doi: 10.1016/j.desal.2008.05.100

[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Additional resources | Resource pages ]] >> Overview of Groundwater in Africa

[[Category:Additional resources]]
[[Category:Africa Groundwater Atlas]]

Overview of Groundwater in Africa

2023-11-28T14:26:17Z

KirstyUpton:

[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Additional resources | Resource pages ]] >> Overview of groundwater resources and hydrogeological environments in Africa

Please cite page as: Africa Groundwater Atlas. 2019. Overview of Groundwater in Africa. British Geological Survey. Accessed [date you accessed the information]. ''Weblink''.

TEST
==Groundwater in Africa==

Groundwater has many advantages as a source of safe, sustainable water in Africa. It is particularly suited to regions with large rural populations, where demand for water is dispersed across large areas. The main advantages and limitations of groundwater as a water resource are summarised below.

====Advantages of groundwater as a water resource in Africa====

*Groundwater can be found in most environments, at least enough to provide small domestic supplies. It is therefore usually available close to the point of demand.
*Groundwater usually has excellent natural water quality and is usually suitable for potable use with no prior treatment.
*Groundwater is naturally more protected from contamination than surface water/
*Groundwater provides large volumes of natural water storage. Seasonal variations in amount or quality aren't usually significant, so that groundwater is more drought resistant than surface waters.
*Groundwater lends itself well to principles of community management. It can be developed incrementally, often at relatively low cost/initial capital investment.

====Limitations of groundwater as a water resource in Africa====

*In some hydrogeological environments, considerable investment is needed to locate and develop suitable sites for groundwater abstraction - dug wells, drilled boreholes or improved springs.
*In some hydrogeological environments, there can be natural groundwater quality problems - such as iron, fluoride or arsenic.
*As human development increases, the threat of groundwater pollution increases, and there is a greater need for awareness of, and action on, groundwater and aquifer protection.
*Groundwater can be vulnerable to over-abstraction, particularly in low productivity aquifers and/or as water demand and the ability to abstract large volumes of water both grow. Long term changes in rainfall patterns can also impact on groundwater recharge and renewal.
*As overall water supply coverage increases, more hydrogeologically difficult areas can remain unserved, and they become more costly to develop.

===Hydrogeological environments in Africa===

Groundwater is found in [https://en.wikipedia.org/wiki/Aquifer '''aquifers'''] - underground layers of water-bearing rock or sediment that contain groundwater. Aquifers are very different in different places, depending on the type and history of rock or sediment of which they are made - ie, depending on their [https://en.wikipedia.org/wiki/Geology '''geology'''] and their weathering history.

How and where groundwater occurs depends primarily on '''geology''' (including weathering) and on '''rainfall''' (both current and historic). The interaction between these factors gives rise to complex '''hydrogeological environments''', with countless variations in the quantity, quality, ease of access to and renewability of groundwater resources. Because the [https://en.wikipedia.org/wiki/Hydrogeology hydrogeology] - of different hydrogeological environments - in other words, how groundwater exists and behaves - is very different, it is often necessary to use different methods to find, abstract and manage groundwater in different environments. A good understanding of the hydrogeological environment is essential in order to successfully develop groundwater resources.

Africa is hugely diverse in its geology, climate and hydrology. As a result, the hydrogeology of Africa is also hugely variable. But at a continental scale, there are only four main types of '''hydrogeological environment''' (or '''aquifer type''') - shown in the map, below:

*'''basement''' aquifers;
*'''volcanic''' aquifers;
*'''consolidated sedimentary''' aquifers (which can be dominated by either fracture and/or intergranular flow); and
*'''unconsolidated sedimentary''' aquifers.

A detailed description of these environments is in [https://nora.nerc.ac.uk/501047/ MacDonald and Davies (2001)]; and a summary is below.

[[File:Africa_Hgcl_Envs.png|thumb| 400px|center| The main hydrogeological environments in Africa]]

====Basement aquifers====

Crystalline basement rocks of Precambrian age underlie much of Africa. They form low productivity aquifers that provide small rural water supplies for tens, if not hundreds, of millions of people. Groundwater occurs where the rocks have been significantly weathered and/or in fracture zones, most of which are usually shallower than a few tens of metres depth. Borehole and well yields are generally low, but usually sufficient for rural demand.

<center>

<div><ul>

<li style="display: inline-block;"> [[File:weathered basement.png| 300 px| thumb |left | Groundwater occurrence in a weathered basement aquifer]] </li>

</ul></div>

</center>

====Volcanic aquifers====

Volcanic rocks underlie a small but significant proportion of Africa's land area, and are an important water source for tens of millions of people, many of whom live in the drought stricken areas of the Horn of Africa. Groundwater in volcanic aquifers is found within palaeosoils and fractures between lava flows. Yields can be high, and springs are important sources in highland areas.

<center>

<div><ul>

<li style="display: inline-block;"> [[File:volcanic_aquifers.png| 300 px| thumb| right| Groundwater occurrence in a volcanic rock aquifer]] </li>

</ul></div>

</center>

====Consolidated sedimentary aquifers====

Consolidated sedimentary rocks underlie around one third of Africa's land area, and can form thick, highly productive aquifers. The most significant aquifers are sandstones and limestones, which can be exploited for large urban as well as rural supplies. Mudstones however, which account for about 65% of all sedimentary rocks in Africa, contain little groundwater, and careful study is required to develop groundwater supplies from mudstones.

<center>

<div><ul>

<li style="display: inline-block;"> [[File:sedimentary_aquifers.png| 300 px| thumb| left | Groundwater occurrence in a consolidated sedimentary aquifer]] </li>

</ul></div>

</center>

====Unconsolidated sedimentary aquifers====

Unconsolidated sediments directly underlie much of Africa, and are extremely important for both rural and urban water supplies. Unconsolidated sands and gravels occur in most river valleys throughout Africa, and in many coastal areas. These deposits are often highly permeable and can store large volumes of groundwater at shallow depths, which is easy to exploit by traditional shallow wells and boreholes.

<center>

<div><ul>

<li style="display: inline-block;"> [[File:riverside_alluvium.png| 300 px| thumb| right| Groundwater occurence in unconsolidated valley alluvium]] </li>

</ul></div>

</center>

===More Information===

More information on geology and aquifer characteristics across Africa can be found in these [[Additional resources | resource pages]]: [[Geology | geology]]; [[Hydrogeology Map | hydrogeology map]]; and [[Aquifer properties| aquifer properties]]. More detailed information on aquifers in each country can be found in the [[Hydrogeology by country | country pages]].

Maps summarising the hydrogeology of Africa:
[https://www2.bgs.ac.uk/groundwater/international/africanGroundwater/maps.html Quantitative Groundwater Maps for Africa]

MacDonald, A.M. & Davies, J. 2000. [https://nora.nerc.ac.uk/501047/ A brief review of groundwater for rural water supply in sub-Saharan Africa]. British Geological Survey Report WC/00/033.

MacDonald, A.M., Bonsor, H.C., Ó Dochartaigh, B.É. & Taylor, R.G. 2012. [https://iopscience.iop.org/article/10.1088/1748-9326/7/2/024009;jsessionid=18D8D7F69C3ACBEED0D7494F46850BD6.c1 Quantitative maps of groundwater resources in Africa]. Environmental Research Letters 7(2).

MacDonald, A.M. & Calow, R.C. 2009. [https://nora.nerc.ac.uk/8460/ Developing groundwater for secure water supplies in Africa]. Desalination 248, 546-556. doi: 10.1016/j.desal.2008.05.100

[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Additional resources | Resource pages ]] >> Overview of Groundwater in Africa

[[Category:Additional resources]]
[[Category:Africa Groundwater Atlas]]

Overview of Groundwater in Africa

2023-08-17T11:52:48Z

KirstyUpton:

Hydrogeology of Kenya

2022-01-24T09:43:04Z

KirstyUpton: /* Groundwater quantity */

[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Kenya

[[File:CC-BY-SA_logo_88x31.png | frame | This work is licensed under a [https://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License]]]

Kenya has a long history of farming and trade, with the coastal zone home to many Swahili city-states that were trading with the Arab world at least 2000 years ago. In the 17th century the Swahili coast came under Arab rule, and a slave trade expanded. In the late 19th century first German then British colonial powers took control. During the British colonial period, plantation agriculture, particularly coffee and tea, was developed in the central Highlands, while indigenous landless farmers were displaced to cities. From 1952 to 1959 Kenya saw widespread conflict during the Mau Mau uprising against British rule. Kenya became independent in 1963. Kenya’s post colonial history has included periods of political, civil and military instability, most recently notably post-election violence in 2007.

Kenya’s economy is East Africa’s largest, and is dominated by the service sector. Much of this is tourism, which relies heavily on Kenya’s diverse ecology. Agriculture is also a major livelihood activity for much of the population, including large and small scale pastoralism, particularly in semi-arid zones, and is a major employer and contributor to export income, particularly tea, coffee and more recently fresh flowers. However, Kenya still has a low Human Development Index.

Kenya relies on both surface water resources, from rivers, lakes and dammed reservoirs; and on groundwater. Dependence on groundwater is highest in rural areas and in the coastal zone, where urban areas also rely on groundwater. Access to improved water supplies in rural areas remains low, and in urban areas actually reduced from 92% in 1990 to 82% in 2015. Kenya has experienced periodic droughts, including a severe drought in 2011 after two failed rainy seasons.

==Authors==

'''Maxwell Barasa''', Rural Focus Ltd, Kenya

'''Brighid Ó Dochartaigh''', '''Emily Crane''', '''Dr Kirsty Upton''', British Geological Survey, UK

'''Dr Imogen Bellwood-Howard''', Institute of Development Studies, UK

Please cite this page as: Barasa, Crane, Upton, Ó Dochartaigh and Bellwood-Howard, 2018.

Bibliographic reference: Barasa M, Crane E, Upton K, Ó Dochartaigh BÉ and Bellwood-Howard I. 2018. Africa Groundwater Atlas: Hydrogeology of Kenya. British Geological Survey. Accessed [date you accessed the information]. http://earthwise.bgs.ac.uk/index.php/Hydrogeology_of_Kenya

==Terms and conditions==

The Africa Groundwater Atlas is hosted by the British Geological Survey (BGS) and includes information from third party sources. Your use of information provided by this website is at your own risk. If reproducing diagrams that include third party information, please cite both the Africa Groundwater Atlas and the third party sources. Please see the [[Africa Groundwater Atlas Terms of Use | Terms of use]] for more information.

==Geographical Setting==

===General===

Kenya ranges in elevation from sea level to over 5500 m, and can be divided into a number of physiographic units, including the the coastal belt and plains; plateaux; plains; highlands (western and eastern); and the Kenya Rift Valley.

[[File:Kenya_Political.png | right | frame | Kenya. Map developed from USGS GTOPOPO30; GADM global administrative areas; and UN Revision of World Urbanization Prospects. For more information on the map development and datasets see the [[Geography | geography resource page]].]]

{| class = "wikitable"
|-
|Capital city || Nairobi
|-
|Region || Eastern Africa
|-
|Border countries ||
Somalia, Ethiopia, South Sudan, Uganda, Tanzania
|-
|Total surface area* || 580,370 km<sup>2</sup> (58,037,000 ha)
|-
|Total population (2015)* || 46,050,000
|-
|Rural population (2015)* ||34,072,000 (74%)
|-
|Urban population (2015)* || 11,978,000 (26%)
|-
|UN Human Development Index (HDI) [highest = 1] (2014)*|| 0.5484
|}

<nowiki>*</nowiki> Source: [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en FAO Aquastat]

===Climate===

Kenya's climate varies from almost equatorial to high alpine.

[[File:Kenya_ClimateZones.png | 375x365px |Koppen Geiger Climate Zones]][[File:Kenya_ClimatePrecip.png | 375x365px |Average Annual Precipitation]][[File:Kenya_ClimateTemp.png | 375x365px |Average Temperature]]

[[File:Kenya_pre_Monthly.png| 255x124px| Average monthly precipitation for Kenya showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File:Kenya_tmp_Monthly.png| 255x124px| Average monthly temperature for Kenya showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File:Kenya_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File:Kenya_pre_Mts.png|255x124px | Monthly precipitation (blue) over the period 2000-2012 compared with the long term monthly average (red)]]

More information on average rainfall and temperature for each of the climate zones in Kenya can be seen at the [[Climate of Kenya | Kenya climate page]].

These maps and graphs were developed from the CRU TS 3.21 dataset produced by the Climatic Research Unit at the University of East Anglia, UK. For more information see the [[Climate | climate resource page]].

===Surface water===

{|

|-

|Kenya's main rivers originate in the central highlands or in the southern foothills of the Ethiopian highlands. The Rift Valley is a dominant control on surface water flows. West of the Rift Valley, surface water flows towards Lake Victoria and into the Nile Basin; east of the Rift Valley, surface water flows southeast to the Indian Ocean. For the water resource management purposes, five main catchments are identified: Lake Victoria basin, Rift Valley basin, Athi river basin, Tana river basin and Ewaso Ngiro river basin (Pavelic et al. 2012). These large basins are in turn subdivided into 52 main basins and sub-basins (United Nations 1989).

| [[File:Kenya_Hydrology.png | frame | Major surface water features of Kenya. Map developed from World Wildlife Fund HydroSHEDS; Digital Chart of the World drainage; and FAO Inland Water Bodies. For more information on the map development and datasets see the [[Surface water | surface water resource page]].]]

|}

===Soil===

{|

|The major soil types in Kenya are solonetz, luvisols and cambisols.

| [[File:Kenya_soil.png | frame | Soil Map of Kenya, from the European Commission Joint Research Centre: European Soil Portal. For more information on the map see the [[Soil | soil resource page]].]]

|
|}

===Land cover===

{|

|-

|There are a number of distinct ecological zones in Kenya, including Alpine grasslands at high altitudes; humid to dry sub-humid zones; semiarid zones; and arid zones.

| [[File:Kenya_LandCover.png | frame | Land Cover Map of Kenya, from the European Space Agency GlobCover 2.3, 2009. For more information on the map see the [[Land cover | land cover resource page]].]]

|}

===Water statistics===

{| class = "wikitable"
| || 2003 ||2010||2012||2014||2015
|-
|Rural population with access to safe drinking water (%) || || || || || 56.8
|-
|Urban population with access to safe drinking water (%) || || || || || 81.6
|-
|Population affected by water related disease ||No data ||No data ||No data ||No data || No data
|-
|Total internal renewable water resources (cubic metres/inhabitant/year) || || || ||449.5 ||
|-
|Total exploitable water resources (Million cubic metres/year) || No data || No data || No data || No data || No data
|-
|Freshwater withdrawal as % of total renewable water resources || ||10.48 || || ||
|-
|Total renewable groundwater (Million cubic metres/year) || || || ||3,500 ||
|-
|Exploitable: Regular renewable groundwater (Million cubic metres/year)|| || || 600|| ||
|-
|Groundwater produced internally (Million cubic metres/year) || || || || 3,500||
|-
|Fresh groundwater withdrawal (primary and secondary) (Million cubic metres/year) || No data || No data || No data || No data ||
|-
|Groundwater: entering the country (total) (Million cubic metres/year) || || || || ||
|-
|Groundwater: leaving the country to other countries (total) (Million cubic metres/year) || || || || ||
|-
|Industrial water withdrawal (all water sources) (Million cubic metres/year) || |125| || || ||
|-
| Municipal water withdrawal (all water sources) (Million cubic metres/year) || ||1,186 || || ||
|-
|Agricultural water withdrawal (all water sources) (Million cubic metres/year) || ||1,907 || || ||
|-
|Irrigation water withdrawal (all water sources)* (Million cubic metres/year) || ||1,602 || || ||
|-
|Irrigation water requirement (all water sources)* (Million cubic metres/year) ||486 || || || ||
|-
|Area of permanent crops (ha) || || || ||530,000||
|-
|Cultivated land (arable and permanent crops) (ha) || || || || 6,330,000||
|-
|Total area of country cultivated (%) || || || || 10.91||
|-
|Area equipped for irrigation by groundwater (ha) || ||19.87 || || || ||
|-
|Area equipped for irrigation by mixed surface water and groundwater (ha) ||No data || No data || No data || No data || No data
|}

These statistics are sourced from [http://www.fao.org/nr/water/aquastat/main/index.stm FAO Aquastat]. More information on the derivation and interpretation of these statistics can be seen on the FAO Aquastat website.
Further water and related statistics can be accessed at the [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en Aquastat Main Database].
1 More information on [http://www.fao.org/nr/water/aquastat/water_use_agr/index.stm irrigation water use and requirement statistics]

==Geology==

This section provides a summary of the geology of Kenya. More detail can be found in the references listed at the bottom of this page. Many of these references can be accessed through the [http://www2.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].

The geology map on this page shows a simplified version of the geology at a national scale (see [[Geology | the Geology resource page]] for more details).

[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Kenya geology and hydrogeology map'''].

[[File:Kenya_Geology3.png | center | thumb| 500px | Geology of Kenya at 1:5 million scale. Developed from USGS map (Persits et al. 2002). For more information on the map development and datasets see the [[Geology | geology resource page]]. [https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html Download a GIS shapefile of the Kenya geology and hydrogeology map].]]

{| class = "wikitable"

|+ Geological Environments

|Key Formations||Period||Lithology||Structure

|-

!colspan="4"|Sedimentary - largely unconsolidated

|-
|Baratamu Formation (Miocene-Eocene); Marafa Formation and Magarini Sands (Pliocene); Kilindini Formation (Pleistocene); and Recent deposits
||Tertiary-Quaternary
||Sedimentary deposits are common in various parts of Kenya, usually occuring at the base of, or intercalating with, volcanic successions, or deposited in tectonic troughs. The repeated faulting of the Rift Valley floor and the numerous volcanic eruptions created many short-lived basins with internal drainage in which lacustrine and fluviatile sediments accumulated. Sediment types include soils; alluvial and coastal beach sands and dune sands, evaporates, fossil coral reef and lagoonal formations and coastal sandstones; and alluvial and lacustrine sediments in the Rift Valley.

Most of these sediments are unfossiliferous, but a few are of interest as they contain deposits that bear artefacts and interesting fossils that have been studied extensively. The more important sediments of middle Pleistocene are the Olorgesaillie lakebeds, a lacustrine series with much diatomite, mammalian fossils and artefacts. This is also comparable to the Kariandusi sediments near Gilgil and the Kanjera Beds in the Kavirondo Gulf off Lake Victoria. Olorgesaillie beds and Kariandusi sediments occur in the Rift Valley. Some early Tertiary formations do not crop out at the ground surface.
||

|-

!colspan="4"| Igneous Volcanic

|-

|

||Tertiary-Quaternary

||Volcanic rocks cover the central parts of the country from south to north, occurring in the floor of the Rift Valley and on the peneplains west and east of the valley.

The oldest are of Lower Miocene age and comprise the eroded lavas and pyroclastic piles of South Nyanza. Late in Miocene times, Kapiti and Yatta phonolites were erupted and flowed to great lengths. Further eruptions accompanied by faulting persisted and also gave rise to the Rift Valley and the volcanic piles of Mounts Kenya, Elgon and Kilimanjaro.

Quaternary volcanism was mostly within the Rift Valley and has given rise to the craters and cinder cones that are found in the floor of the valley, e.g. Longonot, Menengai and Suswa.

||

|-

!colspan="4"| Sedimentary – Mesozoic-Palaeozoic
|-

|Mtombku Formation (Jurassic-Cretaceous); Kambe Limestone & Mazeras Formation (Jurassic); Mariakani Sandstone (Triassic); Maji-ya-Chumvi (Permian-Triassic) and Taru Grits (Permian)

||Mesozoic-Palaeozoic

||Palaeozoic and Mesozoic formations in Kenya are found near the coast and in the northeast.

The oldest of these rocks include the Taru, Maji-ya-Chumvi, Mariakani and Mazeras formations, which are dominantly sandstones, shales and siltstones, and form the Duruma series - equivalent to the Karroo system in southern Africa. They extend for about 100 km from Taru to Mazeras, west of Mombasa.

Younger rocks occur in two separate areas, in the northeast of Kenya and along the coastal belt. The sratigraphy and fossils in the two areas are very distinct and it is likely that the sedimentary basins in the two areas were connected. Revision mapping in the area has come up with interesting lithological units that have revised lithological names. They include limestones as well as sandstones, siltstones and shales, including the Kambe Limestone and Mtombku Formation.

||The rocks of the Duruma series between Taru and Mazeras dip very gently towards the ocean and are heavily faulted in places.

|-

!colspan="4"| Precambrian

|-

|Bukoban system and Mozambique Belt

||Proterozoic

||The Kisii series of the Bukoban system comprises metamorphosed volcanic rocks with metasedimentary rocks.

The Mozambique belt is a structural unit within which a wide variety of metasedimentary and meta-igneous rocks are found, with a broad concordance of structural style and metamorphic history. The degree of deformation is intense in most of the rocks, and they are of high metamorphic grade. They were referred to in earlier literature as basement system rocks, due to the high degree of metamorphism and deformation. Recent work on the Mozambique Belt has shown that rocks can be sub-divided into groups of contrasting lithology, structure and composition of igneous rocks content. Rock types include quartzites, biotite/hornblende gneisses, schist, granitoid gneisses, amphibolites and migmatites, and there are intrusions of syntectonic granites. These groups are being studied in greater detail in order to come up with proper chronostratigraphic terminology. Within the Mozambique Belt, basic igneous complexes range in size from bosses to small dykes. They occur both east and west of the Rift Valley. Some of the older basic intrusions have undergone deformation and metamorphism to give orthoamphibolites and charnockitic gneisses. Basic and granitic intrusions are known in the Mozambique Belt. The majority of Mozambique rocks have been placed in upper Precambrian (Proterozoic).

||The most characteristic feature of the Mozambique Belt is its structural trend, which is more or less north-south across the entire belt. Variations of the northerly trend are minor and when observed can be explained and are localised.

|-

|Kavirondian and Nyanzian

||Archaean

||The Nyanzian and Kavirondian systems forming the Nyanza Craton are the oldest rocks in the country, with ages over 2,500 million years.

The Nyanzian system is mainly composed of lavas and pyroclastics with minor sediments (including shales and cherts) and banded ironstones.

The Kavirondian, which rests uncomfortably on the Nyanzian, consists of grits, sandstones, mudstones, greywackes and conglomerates.

Numerous granitic bosses and batholiths have intruded the Nyanzian and Kavirondian. There are more Kavirondian intrusions, but pre-Kavirondian intrusions are also widespread, and the two systems are discernible.

||Both the Nyanzian and Kavirondian systems are isoclinally folded about axes that have an east-westerly trend. Kavirondian, is only slightly younger than Nyanzian but folding in the two systems has similar orientation.

|-

|}

==Hydrogeology==

This section provides a summary of the hydrogeology of the main aquifers in Kenya. More information is available in the references listed at the bottom of this page. Many of these references can be accessed through the [http://www2.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].

The hydrogeology map on this page shows a simplified version of the type and productivity of the main aquifers at a national scale (see the [[Africa Groundwater Atlas Hydrogeology Maps | Hydrogeology Map]] resource page for more details).

[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Kenya geology and hydrogeology map'''].

[[File: Kenya_Hydrogeology3.png | center | thumb | 500px | Map of hydrogeology (aquifer type and productivity) of Kenya at 1:5 million scale. For more information on how the map was developed see the [[Africa Groundwater Atlas Hydrogeology Maps | Hydrogeology map]] resource page. [https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html Download a GIS shapefile of the Kenya geology and hydrogeology map].]].

The Water Resources Management Authority (WRMA) classifies Kenya's aquifers as follows:

{| class = "wikitable"

|Class||Description||Examples||

|-

|Strategic aquifer

||Aquifer used to supply significant amounts/ proportions of water in a given area and for which there are no available alternative resources, or where such resources would take time and money to develop; significant transboundary aquifers

||Tiwi, Nairobi, central Merti, Sabaki, Nakuru, Kabatini, Lake Naivasha Lamu Island

|-

|Major aquifer

||High-yield aquifer systems with good quality water

||Daua and Elgon volcanic rock aquifers
|-
|Minor aquifer

||Moderate-yield aquifer systems with variable water quality.

||Mandera - Jurassic (Mesozoic-Palaeozoic)
|-
|Poor aquifer

||Low- to negligible-yield aquifer systems with moderate to poor water quality.

||Basement System
|-
|Special aquifer
||Aquifer systems designated as such by WRMA
||Isinya
|-
|}

The following summary classifies Kenya's aquifers differently, by their geological environment, which controls the way in which groundwater occurs and behaves in the different aquifers. Some of the strategic and major aquifers listed above are described in more detail, and information is provided on some of the poorer aquifers which nevertheless may form a local resource.

====Sedimentary - Unconsolidated and Semiconsolidated; Intergranular Flow: Moderate to High Productivity Aquifer====

{| class = "wikitable"

|Named Aquifers||General Description||Water quantity issues||Water quality issues||Recharge
|-

|Lotikipi and Lodwar aquifers

||Alluvial sands and sediments, which range up to 80 m deep. They can have high groundwater potential where dominated by coarse grained sediments (sand and gravel), but elsewhere, groundwater potential is typically limited.
||
||Groundwater in the Lotikipi aquifer is very saline, with conductivity values exceeding 8000 uS/cm.
||Recharge occurs both by direct rainfall infiltration and, to the Lodwar aquifer, by leakage from the River Turkwel.
|-
|Tiwi aquifer
||Small outcrop but strategically important in the Kwale area. It is also termed the Kilindili Sands. The lithology is alluvial and lacustrine sand and clay and is typically not more than 70 m deep. The aquifer is semi-confined or confined, with water levels 25 to 30 mbgl. High borehole yields can be obtained, and boreholes are typically 40 – 80 m deep. Transmissivity values range from 120 to 600 m²/d, and storage coefficients from 9.3 x 10-³ to 8.0 x 10-².
||
||Typically good quality. Vulnerable to saline intrusion.
||Recharged from groundwater flow from the west and possibly also by leakage from seasonal swamps and lakes directly overlying the aquifer.
|-

|Gongoni/Msambweni Aquifer
||The Gongoni/Msambweni Aquifer occurs in the Kwale area. High yields can be obtained. Boreholes are typically 40 – 100 m deep.
||
||Generally good quality, apart from high iron concentrations.
||Recharge occurs by direct rainfall infiltration and also by leakage from the River Mkurumudzi.
|-
|Baricho Aquifer
||The Baricho aquifer is small but strategic in the coastal zone and comprises approximately 20 m of alluvial sand and gravel overlying around 40 m of Jurassic Mazeras Sandstone and Kambe Limestone. Good borehole yields can be obtained, and boreholes are typically drilled to 25 – 60 m depth. The aquifer is semi-confined to unconfined, with vertical hydraulic conductivities between 75 and 500 m/d, inferring transmissivities of 3,750 to 25,000 m2/d for a saturated thickness of 50 m; specific yield ranges from 0.15 to 0.285 (Mumma et al. 2011).
||
||Generally good quality, sometimes elevated total dissolved solids (TDS). SEC ranges from 390 to 680 μS/cm.
||Recharge occurs dominantly by leakage from the River Galena.
|-

|Merti Aquifer

||The Merti Aquifer occurs in Wajir County and comprises semi-consolidated clays, sands, sandstones and limestones . Groundwater is usually confined and water levels lie at 90 to 120 m below ground level.
found at fairly uniform depths of between 110 and 180 m below ground level. The aquifer is thought to be between 80 and 280 m thick. Successful boreholes are commonly between 105 m to 150 m bgl (GIBB Africa Ltd 2004). Transmissivity ranges from 0.2 to 840 m²/d depending on the facies, with higher transmissivities in coarse grained materials. The median transmissivity is 275 m²/d (n = 20). Storage coefficients range from 4.3 x 10-5 to 6.7 x 10-4 (n = 6). The hydraulic gradient ranges from 0.001 in the western part of the aquifer, falling to 0.0001 to 0.005 toward the border with Somalia (Mumma et al. 2011).
||Locally subject to over-exploitation (Mumma et al. 2011)
||Highly variable. Freshest in the centre of the aquifer, becoming more mineralised to north and south (Mumma et al. 2011). Saline water has been observed in the Merti aquifer and is also believed to underlie the fresh water layer. Water quality in the Dadaab refugee camps has deteriorated over time, mainly due to increasing salinity. In Habaswein there is evidence of some salinisation as a result of long term abstraction (Mumma et al. 2011, Oord et al. 2014).
||Modern recharge is limited; most abstraction is of fossil water (Mumma et al. 2011).

|}

Key references for these aquifers are Acacia Water, GIBB Africa Ltd (2004), '''Mumma et al. (2011)''' and Oord et al. (2014) (see Reference section, below).

====Igneous Volcanic: Moderate Productivity Aquifer====

{| class = "wikitable"

|Named Aquifers||General Description||Water quantity issues||Water quality issues

|-

|General volcanic aquifers

||The volcanic rocks in Kenya vary from a few metres to several hundred metres thick. Groundwater flow and storage occur in fractures and weathered zones, often along the sub-horizontal boundaries between successive lava flows, which at one time were land surfaces. Boreholes in the volcanic aquifers are up to 125 m depth, and may encounter more than five discrete aquifer layers. These aquifer layers are often confined. Yields, depth to aquifers and rest water levels vary significantly. A specific capacity value of 0.2 m³/hour/m is quoted (Pavelic et al. 2012, Ministry of Water Development 1992). An average yield of 7.5 to 7.6 m³/hour is quoted for boreholes in volcanic rocks (Pavelic et al. 2012, United Nations 1989), with a large drawdown of 37 m (Pavelic et al. 2012). A hydraulic conductivity value of 0.0144 m/d is quoted.
||
||Groundwater typically has low total dissolved solids and high bicarbonate. The volcanic deposits of the East African Rift System are rich in fluoride which leads to high groundwater fluoride concentrations. For example, concentrations over 10 mg/L were found in the Nairobi area (Coetsiers et al. 2008).
|-

|Nairobi Aquifer

||The Nairobi aquifer is one of the most significant in Kenya. It comprises Plio-Pleistocene volcanics interbedded with old land surface and intervolcanic sediments, and underlies much of the Nairobi metropolitan area. It is a complex multilayered aquifer system, recharged along the eastern edge of the Rift Valley with groundwater moving toward the east. It is unconfined in the recharge zone, becoming confined towards the east. The main aquifer layer, the Upper Athi Series, is confined and typically found at depths of 120 to 300 m bgl. Transmissivity values range from 0.1 to 160 m²/d, with hydraulic conductivities ranging from 0.01 to 1.3 m/d. Storage coefficient values range from 1.2 x 10<sup>-4</sup> to 4.2 x 10<sup>-1</sup> (Mumma et al. 2011). Boreholes are typically drilled to 250 to 400 m depth.
||Overabstraction causing lowered water levels.
||Often shows naturally high fluoride.
||Recharge by rainfall infiltration on the Ngong Hills along the eastern edge of the Rift Valley.
|-

|Kabatini aquifer
||The Kabatini aquifer occurs within the volcanic rocks of the Nakuru area. Boreholes are typically drilled to about 150 m depth.
||
||Elevated fluoride concentrations.
||

|}

A key reference for these aquifers is Coetsiers et al. (2008).

====Sedimentary: Mixed Intergranular & Fracture Flow: Moderate Productivity Aquifer====

{| class = "wikitable"

|Named Aquifers||General Description

|-
|
||Little information on these aquifers is known.
|}

====Basement: Low to Moderate Productivity Aquifer====

{| class = "wikitable"

|Named Aquifers||General Description||Water quantity issues||Water quality issues||Recharge

|-
|
||An average yield of 4.4 m³/hour is quoted for boreholes in Precambrian basement aquifers (United Nations 1989).
||
||
||

|}

==Groundwater Status==

Some aquifers are identified as being impacted by overabstraction and/or water quality deterioration. [http://www.wrma.or.ke/index.php/about-us/departments-79/technical-coordination/ground-water/aquifer-maps-&-classification.html WRMA] is preparing a large scale map of groundwater stressed areas.

===Groundwater quantity===

The total potential groundwater resource (storage) in Kenya is estimated to be 619 million m³ (Pavelic et al. 2012). The total groundwater abstraction rate in in 2012 was estimated at 57.21 million m³/year, and the total safe abstraction rate (annually recharged) in Kenya is estimated to be 193 million m³/year (Ministry of Water Development 1992, Pavelic et al. 2012).

Some aquifers are identified as being overabstracted with associated problems of water level decline and sometimes water quality deterioration, in particular the Nairobi volcanic aquifer.

===Groundwater quality===

Some aquifers, mostly with recharge from fresh water rivers, are excellent groundwater sources e.g. the Lodwar Aquifer recharged by the River Turkwel; the Merti Aquifer recharged by the River Ewaso; the Gongoni Aquifer recharged by the Mkurumudzi River and the Baricho Aquifer recharged by the River Galena.

Many aquifers have groundwater quality issues. For example, the Nairobi aquifer has high fluoride concentrations, which mostly exceed WHO standards, especially towards the Embakasi area.

The Lotikipi Aquifer is very saline with conductivity exceeding 8000 µS/cm.

The Mombasa Island Pleistocene sands and limestones and related aquifers are impacted by pollution and saline intrusion. The Mumias granites are impacted by pollution and salinisation.

===Surface water-groundwater interaction===

Various contamination problems arise due to the hydraulic continuity between surface water and shallow groundwater systems in Kenya, e.g.:

*Poor sewerage and drainage systems are major contributors to groundwater contamination. This is an increasing problem in Nairobi and its environs.

*Open cast mining of stones pose a threat to groundwater as a result of contaminated water infiltrating into the ground.

*The Kiserian reservoir has suffered contamination problems due to inadequate sewage systems in nearby towns; this contaminated water may find its way into groundwater. Equally, groundwater may be becoming directly contaminated as a result of reliance on pit latrines and soakaway pits.

*River pollution by industrial wastes and sewage pose a great risk for groundwater protection.

==Groundwater use and management==

=== Groundwater use===

Many parts of Kenya rely on groundwater, either directly from privately owned or communal boreholes, or via piped supplies from groundwater wellfields. Groundwater from communal boreholes or hand dug wells supplies most of the rural population. Groundwater is used locally for mining, e.g. the Gongoni well field used for the Base Titanium mining company. The Daadab refugee camp depends on groundwater abstracted from the Merti aquifer. Most irrigation in Kenya is supplied by surface water, but groundwater supplies a small proportion of irrigation water.

It is reported that although groundwater exploitation has considerable potential for boosting water supplies in Kenya, its use is limited by poor water quality, overexploitation, saline intrusion along the coastal areas, and inadequate knowledge of the occurrence of the resource (Mumma et al. 2011). Nevertheless, many areas of Kenya are reliant on groundwater sources for domestic, commercial and industrial needs, including the coastal zone which is almost entirely dependent on groundwater. Other areas include Mombasa and Malindi (which depend on the Baricho wellfield); Kwale (dependent on the Tiwi wellfield); and Wajir (dependent on the Merti aquifer); as well as Naivasha, Nakuru, Mandera, and Lodwar (Mumma et al. 2011).

=== Groundwater management===

====Legislation and regulation====

Water resources legislation in Kenya has gone through many changes in recent decades. After independence in 1964, the government defined water as a national good and began developing rural water supply schemes through local government councils, with support from international donors. Ambitious development of water schemes during the 1970s slowed at the start of the 1980s due to government budget constraints, and Kenya saw successive periods of centralisation and decentralisation of water supply management, with mixed success. Major changes in the water sector were seen following the Water Act of 2002, and in 2010 Kenya’s new constitution enshrined water and sanitation as a human right.

The most recent water legislation was the 2016 Water Act, which recognises groundwater as a key resource and emphasises the need for groundwater protection. The 2030 Water Resources Group produced a useful note describing the [https://www.2030wrg.org/wp-content/uploads/2016/12/Understanding-the-Kenyan-Water-Act-2016.pdf essentials of the Water Act 2016]. The Act created the [https://www.wra.go.ke/ Water Resources Authority] (WRA) from the former Water Resources Management Authority (WRMA). The objective of the WRA is to regulate the management and use of water resources. The WRA is responsible for:

* Water regulation: to sustainably and equitably allocate water resources among competing needs, such as planning and issuing water abstraction permits, including permits for new water boreholes, and setting and collecting permit and water user fees.
* Water resource protection: to control pollution and improving water quality in Kenya's water bodies, including integrating land use activities and human activities into WRA Water Quality control programs.
* Information collection and dissemination: collecting, analysing, storing and dissemination information on water resources. This includes a requirement for borehole logs and test pumping data for all new water boreholes to be collected by borehole drillers/developers and returned to the WRA.
* Climate change adaptation: WRA has specific responsibilities relating to the control of water resources in disasters that have been brought about by climate change effects.

Prior to the Water Act 2016, the Water Act of 2002 created the mechanisms for planning, including the establishment of the Water Resources Management Authority (WRMA), which had responsibility for regulating the ownership and control of water and making provision for the conservation of surface and groundwater and the supply of services in relation to water and sewerage (Mumma et al. 2011). In 2006, WRMA proposed a policy for the protection of groundwater (Mumma et al. 2011).

The [http://www.water.go.ke/ Ministry of Water & Sanitation and Irrigation] (formerly Ministry of Water and Irrigation; also known as Ministry of Water and Sanitation) is responsible for the development of water resource legislation, policy formulation, sector coordination and guidance, and monitoring and evaluation.

=== Groundwater monitoring===

WRMA instituted a monitoring program that targets most of the important Kenyan aquifers. The principal disadvantage of the monitoring network currently in place is that the majority of boreholes used are production boreholes and require water levels to return to static levels prior to the measurements. Mumma et al. reported in 2011 that eleven dedicated monitoring boreholes were being constructed in a variety of aquifers across Kenya, to be equipped with digital loggers.

Across the whole network, WRA attempts to manually collect water level and quality trends quarterly, and for the more intensively used aquifers, water levels are monitored monthly. Water levels have been collected weekly to monthly in the Dadaab Merti by CARE Kenya since 1992, and constitute the longest continuous groundwater level data set in the country (Mumma et al. 2011).

Water quality data are collected for a selection of groundwater sources. For the coastal aquifers, this
includes pH, color, EC25, TDS, chloride, salinity, total alkalinity, total hardness, magnesium, and
calcium (Mumma et al. 2011).

=== Transboundary aquifers===

Kenya shares several transboundary aquifers with neighbouring countries, defined by IWMI (2014) as:

*AFS31 Coastal sedimentary basin 1 (Kenya/Tanzania) - Quaternary and consolidated sedimentary rocks

*AFS32 Kilimanjero aquifer (Kenya/Tanzania) - Volcanic alluvium

*AFNE1 Rift aquifer (Kenya/Tanzania/Uganda) - Volcanic

*AFNE2 Merti aquifer (Kenya/Somalia) - Semi-consolidated sedimentary

*AFNE3 Mount Elgon (Kenya/Uganda) - Volcanic

*AFNE4 Dawa (Ethiopia/Kenya/Somalia) - Volcanic rocks, alluvials and Precambrian basement

*AFNE5 Juba aquifer (Ethiopia/Kenya/Somalia) - Aquifers in Precambrian and intrusive rocks

*AFNE7 Sudd basin (Ethiopia/Kenya/South Sudan/Sudan) - Precambrian and volcanic rocks with patches of alluvials/sedimentary

Source: IWMI (2014).

For further information about transboundary aquifers, please see the [[Transboundary aquifers | Transboundary aquifers resources page]]

==Groundwater Projects==

Information on particular groundwater projects in Kenya, including links to project results and outputs, can be found on the [[Kenya Groundwater Projects | Kenya groundwater projects]] page.

==References ==

The following references provide more information on the hydrogeology and groundwater resources of Kenya.

Many of these, and others, can also be searched through the [https://www2.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=listResults&title_search=&author_search=&category_search=&country_search=KE&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive]

Acacia Water. [http://www.worldagroforestry.org/sites/default/files/TR1%20ARIGA-%20Hydrological%20Assessment%20of%20the%20Merti%20Aquifer%20Kenya.pdf Hydrogeological Assessment of the Merti Aquifer, Kenya]. Technical report no 1 of ARIGA. Assessing Risks of Investment in Groundwater Development in Sub-Saharan Africa.

Adams B. 1986. Tiwi Aquifer Study, Final Report. Prepared on behalf of British Geological Survey for the Ministry of Water Development, Kenya, and British Technical Cooperation

Blandenier L. 2015. [http://doc.rero.ch/record/278340/files/00002503.pdf Recharge quantification and continental freshwater lens dynamics in arid regions: application to the Merti Aquifer (Eastern Kenya)]. PhD Thesis, University of Neuchatel.

Blandenier L. 2016. [https://dspace.lboro.ac.uk/dspace-jspui/bitstream/2134/31303/2/Blandenier-2430.pdf The Merti aquifer (Kenya), a sustainable water resource for the Dadaab refugee camps and local communities?] In: Shaw RJ (ed) Ensuring availability and sustainable management of water and sanitation for all: Proceedings of the 39th WEDC International Conference, Kumasi, Ghana, 11-15 July 2016.

Businge MS, Ondimu K, Maina I, Mutai C, Ochola SO, Ali AA and Mocha A. 2011. [https://na.unep.net/siouxfalls/publications/Kenya_SDM.pdf Kenya: State of the environment and outlook 2010. Supporting the delivery of Vision, 2030]. A publication of the National Environment Management Authority (NEMA ), Kenya

Carruthers RM. 1985. [http://nora.nerc.ac.uk/505659/1/WK_RG_85_4.pdf Report on Geophysical Studies Relating to the Coastal Aquifer of the Mombasa District, Kenya]. Report by the Regional Geophysics Research Group, British Geological Survey, No. RGRG 85/4, Keyworth, Nottingham

Coetsiers M, Kilonzo F and Walraevens K. 2008. Hydrochemistry and source of high fluoride in groundwater of the Nairobi area, Kenya, Hydrological Sciences Journal, 53:6, 1230-1240. doi: 10.1623/ hysj.53.6.1230

Foster T and Hope R. 2016. [http://www.sciencedirect.com/science/article/pii/S0743016716302029?via%3Dihub A multi-decadal and social-ecological systems analysis of community waterpoint payment behaviours in rural Kenya]. Journal of Rural Studies, 47, 85-96.

GIBB Africa Ltd. 2004. UNICEF Kenya Country Office - Study of the Merti Aquifer - Technical Report ISsue 2.0.

Hove ART and Ongweny GSO. 1973. [https://www.jstor.org/stable/43661418 An Outline of Kenya's Groundwater Quality]. Journal of Eastern African Research & Development, Vol. 4, No. 1 (1974), pp67-97. [Weblink accessed 18 October 2021].

IWMI. 2014. [http://www.iwmi.cgiar.org/Publications/Other/PDF/transboundary_aquifer_mapping_and_management_in_africa.pdf Transboundary Aquifer Mapping and Management in Africa].

Katuva JM. 2017. [https://upgro.files.wordpress.com/2015/03/groforgood_poverty_policy_brief_feb2017.pdf Poverty Transitions in Kwale County Policy Brief], February 2017, Gro for GooD project, UPGro/University of Oxford

Koehler J. 2017. [https://upgro.files.wordpress.com/2015/03/groforgood_governance_policy_brief_feb2017.pdf How has devolution fared in its first term? Responses from Kwale County at the end of the transition period]. Policy Brief, February 2017, Gro for GooD project, UPGro/University of Oxford

Koei N. 2013. [http://open_jicareport.jica.go.jp/pdf/12146395_01.pdf The project on the development of the National Water Master Plan 2030]. FINAL REPORT VOLUME - V Sectoral Report (2/3) Japan International Cooperation Agency

KNBS (Kenya National Bureau of Statistics). 2012. [https://www.knbs.or.ke/download/analytical-report-on-amenities-and-household-assets-volume-xi-2/ The 2009 Kenya Population and Housing Census. In: Analytical Report on Housing Conditions, Amenities and Household Assets, Vol. XI]. Kenya National Bureau of Statistics, Nairobi.

Kuria ZN. 2013. [https://www.researchgate.net/publication/289154385_Groundwater_Distribution_and_Aquifer_Characteristics_in_Kenya Groundwater Distribution and Aquifer Characteristics in Kenya]. Developments in Earth Surface Processes 16:83-107, DOI: 10.1016/B978-0-444-59559-1.00008-6 [Weblink accessed 18 October 2021].

Mumma A, Lane M, Kairu E, Tuinhof A and Hirji R. 2011. [https://documents1.worldbank.org/curated/en/955231468337751545/pdf/717260WP0Box370C00GWGovernanceKenya.pdf Kenya: Groundwater Governance Case Study]. Water Papers: Water Partnership Programme. [Weblink accessed 18 October 2021].

Ministry of Water Development. 1992. The Study on the National Water Master Plan. Prepared with the assistance of Japan International Cooperation Agency (JICA).

Olago DO. 2019. [https://link.springer.com/article/10.1007/s10040-018-1895-y Constraints and solutions for groundwater development, supply and governance in urban areas in Kenya]. Hydrogeology Journal, Volume 27, pp1031–1050. [Weblink accessed 18 October 2021].

Oord A, Collenteur R and Tolk L. 2014. [http://www.worldagroforestry.org/sites/default/files/TR1%20ARIGA-%20Hydrological%20Assessment%20of%20the%20Merti%20Aquifer%20Kenya.pdf Hydrogeological Assessment of the Merti Aquifer, Kenya]. Technical report No 1 of ARIGA, Assessing Risks of Investment in Groundwater Development in Sub-Saharan Africa.

Pavelic P, Giordano M, Keraita B, Ramesh V and Rao T. 2012 . [https://www2.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA600020 Groundwater availability and use in Sub-Saharan Africa: a review of 15 countries]. International Water Management Institute.

Republic Of Kenya Parliament. 2014. [http://kenyalaw.org/kl/fileadmin/pdfdownloads/bills/2014/WaterBill2014.pdf National Assembly Bills, The Water Bill (Bill No. 7of 2014)].

Sincat-Atkins/Groundwater Survey (Kenya) Ltd (JVSA/GSK). 1998. Second Mombasa & Coastal Water Supply Engineering and Rehabilitation Project - Tiwi Aquifer Development: Borehole Drilling and Associated Works; Borehole Completion Report. Volume I-III. Report for National Water Conservation & Pipeline Corporation, prepared by Joint Venture Sincat-Atkins in association with Groundwater Survey (K) Ltd. Nairobi, Kenya.

Sosi B, Cheboi E and Simiyu C. 2013. [http://iosrjournals.org/iosr-jagg/papers/vol1-issue6/E0163545.pdf Nonlinear Correlation analysis between Surface Resistivity and Hydraulic Characteristics of the Kabatini Well Field, Upper Lake Nakuru Basin, Kenya Rift]. IOSR Journal of Applied Geology and Geophysics (IOSR-JAGG), Volume 1, Issue 6 (Nov – Dec 2013), 35-45.

Swarzenski WV and Mundorff MJ. 1977. [https://pubs.usgs.gov/wsp/1757n/report.pdf Geohydrology of North Eastern Province, Kenya]. In: Contributions to the hydrology of Africa and the Mediterranean Region, Geological Survey Water-Supply Paper 1757-N. Prepared in cooperation with the Water Department, Kenya Ministry of Agriculture under the auspices of the U.S. Agency for International Development. [Weblink accessed 18 October 2021].

United Nations. 1989. [https://www2.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060011 Groundwater in Eastern, Central and Southern Africa: Kenya]. United Nations Department of Technical Cooperation for Development.

WASREB (Government of Kenya Water Services Regulatory Board). 2014. [https://wasreb.go.ke/downloads/WASREB_Impact_Report8.pdf Impact: a Performance Review of Kenya's Water Services Sector 2012-2013]. Water Services Regulatory Board, Nairobi

2030 Water Resources Group. 2016. [https://www.2030wrg.org/wp-content/uploads/2016/12/Understanding-the-Kenyan-Water-Act-2016.pdf Understanding the Kenyan Water Act 2016].

===Other sources of data and information===

*The [http://www.mining.go.ke/ Ministry of Mining] sells geological maps and geological reports carried out by the Geological Survey of Kenya.

*The [http://www.wrma.or.ke/ Water Resources Management Authority] licences hydrogeological data (borehole logs, aquifer units and yields).

*The [http://nationaloil.co.ke/site/3.php?id=1 National Oil Corporation of Kenya] (NOCK) licences their seismic data, seismic lines and oil well logs.

*The [http://www.samsamwater.com/about.php Samsam Water Foundation] website includes hydrogeological information.

*The [http://geology.uonbi.ac.ke/uon_student_projects University of Nairobi] offers a platform on its website on student research topics which provides useful geological information.

*The [http://data.ilri.org/geoportal/catalog/main/home.page International Livestock Research Institute] (ILRI) has digitized and shapefiles of Kenya Geology, soils and landcover.

* The [https://www.2030wrg.org/ 2030 Water Resources Group] carry out work relating to water resources in Kenya and have produced a number of [https://www.2030wrg.org/kenya-new/reports/ reports on the Kenyan water sector].

Return to the index pages:
[[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Kenya



[[Category:Hydrogeology by country|k]]
[[Category:Africa Groundwater Atlas]]

Hydrogeology of Ethiopia

2020-10-06T15:12:33Z

KirstyUpton: /* Groundwater data */

[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Ethiopia

[[File:CC-BY-SA_logo_88x31.png | frame | This work is licensed under a [https://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License]]]

Ethiopia is one of the oldest countries in the world, having existed within similar borders to today for over 2000 years. For most of its long history its governmental system was an independent monarchy, which was overthrown in 1974. The communist military Derg government that followed was itself overthrown in 1991, since when a shaky democracy has seen several contested elections. The African Union is headquartered in Addis Ababa, Ethiopia’s capital.

Ethiopia’s economy grew rapidly between 2005 and 2010. Agriculture is a major contributor to export income and most of the population is engaged in agriculture. Most agricultural production is by small-scale farmers, but the cash-crop sector accounts for a large proportion of agricultural exports, with the most important being coffee: Ethiopia is the largest coffee exporter globally. The country also has large mineral resources, with gold a major export commodity, but they have not seen much development to date; nor has the investigation of oil potential.

Groundwater provides more than 90% of the water used for domestic and industrial supply in Ethiopia, but a very small proportion of water used for irrigation, which mostly comes from surface water. Ethiopia has vast surface water resources in lakes and rivers, which supply most of the country’s electricity through hydropower. Further expansion of hydropower capacity is planned, including the ‘Grand Ethiopian Renaissance Dam’, which is intended to become the largest hydroelectric power plant in Africa. However, the country has also suffered recurring devastating droughts, with severe impacts including famine, increased poverty and civil unrest.

==Authors==

'''Dr Seifu Kebede''', Addis Ababa University, Ethiopia

'''Addis Hailu''', University of Gondor, Ethiopia

'''Emily Crane''' & '''Brighid Ó Dochartaigh''', British Geological Survey, UK

'''Dr Imogen Bellwood-Howard''', Institute of Development Studies, UK

Please cite this page as: Kebede, Hailu, Crane, Ó Dochartaigh and Bellwood-Howard, 2018.

Bibliographic reference: Kebede, S., Hailu, A., Crane, E., Ó Dochartaigh, B.É and Bellwood-Howard, I. 2018. Africa Groundwater Atlas: Hydrogeology of Ethiopia. British Geological Survey. Accessed [date you accessed the information]. http://earthwise.bgs.ac.uk/index.php/Hydrogeology_of_Ethiopia

==Terms and conditions==

The Africa Groundwater Atlas is hosted by the British Geological Survey (BGS) and includes information from third party sources. Your use of information provided by this website is at your own risk. If reproducing diagrams that include third party information, please cite both the Africa Groundwater Atlas and the third party sources. Please see the [[Africa Groundwater Atlas Terms of Use | Terms of use]] for more information.

==Geographical Setting==

[[File:Ethiopia_Political.png | right | frame | Ethiopia. Map developed from USGS GTOPOPO30; GADM global administrative areas; and UN Revision of World Urbanization Prospects. For more information on the map development and datasets see the [[Geography | geography resource page]]]]

===General===

Ethiopia's landscape includes a large highland area of mountains and dissected plateaus, divided by the Rift Valley, which runs generally southwest to northeast and is surrounded by lowlands, steppes, or semi-desert. This large diversity of terrain has led to wide variations in climate, soils and natural vegetation.

{| class = "wikitable"
|-
|Capital city || Addis Ababa
|-
|Region || Eastern Africa
|-
|Border countries || Eritrea, Sudan, South Sudan, Kenya, Somalia, Djibouti
|-
|Total surface area* || 1,104,300 km<sup>2</sup> (110,430,000 ha)
|-
|Total population (2015)* || 99,391,000
|-
|Rural population (2015)* ||80,125,000 (81%)
|-
|Urban population (2015)* || 19,266,000 (19%)
|-
|UN Human Development Index (HDI) [highest = 1] (2014) ||0.4418
|}

<nowiki>*</nowiki> Source: [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en FAO Aquastat]

===Climate===

The highlands in the central-west of the country are temperate, with high annual rainfall, or tropical savannah, with distinct dry and wet seasons. In the lowland areas in the east, the climate is arid steppe or arid desert, and is significantly hotter and drier.

[[File:Ethiopia_ClimateZones.png | 375x365px |Koppen Geiger Climate Zones]][[File:Ethiopia_ClimatePrecip.png | 375x365px |Average Annual Precipitation]][[File:Ethiopia_ClimateTemp.png | 375x365px |Average Temperature]]

[[File:Ethiopia_pre_Monthly.png| 255x124px| Average monthly precipitation for Ethiopia showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File:Ethiopia_tmp_Monthly.png| 255x124px| Average monthly temperature for Ethiopia showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File:Ethiopia_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File:Ethiopia_pre_Mts.png|255x124px | Monthly precipitation (blue) over the period 2000-2012 compared with the long term monthly average (red)]]

More information on average rainfall and temperature for each of the climate zones in Ethiopia can be seen at the [[Climate of Ethiopia | Ethiopia climate page]].

These maps and graphs were developed from the CRU TS 3.21 dataset produced by the Climatic Research Unit at the University of East Anglia, UK. For more information see the [[Climate | climate resource page]].

===Surface water===
{|
|-
|The highlands of Ethiopia are the source of major perennial rivers, and Ethiopia also has a number of large lakes. Lake Tana, in the north, is the source of the Blue Nile, and there are a number of other major rivers. However, apart from these major surface water features, there are hardly any perennial surface water flows in areas below 1,500 m.

The Hydrology Directorate of the Ethiopian Ministry of Water Irrigation and Energy is the responsible body for installation and maintainence of river gauges. They also manage and disseminate the resulting river discharge data.

Most hydrological records started in the 1960s following the initiation of the Blue Nile Basin Master Plan study by the USBR (United States Bureau of Reclamation). There are currently 489 operational river gauging stations in Ethiopia.

| [[File:Ethiopia_Hydrology.png | frame |Major surface water features of Ethiopia. Map developed from World Wildlife Fund HydroSHEDS; Digital Chart of the World drainage; and FAO Inland Water Bodies. For more information on the map development and datasets see the [[Surface water | surface water resource page]]]]
|}

===Soil===
{|
|-
| [[File:Ethiopia_soil.png | frame | Soil Map of Ethiopia, from the European Commission Joint Research Centre: European Soil Portal. For more information on the map see the [[Soil | soil resource page]]]]

|
|}

===Land cover===

{|

|-

|

Ethiopia is an ecologically diverse country, including deserts along the eastern border; tropical forests in the south; and extensive mountains in the north and southwest.

[[File:Ethiopia LandCover.png| frame | Land cover map of Ethiopia, from the European Space Agency GlobCover 2.3, 2009. For more information on the map see the [[Land cover | land cover resource page]]]]

|

|}

===Water statistics===

{| class = "wikitable"
| || 2001 ||2005||2012||2014||2015||2016
|-
|Rural population with access to safe drinking water (%) || || || || ||48.6 ||
|-
|Urban population with access to safe drinking water (%) || || || || ||93.1 ||
|-
|Population affected by water related disease ||No data ||No data ||No data ||No data ||No data ||No data
|-
|Total internal renewable water resources (cubic metres/inhabitant/year) || || || || 1,227|| ||
|-
|Total exploitable water resources (Million cubic metres/year) ||53,000 || || |||| ||
|-
|Freshwater withdrawal as % of total renewable water resources || || || || || ||
|-
|Total renewable groundwater (Million cubic metres/year) || || || || ||20,000 ||
|-
|Exploitable: Regular renewable groundwater (Million cubic metres/year) || ||2,600 || || || ||
|-
|Groundwater produced internally (Million cubic metres/year) || || || || 20,000|| ||
|-
|Fresh groundwater withdrawal (primary and secondary) (Million cubic metres/year) ||No data ||No data ||No data ||No data ||No data ||No data
|-
|Groundwater: entering the country (total) (Million cubic metres/year) || || || || || ||
|-
|Groundwater: leaving the country to other countries (total) (Million cubic metres/year) ||No data ||No data ||No data ||No data ||No data ||No data
|-
|Industrial water withdrawal (all water sources) (Million cubic metres/year) || ||51.1 || || || ||
|-
|Municipal water withdrawal (all water sources) (Million cubic metres/year) || || 810|| || || ||
|-
|Agricultural water withdrawal (all water sources) (Million cubic metres/year) || || || || || ||9,687
|-
|Irrigation water withdrawal (all water sources) (Million cubic metres/year) || || || || || ||9,000
|-
|Irrigation water requirement (all water sources) (Million cubic metres/year) ||1,475 || || || || ||
|-
|Area of permanent crops (ha) || || || ||1,140,000 ||||
|-
|Cultivated land (arable and permanent crops) (ha) || || || ||16259 || ||
|-
|Total area of country cultivated (%) || || || ||14.72 || ||
|-
|Area equipped for irrigation by groundwater (ha) ||2,611 || || || || ||
|-
|Area equipped for irrigation by mixed surface water and groundwater (ha) ||No data ||No data ||No data ||No data ||No data ||No data
|}

Source and more statistics at: [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en FAO Aquastat].

==Geology==

The following section provides a summary of the geology of Ethiopia. More detailed information can be found in the key references listed below: many of these are available through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].

The geology map on this page shows a simplified version of the geology of Ethiopia at a national scale (see the [[Geology | geology resource page]] for more details).

[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Ethiopia geology and hydrogeology map'''].

[[File:Ethiopia_Geology3.png | center | thumb| 500px | Geology of Ethiopia at 1:5 million scale. Developed from USGS map (Persits et al. 2002). For more information on the map development and datasets see the [[Geology | geology resource page]]. [https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html Download a GIS shapefile of the Ethiopia geology and hydrogeology map].]]

{| class = "wikitable"
|+ Geological Environments
|Key Formations||Period||Lithology||Thickness and important structural features
|-
!colspan="4"| Igneous - volcanic
|-
|Rift volcanics
||Quaternary
||Rift related, unwelded and welded pyroclastics and basalts. Composed of ash, pumice, ignimbrites and pyroclastics.
||Thickness reaches 500 metres; multiple sets of faults, fractures and volcanic landforms, isolated volcanoes and cones, calderas and craters
|-
|Quaternary plateau basalts
||Quaternary
||Scoraceous basalts, mostly vesicular and scoraceous. Have a limited lateral extent.
||Associated with central eruptions from volcanic centres on the plateau; mainly associated with shields.
|-
|Shield volcanics
||Miocene (Tertiary)
||Basalts intercalated with minor acid volcanic rocks (eg rhyolites) and trachytes. The basal diameters of the shields range from 50 to 100 km. They radiate from a peak, and dip at an angle of 5°.
||500 metres; broad based (up to 100 km) shields dotting the Ethiopian plateau
|-
|Aiba, Alaji and Termaber formations (Upper Basalts)
||Oligo-Miocene (Tertiary)
|Basalts with intercalations of rhyolites and ignimbrites towards the top part. Can be associated with shield volcanics. Mostly massive basalt, but columnar jointed layers are common. Layers of acidic rocks, rhyolites and tuffs are also common. Paleosol layers may be visible between the contact of this unit with the the underlying Ashangie Formation.
||Thickness 1000 metres. Typically forms flat topped, uniform plateau areas, with cliffs at plateau edges.
|-
|Ashangie Formation (Lower Basalts)
||Oligocene (Tertiary)
||Deeply weathered, brecciated basalts
||500 metres, forms rugged terrain

|-
!colspan="4"| Sedimentary - Miocene (Tertiary) to Recent
|-
|Alwero Formation (largely consolidated) and associated unconsolidated sediments
||Miocene (Tertiary) to Recent
||
#Holocene alluvial sediments
#:Alluvial sediments composed of diatomites, red beds, fluvial materials and paleosols. These were probably developed during the Holocene climate fluctuations. Up to 400 metres thick.
#Quaternary alluvio-lacustrine sediments
#:Quaternary to recent alluvial sediments, lacustrine sediments, river terraces, volcanoclastics, colluvial and talus slopes, fluviatile and deltaic sediments, elluvials and soils. These localised deposits are present in central Ethiopia, southern and north western Ethiopia. Up to 500 metres thick.
#Pliocene (Tertiary) Alwero Formation
#: Sandstones
||1 km?. The Basin forms part of the Blue Nile rift in South Sudan and extends toward the west
|-
!colspan="4"| Sedimentary - Eocene
|-
|Auradu and Taleh formations - carbonate and evaporite rocks
||Eocene (Tertiary)
||Interbedded limestone, evaporite (anhydrite, gypsum) and shale
||500 metres; karst features observed
|-
!colspan="4"| Sedimentary - Upper Cretaceous
|-
|Jessoma Sandstone
||Upper Cretaceous
||Detrital, poorly cemented sandstone
||500 metres; poor surface drainage and plain forming- extends south up to Mogadishu in Somalia
|-
!colspan="4"| Sedimentary - Lower Cretaceous
|-
|Korahe Formation
||Lower Cretaceous
||Marine deposits; interbedded gypsum, shale, anhydrite, dolomite, limestone and sandstone
||Not known
|-
!colspan="4"| Sedimentary - Jurassic
|-
|Gabredarre, Hamanile, Urandab and Antalo formations - limestones
||Jurassic
||Dominantly limestone (75%) with some shale, marl and gypsum intercalations

The '''Gabredarre Formation''' includes oolitic limestones, marls and some gypsum. It is horizontally bedded and characterised by karst features, including solitary caves such as the famous Sofomar caves. The limestones of the Sofomar caves region have the highest degree of karstification of Ethiopia's carbonate rocks. The Gabredarre Formation has limestone cliffs that are moderately jointed and have intercalations of sand, marl and gypsum beds. The Gabredarre Formation grades down to the underlying Urandab Formation, which is the equivalent of the Antalo Limestone.

The '''Hamanile Formation''' consists of organogenic and oolitic limestones with shale and sandstone. The limestones are well jointed. The Haminile limestone plateau occurs on the Dolo to Negele Borena road around Bidre and consists of a marly, fractured, thinly (~1m) bedded limestone. Around Negele Borena the Hamanile limestone formation can be classified into at least five sub-units characterized by variable lithologies and intercalations. The succession is thinnest in the area of Negele town. The maximum thickness is about 700 m in the area of Filtu.
||1000 metres
|-
|Adigrat Sandstone
||Jurassic
||Highly cemented sandstone. The top part has been altered by heating from Cenozoic volcanism.
||700 metres
|-
!colspan="4"| Precambrian Mobile/Orogenic belt
|-
|Precambrian: Medium-High grade Mozambique belt in south and west Ethiopia
||Proterozoic
||Paleoproterozoic metasediments and gneiss and pre- and syn-tectonic granites. Generally high grade metamorphic rocks are interbedded with low grade metamorphic rocks
||This part of the basement in Ethiopia, unlike the basement in much of central Africa, has undergone multiple episodes of deformation and orogenesis.
|-
|Precambrian: Low grade Arabian Nubian Shield in Northern Ethiopia
||Proterozoic
||A transition zone between low grade volcano sedimentary succession and mafic ultramafic complexes of the Arabian Nubian Shield. The key lithologies are metavolcano sedimentary rocks and post-tectonic granite intrusive igneous rocks.
||
|-
|}

==Hydrogeology==

The most important aquifers in Ethiopia are formed by '''unconsolidated Quaternary sediments'''; '''Tertiary-Quaternary volcanic rocks'''; and '''Mesozoic consolidated sedimentary rocks'''. Basement aquifers are also important locally. A summary of these aquifers and their physical and chemical characteristics is in the tables below. More detailed information is available in the references listed below each table: many of these are available through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].

The hydrogeology map on this page shows a simplified version of the type and productivity of the main aquifers at a national scale (see the [[Africa Groundwater Atlas Hydrogeology Maps | hydrogeology Map]] resource page for more details).

[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Ethiopia geology and hydrogeology map'''].

Other hydrogeological maps from different sources have been produced and are available in different formats. Some can be viewed on the [http://www.bgr.de/app/fishy/whymis/index.php?&type=country&id=ETH WHYMAP] website.

[[File:Ethiopia Hydrogeology3.png | center | thumb| 500px| Hydrogeology of Ethiopia at 1:5million scale. For more information on how the map was developed see the [[Africa Groundwater Atlas Hydrogeology Maps | hydrogeology map]] resource page. [https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html Download a GIS shapefile of the Ethiopia geology and hydrogeology map].]]

====Unconsolidated====
<div id="Unconsolidated: Quaternary"></div>

{| class = "wikitable"
|Named Aquifers||Aquifer Productivity||General Description||Water quality
|-
|Alluvial sediments
||Afar Region - High Productivity. Northern Ethiopia - Low Productivity.
||Afar Region: alluvial deposits in floodplains have moderate to high permeability, with measured transmissivity from 1-500 m²/day and yields of up to 20 l/s. These aquifers can be unconfined and confined; they vary in thickness from 0 - 400 metres; water table depth is typically in the range 1 to 60 metres; typical borehole depth is 100 m; salinity is very variable.

In the Holocene alluvial aquifer borehole yields of 0.1 to 1 l/s have been recorded. Water levels are usually less than 5 m below ground surface.

Northern Ethiopia: alluvial sediments overlying basement rocks can store appreciable volumes of water and are characterised by high permeability and high water infiltration capacity. They are typically shallow and have limited lateral extent, and form perched aquifers. Springs and hand-dug wells are common, with recorded yields ranging between 0.05 l/s and 0.17 l/s.
||Variable salinity
|-
|Alluvio-lacustrine sediments
||Variable productivity, but can be highly productive in places
||These sediments have highly variable permeability. Fine sand deposits have the highest permeability, with some boreholes providing more than 10 l/s with minimal drawdown. Transmissivities range up to 700 m²/day and specific yields are of the order of 3.2 l/s/m. In several places higher transmissivities have been noted. For example, a 150 m deep borehole in alluvio-lacustrine deposits at the foot of the southern plateau has a transmissivity of 3012 m²/day. These aquifers can be both unconfined and confined; they vary in thickness from 0 to 400 metres; water table depth is typically in the range 1 to 60 metres; and the typical borehole depth is 100 m.

Fine-grained sands interbedded with massive volcanic tuffs and fine ash are known to have low productivity in many places (e.g. in the central Ethiopian Rift). In the eastern part of the country the total thickness of these sediments can reach about 300 m. In most of the outcrops, they consist of conglomerates, sandstone and mudstone, which are gypsiferous and locally bear saline groundwater.
||Variable salinity
|-
|Quaternary Alluvial Aquifers within Lake Tana basin
||Moderate to High Productivity
||These occur dominantly in the eastern part of the basin following the lower Rib and lower margin of Gumera and Fogera plain (East of Lake Tana). They also cover a significant area of the north part of the basin at the lower part of the Megech and Western shore of Lake Tana. However, the distribution of alluvial sediments is limited compared to the volcanic aquifers. The deposits vary in thickness from 1 to 400m. The aquifers can be unconfined or confined. Water table depth is typically in the range 1 to 60 metres, and typical borehole depth is 100 m.

The productivity of this aquifer is controlled by the intergranular permeability of the unconsolidated gravels, sand and clay. They are typically high productivity aquifers, with boreholes up to 60 m depth recorded as yielding more than 6 l/s.

The previous investigation aided with drilling on the lake floor shows the occurrence of indicates stiff clay up to 80 m depth.
||Variable salinity
|-
|Wadi bed aquifers
||Moderate to High Productivity
||Although localised, these intergranular aquifers have significant groundwater potential in water scarce arid and desert settings. Wadi bed length exceeds 30 000 km across Ethiopia, and total groundwater storage in these aquifers could be as much as 3 billion cubic metres. The most important wadi aquifers, which support the livelihoods of millions of people living a pastoral lifestyle, include those in Borena, Lower Omo, Ogaden, the Western Lowlands bordering Sudan, and in the Afar depression. The most productive wadi bed aquifers are those dominated by sandy and gravelly sediments with a low proportion of clay.

One of the highest yielding recorded boreholes abstracting from a wadi bed aquifer is the El-Gof borehole, which taps an intergranular sand and gravel aquifer, overlain by lacustrine sediments, and has a yield of 5 l/s. Other boreholes have recorded discharges of 0.5 l/s to 8 l/s.

An important source of groundwater in areas with little surface water
||Variable salinity
|-
|Talus slope, landslide bodies, alluvial terraces
||Moderate Productivity
||These deposits form small outcrops 0.5 to 2 km² in area. Permeability is enhanced in areas where the material is loosely packed. Groundwater from mountain areas flows towards the talus slope and landslide deposits, from where springs commonly emerge. Typical spring yields are 1 to 2 l/s. These aquifers with readily available groundwater discharges support several villages in areas of relatively gentle slopes and good soil development. Recharged from groundwater flowing from higher elevation.
||Variable salinity
|}

'''Key references for Quaternary unconsolidated aquifers of Ethiopia''' are Alemneh (1989); Chernet (1993) and Hadwen et al. (1973) (for more details see [[Hydrogeology of Ethiopia#Hydrogeology: key references | Key Hydrogeology References]]).

====Igneous - Volcanic====
{| class = "wikitable"
|Named Aquifers||Aquifer Productivity||General Description||Water quality
|-

|Rift volcanics
||Moderate Productivity
||Borehole yields generally from 1 to 5 l/s. In some conditions the aquifer is confined, leading to artesian conditions. Both direct rainfall and indirect (eg from river beds) recharge is common.
||High fluoride and salinity, often exceeding WHO limits.
|-
|Quaternary plateau basalts
||High Productivity
||The most extensive occurrence is in the Lake Tana Basin, where these form a highly productive, fractured aquifer, with borehole yields reaching 20 l/s (there are other records of borehole yields of between 5 and 100 l/s), and groundwater discharge to rivers and springs. Elsewhere in Ethiopia the Quaternary volcanics are highly productive but have dual fracture-intergranular porosity. Direct and indirect recharge occurs.
||Good water quality: generally bicarbonate type, low salinity, low fluoride.
|-
|Shield volcanics
||
||This aquifer can be up to 500 m thick. Groundwater discharge occurs through springs, which are common at the foot of the shield areas. The intercalation of volcanic ash with basalt forms a dual porosity and permeability groundwater system: groundwater storage is focussed in ash layers, while groundwater flow is focussed through fractures in the basalt layers. Shield areas dominated by acid volcanic rocks show lower groundwater potential (e.g. in the Bale Massif). The aquifer is typically unconfined to semi confined. The depth to water ranges from 5 to 60 m, and borehole depths are typically 60 to 150 metres. Recharge occurs through fractures in highland areas.
||Good water quality: generally bicarbonate type, low salinity, low fluoride.
|-
|Upper basalt aquifer (Aiba, Alaji and Termaber formations)
||High Productivity
||This aquifer forms the most productive of the volcanic aquifers in Ethiopia. It is typically unconfined to semi-confined and often artesian. Groundwater discharge occurs to wetlands and to springs on cliffs. The aquifer thickness ranges from 50 to 1000 m. The depth to water table varies from 0 to 250 metres. Borehole depths are typically from 100 to 150 m. Borehole yields are generally up to 20 l/s.

The Aiba Formation has dual porosity, with groundwater occurring in joints, fractures and scoriaceous layers. Deep boreholes show the presence of narrow but extensive fracture zones with high permeability and low storage. Transmissivity varies between 0.5 and 1400 m²/day. Borehole yields range from 5 to 150 l/s.

Pumping test analysis and well logs from the Termaber Formation show that it is dominated by fracture flow. Recharge occurs vertically through the soil zone and fractures in the rocks.
||Good water quality: generally bicarbonate type, low salinity, low fluoride.
|-
|Lower basalt aquifer (Ashangie Formation)
||Low to High Productivity
||These rocks are characterised by rugged topography with dissected and irregular morphology. The rocks are deformed, and in their northern section dip at up to 40°. They are thinly bedded, and in several areas are brecciated. Field evidence shows that the brecciated parts are characterized by lower permeability. The rocks are typically deeply weathered, when they are reddish in colour, but generally have low permeability. Both primary (vesicle) porosity and secondary (fracture) porosity have been modified and reduced by secondary mineralisation (e.g. by calcite, zeolite and silica).

In more detail, the Ashangie Formation can be divided into three zones:

1) an upper layer, with gentle topographic slopes. Mostly scoriaceous, with several thin beds of clay soils. Recharge occurs vertically through this layer to the underlying layers. Springs are rare, and most groundwater discharge occurs as diffuse seepage on slopes, often contributing to landslides.

2) a thinner middle, more resistant layer, which often forms cliffs. When exposed at the ground surface by erosion, this can form locally extensive plateau areas, such as around the Upper Tekeze plains, Lalibela and the Belesa plain. Typically has higher groundwater productivity.

3) a lower layer, also with gentle slope. Mostly scoriaceous, with several thin beds of clay soils. Often contains cross-cutting dykes which are conduits for groundwater convergence and discharge.

The aquifer thickness varies up to 500 m. The rugged topography means that the aquifer is not laterally extensive. Depressions in the rugged terrain are areas of groundwater discharge.

The aquifer is usually unconfined to semi-confined. Typical borehole yields are between 0.5 and 20 l/s. Transmissivity ranges between 0.5 and 85 m²/day. The water table depth is typically between 100 and 200 m, and borehole depths are typically 150 to 200 m.

The contact between this unit and the upper basalt above is characterised by spring discharge.
||Good water quality: generally bicarbonate type, low salinity, low fluoride.
|}

'''Key references for volcanic aquifers of Ethiopia''' are Kebede (2013) and Ayenew et al. (for more details see [[Hydrogeology of Ethiopia#Hydrogeology: key references | Key Hydrogeology References]]).

====Mesozoic Consolidated Sedimentary Aquifers with Fracture and Intergranular Flow====

Notable hydrogeologic and geologic features of Mesozoic sedimentary rocks of Ethiopia are:

- Uplifting and formation of tabular plateaus;

- deep incision by river gorges;

- absence of or limited karstification in carbonate rocks;

- absence of regional folding and flexures at the margins of the units; and

- extensive cover by younger volcanic rocks.

These features contrast with typical sedimentary basins elsewhere in Northern and Eastern Africa. In contrast to the sedimentary basin aquifers of northern and Sahel Africa, structural traps (such as synclines formed by compressional deformation) are uncommon, leaving little room for large volume groundwater storage.

{| class = "wikitable"
|Named Aquifers||Aquifer Productivity||General Description||Water quality
|-
|Hamanile, Gabredarre and Antalo formations (Jurassic limestones)
||High Productivity
|| The '''Gabredarre Formation''' is characterised by karst features, including caves. The limestones of the Sofomar caves region have the highest degree of karstification of Ethiopia's carbonate rocks. The aquifer has moderate permeability and productivity.

The '''Hamanile Formation''' limestones are well jointed with moderate to high permeability. Evidence from boreholes in highland and midlands areas, where the aquifer crops out, shows that groundwater levels can be very deep: for example, more than 200 m below ground level between Filtu and Negele. Where the water table is shallower, the Hamanile limestones form relatively productive aquifers.

In general, these aquifers are typically 500 to 1000 m thick, and are unconfined to semi-confined. The water table is usually 200 to 400 m deep; typical borehole depth is 300 m.

In high rainfall highlands, recharge could reach 200 mm/yr. In arid regions it varies between 10 mm/yr and 50 mm/yr.
||Good quality water generally. However, high concentrations of dissolved salts, including sodium, chloride and/or sulphate, occur due to reaction with abundant minerals in evaporite beds, and salinity can reach 3 mg/l.
|-
|Adigrat Formation (Jurassic sandstone)
||Moderate Productivity
||The highly cemented '''Adigrat Formation''' has low primary porosity, and the top part has been altered by heating by Cenozoic volcanism. Fracturing has created secondary porosity and permeability. The emergence of springs at the contact of the Adigrat sandstone and the overlying volcanic rocks is indicative of the low permeability of the Adigrat Formation.

This aquifer is typically 200 to 1000 m thick and is unconfined to semi-confined. The water table is usually 200 to 400 m deep; typical borehole depth is 300 m.

In highlands areas with high rainfall, recharge could reach 200 mm/yr. In arid regions it varies between 10 mm/yr and 50 mm/yr.
||Very good quality water
|}

'''Key references for Mesozoic sedimentary aquifers of Ethiopia''' are BSEE (1973), Chernet (1993), Hadwen et al. (1973), Haile et al (1996) and Kebede (2013) (for more details see [[Hydrogeology of Ethiopia#Hydrogeology: key references | Key Hydrogeology References]]).

====Precambrian Basement====
{| class = "wikitable"
|Named Aquifers||Aquifer Productivity||General Description||Water quality
|-
|Precambrian basement aquifers of Southern Ethiopia and Northern Ethiopia; Crystalline Basement aquifers of Western Ethiopia
||Very Low to Low Productivity.
||'''Basement aquifers in general'''

The productivity of basement aquifers in Ethiopia largely depends of the development of regolith (weathered rock) amd the density of fractures. In turn, these are partly controlled by the type or grade of metamorphic rock that forms the basement. Less important controls on groundwater occurrence are the sustainability of recharge; and topography. Groundwater in the basement aquifers occurs in shallow regolith (weathered rock) basins.

Borehole yields from the most productive boreholes in basement aquifers are generally less than 0.1 l/s. Spring discharges in the basement complex are of the order of 1 l/s. Generally, basement aquifers in western and south-central parts of Ethiopia are productive, and the lowest productivity basement aquifers are located in northern Ethiopia and the Borena lowlands (near the southern border).

The basement aquifers are unconfined. Aquifer (regolith) thickness varies from 0 to 60 m (thinner in northern Ethiopia and thicker in western Ethiopia - see below). The deepest known borehole struck water at 100 m. The water table is typically 2 to 60 m deep. Boreholes tend to be 60 to 120 m deep.

;Regional details:
:'''Northern Ethiopia''': the basement rocks of Northern Ethiopia have low groundwater potential. Groundwater occurs generally in fractures in the upper few metres of the unweathered rocks; in very thin regolith layers; and in patches of overlying alluvial sediments in river valleys (see the [[Hydrogeology of Ethiopia#Unconsolidated | Unconsolidated]] section for further information).
:'''Southern Ethiopia''': groundwater in the basement rocks is stored in, and transmitted through, both regolith layers and fractures. There is variable fracturing and regolith development. Borehole yields range from 0.13 to 0.33 l/s.
:'''Western Ethiopia''': the crystalline basement aquifers of Western Ethiopia have better groundwater storage than in other areas. This higher groundwater potential is related to high rainfall that supports high recharge; to a relatively thick regolith which favours groundwater storage; and to rugged undulating topography which favours accumulation of weathering products in depressions and flat plains allowing groundwater storage and circulation. The average borehole yield is 5 l/s (Bako & Abakoran). The hydraulic conductivity of this aquifer varies from 0.12 m/day to 2.3 m/day.

Recharge varies from 10 to 250 mm/yr depending on rainfall regime
||Good quality
|}

'''The key reference for basement aquifers of Ethiopia''' is Kebede (2013) (for more details see [[Hydrogeology of Ethiopia#Hydrogeology: key references | Key Hydrogeology References]]).

===Recharge===

Recharge over Ethiopia is extremely variable. It varies from nearly 0 to 300 mm/yr. Nearly 60% of aquifers receive indirect recharge from floods, mountain runoff, as well as fast recharge from high rainfall events. Diffuse recharge is limited to the plateau region which accounts for around 30% of the country.

The geological uplift in the Cenozoic which led to erosion and dissection of the aquifers into smaller size units, has resulted in generally low storage compared to large sedimentary basins elsewhere in Africa. The storage to recharge ratio is around 28 years (Kebede, 2013).

===Groundwater Quality===

Groundwater quality is highly variable across Ethiopia, from fresh waters in many of the springs flowing from basement aquifers, to more saline waters in volcanic aquifers in parts of the Rift Valley and sedimentary aquifers of the plains.

The key natural groundwater quality issues are:

;'''Fluoride'''.

Fluoride has long been a recognised health concern in Ethiopia. Concentrations of fluoride in groundwater that are higher than the WHO guideline value of 1.5 mg/l have been found across Ethiopia, but are concentrated in the Rift Valley, linked to the volcanic geology. Groundwater fluoride values of greater than 10 mg/l have been found in some areas ([http://nora.nerc.ac.uk/id/eprint/516312/1/Ethiopia.pdf Smedley 2001]). As a result of the long-term use of high-fluoride drinking water, both dental and skeletal fluorosis are known to occur in populations from the Rift Valley. However, more research is needed on the links between geology, hydrogeology, fluoride concentrations and fluorosis in order to target interventions.

;'''Salinity'''.

High values of total dissolved salts in volcanic aquifers in the Rift Valley are linked to the influence of geothermal waters. Increased salinity in many groundwaters in sedimentary aquifers in the south, southeast and northeast of the country, is linked to the dissolution of evaporite minerals.

Key references for more information on groundwater quality in Ethiopia are:

British Geological Survey/WaterAid. 2001. [http://www.wateraid.org/~/media/Publications/groundwater-quality-information-ethiopia.pdf Groundwater Quality: Ethiopia]. Leaflet.

===Groundwater Status===

;Groundwater quantity
Annual renewable groundwater resources are estimated at around 36,000 million cubic metres (36 billion cubic metres) , with estimates of total groundwater storage varying from 1,000 to 10,000 billion m³.

;Groundwater guality:
An estimated 30% of groundwater storage is not available for direct use because of high salinity and/or high fluoride.

;Groundwater-Surface Water Interaction:
- There are a number of groundwater dependent surface waters, including wetlands and lakes.
- Wetlands are increasingly threatened by deepening, widening and propagating gullies as well as by infestation by invasive weeds

;Groundwater Dependent Ecosystems
There is low recognition at government level of the fact that wetlands are groundwater dependent.

==Groundwater use and management==

=== Groundwater use===

Some 80% of the total national water supply comes from groundwater.

Kebede (2013) gives national estimates of groundwater abstraction volumes. Groundwater provides most of the water for domestic supply (90%) and industrial use (95%).

To date only a very small proportion of irrigation demand (<1%) comes from groundwater, including small well irrigation by smallholder farmers, but some larger commercial irrigation schemes are pioneering the use of groundwater. Groundwater use for livestock watering is unknown. More hydrogeological research may help increase the use of groundwater for irrigation, for example in proving the existence of a large enough resource that can be sustainably abstracted.

Groundwater sources in Ethiopia consist of:
*Boreholes
*Hand dug wells
*Improved cold springs
*River bed excavations/pits
*Haffirs
*Traditional Ella wells (very large diameter wells)
*Bircados

=== Groundwater management===

There are currently no regional or national groundwater level or quality monitoring programmes, and relatively little formal registration of boreholes and other water abstraction points.

The key groundwater institutions, and their roles, are:

*Ministry of Water Irrigation and Energy- Regulatory, policy, financing, planning, maintenance of information base

*Geological Survey of Ethiopia- Exploration and Mapping

*Ministry of Forestry and Environment: Reviewing possible impacts of national investments on groundwater quality and quantity; Selected strategic environmental assessments – linked to groundwater management plans

*Agricultural Transformation Agency- Shallow groundwater mapping and management policy

*Regional Water Bureaus- Regulatory, policy, financing and planning

*Water Works Enterprises- Study, Design, Supervision and Development

*Regional Ministry of Forestry and Environment: Licensing and Impact assessment of investment on groundwater

*River Basin Organizations: Allocation and supplies

*Water User Associations: Local regulation and allocation; formal and informal

*Drillers' Association

*Technical and vocational Schools (TVETs): training human power in groundwater development , low skill

There is a limited legal framework for groundwater management, but the regulations are not systematically implemented. No regulatory provision exists to protect vulnerable areas. The report “Groundwater Management framework document (MWR, 2010)” includes the following regulatory provisions:

*No person shall be engaged in the drilling or rehabilitating of water wells without a permit duly issued by the Ministry or his designee.
*Any person who wants to have water well drilled shall first acquire a permit to do so from the Ministry or his designee before entering a contract for this purpose with a water well drilling or rehabilitating contractor. Applications made to have a water well drilling or rehabilitating contractor. Applications made to have water well drilled must be accompanied with the design and specifications of such well.
*All water well drillers and rehabilitators shall, before entering in to a contract to drill water well, first ensure that the Ministry or his designee has approved that such well be drilled.
*All persons who want to have a water well drilled or rehabilitated shall, before entering in to a contract to have such water well drilled or rehabilitated, first ensure that the driller or rehabilitator has a permit to undertake the drilling or rehabilitating or water wells.
*A well driller or rehabilitator shall, within three months of completing a well drilling or rehabilitation, submit to the Ministry or his designee a technical report – that includes information about the drilling, construction and rehabilitation process, the geological and electrical log, yield tests, laboratory tests, problems encountered during drilling, construction and rehabilitation, pump installed.

Informal local water user organisations exist for most small-scale traditional water schemes, including groundwater, that operate on more than an individual/household level, and typically do not have legal recognition or support. For formal and most modern schemes, there is usually a formal statutory water user association or irrigation cooperative.

=== Groundwater data===

Maps, data and reports from the [https://gw4e.acaciadata.com/home '''Groundwater mapping for climate resilient WASH in arid and semi-arid areas of Ethiopia'''] project (2018-2020) can be visualized and downloaded from a public webservice system, the [https://gw4e.acaciadata.com/home '''GW4E viewer''']. This includes harmonized geological maps, groundwater suitability maps and socio-economic maps on a scale of 1:250,000 for eight clusters in Ethiopia, and 1:50,000 hydrogeological maps and 1:10,000 drilling maps for target kebeles.

=== Transboundary aquifers===

The major transboundary aquifers in Ethiopia are:

*The unconsolidated sedimentary aquifers of Gambella (Upper Blue Nile) and Alwero Sandstone: Ethiopia and South Sudan
*The Bulal Basalt aquifer: Ethiopia and Kenya
*The Hanle Graben aquifer: Djibouti and Ethiopia
*The Sedimentary Basin of Ogaden: Ethiopia and Somalia

No management system exists specifically pertaining to transboundary aquifers. Conflict over water sources in general is common among pastoralists in the border region of Ethiopia and Kenya.

==Groundwater Projects==

Information on particular groundwater projects in Ethiopia, including links to project results and outputs, can be found on the [[Ethiopia Groundwater Projects | Ethiopia groundwater projects]] page.

==References==

Many of the references below, and others relating to the hydrogeology of Ethiopia, can be accessed through the [https://www.bgs.ac.uk/africagroundwateratlas/atlas.cfc?method=listResults&title_search=&titleboolean=AND&author_search=&category=&child_category=&country=ET African Groundwater Literature Archive].

===Geology: key references===

Beyth M. 1972. The Geology of Central Western Tigre, Ethiopia. University of Bonn, p. 155.

EGS. 1996. Geological map of Ethiopia at 1:2000000 scale. Ethiopian Geological Survey, Addis Ababa, Ethiopia

Davidson A. 1983. The Omo River Project. Reconnaissance geology and geochemistry of parts of Illubabor, Kefa, Gemu Gofa and Sidamo, Ethiopia. Ethiopian Institute of Geological Surveys Bull 2, 89 pp.

Kazmin V, Shiferaw A and Balcha T. 1978. The Ethiopian basement: stratigraphy and possible manner of evolution. GeologischeRundschau 67, 531–548.

Kieffer B, Arndt N, Lapierre H et al. 2004. Flood and Shield Basalts from Ethiopia: Magmas from the African Superswell. J of Petrology 45:793-834

Le Turdu C, Tiercelin JJ, Gibert E et al. 1999. The Ziway–Shala lake basin system, Main Ethiopian Rift: influence of volcanism, tectonics, and climatic forcing on basin formation and sedimentation. Palaeogeography, Palaeclimatology and Palaeoecology 150: 135–177.

Mohr P. 1973. Crustal deformation rate and the evolution of the Ethiopian rift. In: Tarling DH, Runcorn SK (eds) Implications of continental drift to the earth sciences. Academic Press, London, pp 767–776

Mohr P. 1983. Ethiopian Flood Basalt Province. Nature 303:577- 584.

Mohr P and Zanettin B. 1988. The Ethiopian flood basalt province. In: Macdougall, J. D. (ed.) Continental Flood Basalts. Dordrecht: Kluwer Academic, pp. 63---110.

Rochette P, Tamrat E, Feraud G et al. 1998. Magnetostratigraphy and timing of the Oligocene Ethiopian Traps. Earth and Planet.Sci. Lett, 164: 497-510.

Taddesse T, Hoshino M, Sawada Y. 1999. Geochemistry of low-grade metavolcanic rocks from the Pan-African of the Axum area, northern Ethiopia. Precambrian Research 99: 101–124

USBR. 1964. Land and water resources of the Blue Nile basin, Ethiopia. United States Bureau of Reclamation, Main report, Washington.

WoldeGabriel G, Walter RC, Aronson JL. 1992. Geochronology and distribution of silicic volcanic rocks of Plio-Pleistocene age from the central sector of the Main Ethiopian Rift. Quat. Int. 13–14, 69–76.

Zanettin B, Justin-Visentin E. 1974. The volcanic succession in central Ethiopia, the volcanics of the western Afar and Ethiopian Rift margins. Univ. Padova Inst. Geol. Mineral. Mem. 31, 1–19.

===Hydrogeology: key references===

Alemneh S. 1989. Hydrogeology of Yabello sheet (NB37-14). Ethiopian Geological Survey report number 307. Addis Ababa, 40pp.

Awulachew S. 2010. [https://agriknowledge.org/downloads/j38606956 Irrigation potential in Ethiopia: Constraints and opportunities for enhancing the system]. IWMI.

Ayenew T, Demli M and Wohnlich S. DATE. Occurrence of groundwater in Ethiopian volcanic terrain. Journal of Africa Earth Sciences, 52 (3), 97–113.

BCEOM. 1999. Abay River Basin integrated master plan, main report, Ministry of Water Resources, Addis Ababa.

Belete Y, Alemirew D, Mekonen A et al. 2004. Explanatory notes to the hydrogeological and hydrochemical maps of the Asosa-Kurmuk Area (NC36-7 West of Assosa and NC36-8 Assosa sheets). Geological Survey of Ethiopia, Addis Ababa, 120 pp.

BSEE. 1973. The caves of Ethiopia, The 1972 British SpeleologiclaExpediation to Ethiopia. Transaction Cave Research Group of Great
Britain, 15:107-168

Chernet T. 1982. Hydrogeologic map of the lakes region (with memo) Ethiopian Institute of Geological Survey (now Ethiopian Geological Survey), Addis Ababa Ethiopia.

Chernet T. 1993. Hydrogeology of Ethiopia and water resources development Ethiopian Institute of Geological Surveys, Addis Ababa, 222pp.

Federal Democratic Republic of Ethiopia Ministry of Water Resources and GW-MATE. 2011. [http://metameta.nl/wp-content/uploads/2012/10/2011_03_08_eth_frwrk_FINALSF.pdf Ethiopia: Strategic Framework for Managed Groundwater Development].

Gasse F. 1977. Evolution of Lake Abhe (Ethiopia and TFAI), from 70,000 BP. Nature (London) 265 (5589), 42– 45.

Gasse F and Street FA. 1978. Late Quaternary lake level fluctuations and environments of the northern Rift Valley and Afar region (Ethiopia and Djibouti). Paleogeogr. Paleoclimatol. Paeoecolo. 24, 279-221

Gebru TA and Tesfahunegn GB. 2019. [https://doi.org/10.1007/s10040-018-1845-8 Chloride mass balance for estimation of groundwater recharge in a semi-arid catchment of northern Ethiopia]. Hydrogeology Journal 27 (1), 363–378. doi: 10.1007/s10040-018-1845-8.

Hadwen P. 1975. Boreholes in Ethiopia. Geological Survey of Ethiopia, Unpublished report number 29, Hydrogeology Division, Technical Memorandum 9, Addis Ababa, 22pp.

Hadwen P, Aytenfisu M and Mengesha G. 1973. Groundwater in the Ogaden. Geological Survey of Ethiopia, report number 880-551-14. 59pp.

Haile A, Kebede G and Lemessa G. 1996. Reconnaissance Hydrogeological and Engineering Geological Survey of Bikilal, Achebo and Dilbi Areas. Ethiopian Institute of Geological Survey, Report Number 880-351-06., Addis Ababa, 9pp.

Hailemeskel M. 1987. Hydrogeology of South Afar and Adjacent areas, Ethiopia. Supported by interpretation of LANDSAT imagery. Unpublished MSc thesis. International Institute for Aerial survey and Earth Sciences (ITC), Enschede, the Netherlands.

Halcrow. 2008. Rift Valley Lakes Basin Integrated Resources Development Master Plan Study Project. Main Report. Halcrow Group Limited and Generation Integrated Rural Development (GIRD) Consultants, Ministry of Water and Energy, Addis Ababa

Kebede S, Travi Y, Alemayehu T and Ayenew T. 2005. Groundwater Recharge, Circulation and Geochemical Evolution in the Source Region of the Blue Nile River, Ethiopia. Appl. Geochem. 20, 1658

Kebede S. 2013. Groundwater in Ethiopia: Features, vital numbers and opportunities. Springer, Berlin. ISBN 978 3 642 30390 6. Available to purchase at http://www.springer.com/gp/book/9783642303906

Ministry of Water and Energy. 2013. [http://metameta.nl/wp-content/uploads/2013/03/Task_Force_Report_Supplement.pdf Supplement to Task Force Report on Aquifer Management for Addis Abeba and Vicinity]. Ethiopia: Practical Framework for Managed Groundwater Development in the Greater Addis Ababa Area

MWR. 2007. Evaluation of water resources of the Ada’a and Becho plains groundwater basin for irrigation development project, Volume III: Groundwater Evaluation Report, Water Works Design and Supervision Enterprise, Addis Ababa, 188pp.

MWR. 2010. Ethiopia: Strategic Framework for Managed Groundwater Development, Report prepared by World bank - GWMate project, 77pp, Addis Ababa

Ralph M Parsons Company. 1968. Groundwater condition at Dallol, Ethiopia, Geological Survey of Ethiopia report number 880-201-01, Addis Ababa, 29pp.

Sima J. 1987. Hydrogeology and Hydrochemistry of the Bako and Ist’IfanosHayk’ areas (NB 37-9 and NB37-13), Provision Military Government of Socialist Ethiopia, Ministry of Mines and Engergy, Ethiopian Institute of Geological Surveys. Note Number 271, Addis Ababa, 65pp.

Sima J. 2009. Water Resources Management and Environmental Protection Studies of the Jemma River Basin for Improved Food Security. AQUATEST ,Geologicka Prague, Czech Republic, 220 pp.

Smedley P. 2001. [http://nora.nerc.ac.uk/id/eprint/516312/1/Ethiopia.pdf Groundwater quality: Ethiopia]. British Geological Survey.

Spate Irrigation Network Foundation. 2015. [http://spate-irrigation.org/wp-content/uploads/2015/03/OP17_Flood-wells-Ethiopia_SF.pdf Status and potential of groundwater use in Ethiopian floodplains]. Practical Note Spate Irrigation 17.

Tadesse K. 1980. Hydrogeology of Borkena River Basin, Wollo Ethiopia. Unpublished MSC thesis, Addis Ababa University, 129pp.

USBR. 1964. Land and water resources of the Blue Nile basin, Ethiopia. United States Bureau of Reclamation, Main report, Washington.

WAPCOS. 1990. Preliminary Water Resources Development Master Plan for Ethiopia, Ministry of Water Resoruces, Addis Ababa.

WWDSE. 2009. Groundwater Resources of the Upper Tekeze Basin: Resource Description, Assessment and Model, Interim Report. Water Works Design and Supervision Enterprise, Addis Ababa, 74pp.

Zerai H and Sima J. 1986. Hydrogeology and hydrochemistry of the Dire Dawa area (Sheet NC 37 12). Provisional Military Government of Ethiopia, Ethiopian Institute of Geological Survey, Note number 276, Addis Ababa, 82pp.

Return to the index pages:
[[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]


[[Category:Hydrogeology by country|e]]
[[Category:Africa Groundwater Atlas]]

Hydrogeology of Ethiopia

2020-10-06T15:10:09Z

KirstyUpton: /* Groundwater use and management */

[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Ethiopia

[[File:CC-BY-SA_logo_88x31.png | frame | This work is licensed under a [https://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License]]]

Ethiopia is one of the oldest countries in the world, having existed within similar borders to today for over 2000 years. For most of its long history its governmental system was an independent monarchy, which was overthrown in 1974. The communist military Derg government that followed was itself overthrown in 1991, since when a shaky democracy has seen several contested elections. The African Union is headquartered in Addis Ababa, Ethiopia’s capital.

Ethiopia’s economy grew rapidly between 2005 and 2010. Agriculture is a major contributor to export income and most of the population is engaged in agriculture. Most agricultural production is by small-scale farmers, but the cash-crop sector accounts for a large proportion of agricultural exports, with the most important being coffee: Ethiopia is the largest coffee exporter globally. The country also has large mineral resources, with gold a major export commodity, but they have not seen much development to date; nor has the investigation of oil potential.

Groundwater provides more than 90% of the water used for domestic and industrial supply in Ethiopia, but a very small proportion of water used for irrigation, which mostly comes from surface water. Ethiopia has vast surface water resources in lakes and rivers, which supply most of the country’s electricity through hydropower. Further expansion of hydropower capacity is planned, including the ‘Grand Ethiopian Renaissance Dam’, which is intended to become the largest hydroelectric power plant in Africa. However, the country has also suffered recurring devastating droughts, with severe impacts including famine, increased poverty and civil unrest.

==Authors==

'''Dr Seifu Kebede''', Addis Ababa University, Ethiopia

'''Addis Hailu''', University of Gondor, Ethiopia

'''Emily Crane''' & '''Brighid Ó Dochartaigh''', British Geological Survey, UK

'''Dr Imogen Bellwood-Howard''', Institute of Development Studies, UK

Please cite this page as: Kebede, Hailu, Crane, Ó Dochartaigh and Bellwood-Howard, 2018.

Bibliographic reference: Kebede, S., Hailu, A., Crane, E., Ó Dochartaigh, B.É and Bellwood-Howard, I. 2018. Africa Groundwater Atlas: Hydrogeology of Ethiopia. British Geological Survey. Accessed [date you accessed the information]. http://earthwise.bgs.ac.uk/index.php/Hydrogeology_of_Ethiopia

==Terms and conditions==

The Africa Groundwater Atlas is hosted by the British Geological Survey (BGS) and includes information from third party sources. Your use of information provided by this website is at your own risk. If reproducing diagrams that include third party information, please cite both the Africa Groundwater Atlas and the third party sources. Please see the [[Africa Groundwater Atlas Terms of Use | Terms of use]] for more information.

==Geographical Setting==

[[File:Ethiopia_Political.png | right | frame | Ethiopia. Map developed from USGS GTOPOPO30; GADM global administrative areas; and UN Revision of World Urbanization Prospects. For more information on the map development and datasets see the [[Geography | geography resource page]]]]

===General===

Ethiopia's landscape includes a large highland area of mountains and dissected plateaus, divided by the Rift Valley, which runs generally southwest to northeast and is surrounded by lowlands, steppes, or semi-desert. This large diversity of terrain has led to wide variations in climate, soils and natural vegetation.

{| class = "wikitable"
|-
|Capital city || Addis Ababa
|-
|Region || Eastern Africa
|-
|Border countries || Eritrea, Sudan, South Sudan, Kenya, Somalia, Djibouti
|-
|Total surface area* || 1,104,300 km<sup>2</sup> (110,430,000 ha)
|-
|Total population (2015)* || 99,391,000
|-
|Rural population (2015)* ||80,125,000 (81%)
|-
|Urban population (2015)* || 19,266,000 (19%)
|-
|UN Human Development Index (HDI) [highest = 1] (2014) ||0.4418
|}

<nowiki>*</nowiki> Source: [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en FAO Aquastat]

===Climate===

The highlands in the central-west of the country are temperate, with high annual rainfall, or tropical savannah, with distinct dry and wet seasons. In the lowland areas in the east, the climate is arid steppe or arid desert, and is significantly hotter and drier.

[[File:Ethiopia_ClimateZones.png | 375x365px |Koppen Geiger Climate Zones]][[File:Ethiopia_ClimatePrecip.png | 375x365px |Average Annual Precipitation]][[File:Ethiopia_ClimateTemp.png | 375x365px |Average Temperature]]

[[File:Ethiopia_pre_Monthly.png| 255x124px| Average monthly precipitation for Ethiopia showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File:Ethiopia_tmp_Monthly.png| 255x124px| Average monthly temperature for Ethiopia showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File:Ethiopia_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File:Ethiopia_pre_Mts.png|255x124px | Monthly precipitation (blue) over the period 2000-2012 compared with the long term monthly average (red)]]

More information on average rainfall and temperature for each of the climate zones in Ethiopia can be seen at the [[Climate of Ethiopia | Ethiopia climate page]].

These maps and graphs were developed from the CRU TS 3.21 dataset produced by the Climatic Research Unit at the University of East Anglia, UK. For more information see the [[Climate | climate resource page]].

===Surface water===
{|
|-
|The highlands of Ethiopia are the source of major perennial rivers, and Ethiopia also has a number of large lakes. Lake Tana, in the north, is the source of the Blue Nile, and there are a number of other major rivers. However, apart from these major surface water features, there are hardly any perennial surface water flows in areas below 1,500 m.

The Hydrology Directorate of the Ethiopian Ministry of Water Irrigation and Energy is the responsible body for installation and maintainence of river gauges. They also manage and disseminate the resulting river discharge data.

Most hydrological records started in the 1960s following the initiation of the Blue Nile Basin Master Plan study by the USBR (United States Bureau of Reclamation). There are currently 489 operational river gauging stations in Ethiopia.

| [[File:Ethiopia_Hydrology.png | frame |Major surface water features of Ethiopia. Map developed from World Wildlife Fund HydroSHEDS; Digital Chart of the World drainage; and FAO Inland Water Bodies. For more information on the map development and datasets see the [[Surface water | surface water resource page]]]]
|}

===Soil===
{|
|-
| [[File:Ethiopia_soil.png | frame | Soil Map of Ethiopia, from the European Commission Joint Research Centre: European Soil Portal. For more information on the map see the [[Soil | soil resource page]]]]

|
|}

===Land cover===

{|

|-

|

Ethiopia is an ecologically diverse country, including deserts along the eastern border; tropical forests in the south; and extensive mountains in the north and southwest.

[[File:Ethiopia LandCover.png| frame | Land cover map of Ethiopia, from the European Space Agency GlobCover 2.3, 2009. For more information on the map see the [[Land cover | land cover resource page]]]]

|

|}

===Water statistics===

{| class = "wikitable"
| || 2001 ||2005||2012||2014||2015||2016
|-
|Rural population with access to safe drinking water (%) || || || || ||48.6 ||
|-
|Urban population with access to safe drinking water (%) || || || || ||93.1 ||
|-
|Population affected by water related disease ||No data ||No data ||No data ||No data ||No data ||No data
|-
|Total internal renewable water resources (cubic metres/inhabitant/year) || || || || 1,227|| ||
|-
|Total exploitable water resources (Million cubic metres/year) ||53,000 || || |||| ||
|-
|Freshwater withdrawal as % of total renewable water resources || || || || || ||
|-
|Total renewable groundwater (Million cubic metres/year) || || || || ||20,000 ||
|-
|Exploitable: Regular renewable groundwater (Million cubic metres/year) || ||2,600 || || || ||
|-
|Groundwater produced internally (Million cubic metres/year) || || || || 20,000|| ||
|-
|Fresh groundwater withdrawal (primary and secondary) (Million cubic metres/year) ||No data ||No data ||No data ||No data ||No data ||No data
|-
|Groundwater: entering the country (total) (Million cubic metres/year) || || || || || ||
|-
|Groundwater: leaving the country to other countries (total) (Million cubic metres/year) ||No data ||No data ||No data ||No data ||No data ||No data
|-
|Industrial water withdrawal (all water sources) (Million cubic metres/year) || ||51.1 || || || ||
|-
|Municipal water withdrawal (all water sources) (Million cubic metres/year) || || 810|| || || ||
|-
|Agricultural water withdrawal (all water sources) (Million cubic metres/year) || || || || || ||9,687
|-
|Irrigation water withdrawal (all water sources) (Million cubic metres/year) || || || || || ||9,000
|-
|Irrigation water requirement (all water sources) (Million cubic metres/year) ||1,475 || || || || ||
|-
|Area of permanent crops (ha) || || || ||1,140,000 ||||
|-
|Cultivated land (arable and permanent crops) (ha) || || || ||16259 || ||
|-
|Total area of country cultivated (%) || || || ||14.72 || ||
|-
|Area equipped for irrigation by groundwater (ha) ||2,611 || || || || ||
|-
|Area equipped for irrigation by mixed surface water and groundwater (ha) ||No data ||No data ||No data ||No data ||No data ||No data
|}

Source and more statistics at: [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en FAO Aquastat].

==Geology==

The following section provides a summary of the geology of Ethiopia. More detailed information can be found in the key references listed below: many of these are available through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].

The geology map on this page shows a simplified version of the geology of Ethiopia at a national scale (see the [[Geology | geology resource page]] for more details).

[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Ethiopia geology and hydrogeology map'''].

[[File:Ethiopia_Geology3.png | center | thumb| 500px | Geology of Ethiopia at 1:5 million scale. Developed from USGS map (Persits et al. 2002). For more information on the map development and datasets see the [[Geology | geology resource page]]. [https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html Download a GIS shapefile of the Ethiopia geology and hydrogeology map].]]

{| class = "wikitable"
|+ Geological Environments
|Key Formations||Period||Lithology||Thickness and important structural features
|-
!colspan="4"| Igneous - volcanic
|-
|Rift volcanics
||Quaternary
||Rift related, unwelded and welded pyroclastics and basalts. Composed of ash, pumice, ignimbrites and pyroclastics.
||Thickness reaches 500 metres; multiple sets of faults, fractures and volcanic landforms, isolated volcanoes and cones, calderas and craters
|-
|Quaternary plateau basalts
||Quaternary
||Scoraceous basalts, mostly vesicular and scoraceous. Have a limited lateral extent.
||Associated with central eruptions from volcanic centres on the plateau; mainly associated with shields.
|-
|Shield volcanics
||Miocene (Tertiary)
||Basalts intercalated with minor acid volcanic rocks (eg rhyolites) and trachytes. The basal diameters of the shields range from 50 to 100 km. They radiate from a peak, and dip at an angle of 5°.
||500 metres; broad based (up to 100 km) shields dotting the Ethiopian plateau
|-
|Aiba, Alaji and Termaber formations (Upper Basalts)
||Oligo-Miocene (Tertiary)
|Basalts with intercalations of rhyolites and ignimbrites towards the top part. Can be associated with shield volcanics. Mostly massive basalt, but columnar jointed layers are common. Layers of acidic rocks, rhyolites and tuffs are also common. Paleosol layers may be visible between the contact of this unit with the the underlying Ashangie Formation.
||Thickness 1000 metres. Typically forms flat topped, uniform plateau areas, with cliffs at plateau edges.
|-
|Ashangie Formation (Lower Basalts)
||Oligocene (Tertiary)
||Deeply weathered, brecciated basalts
||500 metres, forms rugged terrain

|-
!colspan="4"| Sedimentary - Miocene (Tertiary) to Recent
|-
|Alwero Formation (largely consolidated) and associated unconsolidated sediments
||Miocene (Tertiary) to Recent
||
#Holocene alluvial sediments
#:Alluvial sediments composed of diatomites, red beds, fluvial materials and paleosols. These were probably developed during the Holocene climate fluctuations. Up to 400 metres thick.
#Quaternary alluvio-lacustrine sediments
#:Quaternary to recent alluvial sediments, lacustrine sediments, river terraces, volcanoclastics, colluvial and talus slopes, fluviatile and deltaic sediments, elluvials and soils. These localised deposits are present in central Ethiopia, southern and north western Ethiopia. Up to 500 metres thick.
#Pliocene (Tertiary) Alwero Formation
#: Sandstones
||1 km?. The Basin forms part of the Blue Nile rift in South Sudan and extends toward the west
|-
!colspan="4"| Sedimentary - Eocene
|-
|Auradu and Taleh formations - carbonate and evaporite rocks
||Eocene (Tertiary)
||Interbedded limestone, evaporite (anhydrite, gypsum) and shale
||500 metres; karst features observed
|-
!colspan="4"| Sedimentary - Upper Cretaceous
|-
|Jessoma Sandstone
||Upper Cretaceous
||Detrital, poorly cemented sandstone
||500 metres; poor surface drainage and plain forming- extends south up to Mogadishu in Somalia
|-
!colspan="4"| Sedimentary - Lower Cretaceous
|-
|Korahe Formation
||Lower Cretaceous
||Marine deposits; interbedded gypsum, shale, anhydrite, dolomite, limestone and sandstone
||Not known
|-
!colspan="4"| Sedimentary - Jurassic
|-
|Gabredarre, Hamanile, Urandab and Antalo formations - limestones
||Jurassic
||Dominantly limestone (75%) with some shale, marl and gypsum intercalations

The '''Gabredarre Formation''' includes oolitic limestones, marls and some gypsum. It is horizontally bedded and characterised by karst features, including solitary caves such as the famous Sofomar caves. The limestones of the Sofomar caves region have the highest degree of karstification of Ethiopia's carbonate rocks. The Gabredarre Formation has limestone cliffs that are moderately jointed and have intercalations of sand, marl and gypsum beds. The Gabredarre Formation grades down to the underlying Urandab Formation, which is the equivalent of the Antalo Limestone.

The '''Hamanile Formation''' consists of organogenic and oolitic limestones with shale and sandstone. The limestones are well jointed. The Haminile limestone plateau occurs on the Dolo to Negele Borena road around Bidre and consists of a marly, fractured, thinly (~1m) bedded limestone. Around Negele Borena the Hamanile limestone formation can be classified into at least five sub-units characterized by variable lithologies and intercalations. The succession is thinnest in the area of Negele town. The maximum thickness is about 700 m in the area of Filtu.
||1000 metres
|-
|Adigrat Sandstone
||Jurassic
||Highly cemented sandstone. The top part has been altered by heating from Cenozoic volcanism.
||700 metres
|-
!colspan="4"| Precambrian Mobile/Orogenic belt
|-
|Precambrian: Medium-High grade Mozambique belt in south and west Ethiopia
||Proterozoic
||Paleoproterozoic metasediments and gneiss and pre- and syn-tectonic granites. Generally high grade metamorphic rocks are interbedded with low grade metamorphic rocks
||This part of the basement in Ethiopia, unlike the basement in much of central Africa, has undergone multiple episodes of deformation and orogenesis.
|-
|Precambrian: Low grade Arabian Nubian Shield in Northern Ethiopia
||Proterozoic
||A transition zone between low grade volcano sedimentary succession and mafic ultramafic complexes of the Arabian Nubian Shield. The key lithologies are metavolcano sedimentary rocks and post-tectonic granite intrusive igneous rocks.
||
|-
|}

==Hydrogeology==

The most important aquifers in Ethiopia are formed by '''unconsolidated Quaternary sediments'''; '''Tertiary-Quaternary volcanic rocks'''; and '''Mesozoic consolidated sedimentary rocks'''. Basement aquifers are also important locally. A summary of these aquifers and their physical and chemical characteristics is in the tables below. More detailed information is available in the references listed below each table: many of these are available through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].

The hydrogeology map on this page shows a simplified version of the type and productivity of the main aquifers at a national scale (see the [[Africa Groundwater Atlas Hydrogeology Maps | hydrogeology Map]] resource page for more details).

[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Ethiopia geology and hydrogeology map'''].

Other hydrogeological maps from different sources have been produced and are available in different formats. Some can be viewed on the [http://www.bgr.de/app/fishy/whymis/index.php?&type=country&id=ETH WHYMAP] website.

[[File:Ethiopia Hydrogeology3.png | center | thumb| 500px| Hydrogeology of Ethiopia at 1:5million scale. For more information on how the map was developed see the [[Africa Groundwater Atlas Hydrogeology Maps | hydrogeology map]] resource page. [https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html Download a GIS shapefile of the Ethiopia geology and hydrogeology map].]]

====Unconsolidated====
<div id="Unconsolidated: Quaternary"></div>

{| class = "wikitable"
|Named Aquifers||Aquifer Productivity||General Description||Water quality
|-
|Alluvial sediments
||Afar Region - High Productivity. Northern Ethiopia - Low Productivity.
||Afar Region: alluvial deposits in floodplains have moderate to high permeability, with measured transmissivity from 1-500 m²/day and yields of up to 20 l/s. These aquifers can be unconfined and confined; they vary in thickness from 0 - 400 metres; water table depth is typically in the range 1 to 60 metres; typical borehole depth is 100 m; salinity is very variable.

In the Holocene alluvial aquifer borehole yields of 0.1 to 1 l/s have been recorded. Water levels are usually less than 5 m below ground surface.

Northern Ethiopia: alluvial sediments overlying basement rocks can store appreciable volumes of water and are characterised by high permeability and high water infiltration capacity. They are typically shallow and have limited lateral extent, and form perched aquifers. Springs and hand-dug wells are common, with recorded yields ranging between 0.05 l/s and 0.17 l/s.
||Variable salinity
|-
|Alluvio-lacustrine sediments
||Variable productivity, but can be highly productive in places
||These sediments have highly variable permeability. Fine sand deposits have the highest permeability, with some boreholes providing more than 10 l/s with minimal drawdown. Transmissivities range up to 700 m²/day and specific yields are of the order of 3.2 l/s/m. In several places higher transmissivities have been noted. For example, a 150 m deep borehole in alluvio-lacustrine deposits at the foot of the southern plateau has a transmissivity of 3012 m²/day. These aquifers can be both unconfined and confined; they vary in thickness from 0 to 400 metres; water table depth is typically in the range 1 to 60 metres; and the typical borehole depth is 100 m.

Fine-grained sands interbedded with massive volcanic tuffs and fine ash are known to have low productivity in many places (e.g. in the central Ethiopian Rift). In the eastern part of the country the total thickness of these sediments can reach about 300 m. In most of the outcrops, they consist of conglomerates, sandstone and mudstone, which are gypsiferous and locally bear saline groundwater.
||Variable salinity
|-
|Quaternary Alluvial Aquifers within Lake Tana basin
||Moderate to High Productivity
||These occur dominantly in the eastern part of the basin following the lower Rib and lower margin of Gumera and Fogera plain (East of Lake Tana). They also cover a significant area of the north part of the basin at the lower part of the Megech and Western shore of Lake Tana. However, the distribution of alluvial sediments is limited compared to the volcanic aquifers. The deposits vary in thickness from 1 to 400m. The aquifers can be unconfined or confined. Water table depth is typically in the range 1 to 60 metres, and typical borehole depth is 100 m.

The productivity of this aquifer is controlled by the intergranular permeability of the unconsolidated gravels, sand and clay. They are typically high productivity aquifers, with boreholes up to 60 m depth recorded as yielding more than 6 l/s.

The previous investigation aided with drilling on the lake floor shows the occurrence of indicates stiff clay up to 80 m depth.
||Variable salinity
|-
|Wadi bed aquifers
||Moderate to High Productivity
||Although localised, these intergranular aquifers have significant groundwater potential in water scarce arid and desert settings. Wadi bed length exceeds 30 000 km across Ethiopia, and total groundwater storage in these aquifers could be as much as 3 billion cubic metres. The most important wadi aquifers, which support the livelihoods of millions of people living a pastoral lifestyle, include those in Borena, Lower Omo, Ogaden, the Western Lowlands bordering Sudan, and in the Afar depression. The most productive wadi bed aquifers are those dominated by sandy and gravelly sediments with a low proportion of clay.

One of the highest yielding recorded boreholes abstracting from a wadi bed aquifer is the El-Gof borehole, which taps an intergranular sand and gravel aquifer, overlain by lacustrine sediments, and has a yield of 5 l/s. Other boreholes have recorded discharges of 0.5 l/s to 8 l/s.

An important source of groundwater in areas with little surface water
||Variable salinity
|-
|Talus slope, landslide bodies, alluvial terraces
||Moderate Productivity
||These deposits form small outcrops 0.5 to 2 km² in area. Permeability is enhanced in areas where the material is loosely packed. Groundwater from mountain areas flows towards the talus slope and landslide deposits, from where springs commonly emerge. Typical spring yields are 1 to 2 l/s. These aquifers with readily available groundwater discharges support several villages in areas of relatively gentle slopes and good soil development. Recharged from groundwater flowing from higher elevation.
||Variable salinity
|}

'''Key references for Quaternary unconsolidated aquifers of Ethiopia''' are Alemneh (1989); Chernet (1993) and Hadwen et al. (1973) (for more details see [[Hydrogeology of Ethiopia#Hydrogeology: key references | Key Hydrogeology References]]).

====Igneous - Volcanic====
{| class = "wikitable"
|Named Aquifers||Aquifer Productivity||General Description||Water quality
|-

|Rift volcanics
||Moderate Productivity
||Borehole yields generally from 1 to 5 l/s. In some conditions the aquifer is confined, leading to artesian conditions. Both direct rainfall and indirect (eg from river beds) recharge is common.
||High fluoride and salinity, often exceeding WHO limits.
|-
|Quaternary plateau basalts
||High Productivity
||The most extensive occurrence is in the Lake Tana Basin, where these form a highly productive, fractured aquifer, with borehole yields reaching 20 l/s (there are other records of borehole yields of between 5 and 100 l/s), and groundwater discharge to rivers and springs. Elsewhere in Ethiopia the Quaternary volcanics are highly productive but have dual fracture-intergranular porosity. Direct and indirect recharge occurs.
||Good water quality: generally bicarbonate type, low salinity, low fluoride.
|-
|Shield volcanics
||
||This aquifer can be up to 500 m thick. Groundwater discharge occurs through springs, which are common at the foot of the shield areas. The intercalation of volcanic ash with basalt forms a dual porosity and permeability groundwater system: groundwater storage is focussed in ash layers, while groundwater flow is focussed through fractures in the basalt layers. Shield areas dominated by acid volcanic rocks show lower groundwater potential (e.g. in the Bale Massif). The aquifer is typically unconfined to semi confined. The depth to water ranges from 5 to 60 m, and borehole depths are typically 60 to 150 metres. Recharge occurs through fractures in highland areas.
||Good water quality: generally bicarbonate type, low salinity, low fluoride.
|-
|Upper basalt aquifer (Aiba, Alaji and Termaber formations)
||High Productivity
||This aquifer forms the most productive of the volcanic aquifers in Ethiopia. It is typically unconfined to semi-confined and often artesian. Groundwater discharge occurs to wetlands and to springs on cliffs. The aquifer thickness ranges from 50 to 1000 m. The depth to water table varies from 0 to 250 metres. Borehole depths are typically from 100 to 150 m. Borehole yields are generally up to 20 l/s.

The Aiba Formation has dual porosity, with groundwater occurring in joints, fractures and scoriaceous layers. Deep boreholes show the presence of narrow but extensive fracture zones with high permeability and low storage. Transmissivity varies between 0.5 and 1400 m²/day. Borehole yields range from 5 to 150 l/s.

Pumping test analysis and well logs from the Termaber Formation show that it is dominated by fracture flow. Recharge occurs vertically through the soil zone and fractures in the rocks.
||Good water quality: generally bicarbonate type, low salinity, low fluoride.
|-
|Lower basalt aquifer (Ashangie Formation)
||Low to High Productivity
||These rocks are characterised by rugged topography with dissected and irregular morphology. The rocks are deformed, and in their northern section dip at up to 40°. They are thinly bedded, and in several areas are brecciated. Field evidence shows that the brecciated parts are characterized by lower permeability. The rocks are typically deeply weathered, when they are reddish in colour, but generally have low permeability. Both primary (vesicle) porosity and secondary (fracture) porosity have been modified and reduced by secondary mineralisation (e.g. by calcite, zeolite and silica).

In more detail, the Ashangie Formation can be divided into three zones:

1) an upper layer, with gentle topographic slopes. Mostly scoriaceous, with several thin beds of clay soils. Recharge occurs vertically through this layer to the underlying layers. Springs are rare, and most groundwater discharge occurs as diffuse seepage on slopes, often contributing to landslides.

2) a thinner middle, more resistant layer, which often forms cliffs. When exposed at the ground surface by erosion, this can form locally extensive plateau areas, such as around the Upper Tekeze plains, Lalibela and the Belesa plain. Typically has higher groundwater productivity.

3) a lower layer, also with gentle slope. Mostly scoriaceous, with several thin beds of clay soils. Often contains cross-cutting dykes which are conduits for groundwater convergence and discharge.

The aquifer thickness varies up to 500 m. The rugged topography means that the aquifer is not laterally extensive. Depressions in the rugged terrain are areas of groundwater discharge.

The aquifer is usually unconfined to semi-confined. Typical borehole yields are between 0.5 and 20 l/s. Transmissivity ranges between 0.5 and 85 m²/day. The water table depth is typically between 100 and 200 m, and borehole depths are typically 150 to 200 m.

The contact between this unit and the upper basalt above is characterised by spring discharge.
||Good water quality: generally bicarbonate type, low salinity, low fluoride.
|}

'''Key references for volcanic aquifers of Ethiopia''' are Kebede (2013) and Ayenew et al. (for more details see [[Hydrogeology of Ethiopia#Hydrogeology: key references | Key Hydrogeology References]]).

====Mesozoic Consolidated Sedimentary Aquifers with Fracture and Intergranular Flow====

Notable hydrogeologic and geologic features of Mesozoic sedimentary rocks of Ethiopia are:

- Uplifting and formation of tabular plateaus;

- deep incision by river gorges;

- absence of or limited karstification in carbonate rocks;

- absence of regional folding and flexures at the margins of the units; and

- extensive cover by younger volcanic rocks.

These features contrast with typical sedimentary basins elsewhere in Northern and Eastern Africa. In contrast to the sedimentary basin aquifers of northern and Sahel Africa, structural traps (such as synclines formed by compressional deformation) are uncommon, leaving little room for large volume groundwater storage.

{| class = "wikitable"
|Named Aquifers||Aquifer Productivity||General Description||Water quality
|-
|Hamanile, Gabredarre and Antalo formations (Jurassic limestones)
||High Productivity
|| The '''Gabredarre Formation''' is characterised by karst features, including caves. The limestones of the Sofomar caves region have the highest degree of karstification of Ethiopia's carbonate rocks. The aquifer has moderate permeability and productivity.

The '''Hamanile Formation''' limestones are well jointed with moderate to high permeability. Evidence from boreholes in highland and midlands areas, where the aquifer crops out, shows that groundwater levels can be very deep: for example, more than 200 m below ground level between Filtu and Negele. Where the water table is shallower, the Hamanile limestones form relatively productive aquifers.

In general, these aquifers are typically 500 to 1000 m thick, and are unconfined to semi-confined. The water table is usually 200 to 400 m deep; typical borehole depth is 300 m.

In high rainfall highlands, recharge could reach 200 mm/yr. In arid regions it varies between 10 mm/yr and 50 mm/yr.
||Good quality water generally. However, high concentrations of dissolved salts, including sodium, chloride and/or sulphate, occur due to reaction with abundant minerals in evaporite beds, and salinity can reach 3 mg/l.
|-
|Adigrat Formation (Jurassic sandstone)
||Moderate Productivity
||The highly cemented '''Adigrat Formation''' has low primary porosity, and the top part has been altered by heating by Cenozoic volcanism. Fracturing has created secondary porosity and permeability. The emergence of springs at the contact of the Adigrat sandstone and the overlying volcanic rocks is indicative of the low permeability of the Adigrat Formation.

This aquifer is typically 200 to 1000 m thick and is unconfined to semi-confined. The water table is usually 200 to 400 m deep; typical borehole depth is 300 m.

In highlands areas with high rainfall, recharge could reach 200 mm/yr. In arid regions it varies between 10 mm/yr and 50 mm/yr.
||Very good quality water
|}

'''Key references for Mesozoic sedimentary aquifers of Ethiopia''' are BSEE (1973), Chernet (1993), Hadwen et al. (1973), Haile et al (1996) and Kebede (2013) (for more details see [[Hydrogeology of Ethiopia#Hydrogeology: key references | Key Hydrogeology References]]).

====Precambrian Basement====
{| class = "wikitable"
|Named Aquifers||Aquifer Productivity||General Description||Water quality
|-
|Precambrian basement aquifers of Southern Ethiopia and Northern Ethiopia; Crystalline Basement aquifers of Western Ethiopia
||Very Low to Low Productivity.
||'''Basement aquifers in general'''

The productivity of basement aquifers in Ethiopia largely depends of the development of regolith (weathered rock) amd the density of fractures. In turn, these are partly controlled by the type or grade of metamorphic rock that forms the basement. Less important controls on groundwater occurrence are the sustainability of recharge; and topography. Groundwater in the basement aquifers occurs in shallow regolith (weathered rock) basins.

Borehole yields from the most productive boreholes in basement aquifers are generally less than 0.1 l/s. Spring discharges in the basement complex are of the order of 1 l/s. Generally, basement aquifers in western and south-central parts of Ethiopia are productive, and the lowest productivity basement aquifers are located in northern Ethiopia and the Borena lowlands (near the southern border).

The basement aquifers are unconfined. Aquifer (regolith) thickness varies from 0 to 60 m (thinner in northern Ethiopia and thicker in western Ethiopia - see below). The deepest known borehole struck water at 100 m. The water table is typically 2 to 60 m deep. Boreholes tend to be 60 to 120 m deep.

;Regional details:
:'''Northern Ethiopia''': the basement rocks of Northern Ethiopia have low groundwater potential. Groundwater occurs generally in fractures in the upper few metres of the unweathered rocks; in very thin regolith layers; and in patches of overlying alluvial sediments in river valleys (see the [[Hydrogeology of Ethiopia#Unconsolidated | Unconsolidated]] section for further information).
:'''Southern Ethiopia''': groundwater in the basement rocks is stored in, and transmitted through, both regolith layers and fractures. There is variable fracturing and regolith development. Borehole yields range from 0.13 to 0.33 l/s.
:'''Western Ethiopia''': the crystalline basement aquifers of Western Ethiopia have better groundwater storage than in other areas. This higher groundwater potential is related to high rainfall that supports high recharge; to a relatively thick regolith which favours groundwater storage; and to rugged undulating topography which favours accumulation of weathering products in depressions and flat plains allowing groundwater storage and circulation. The average borehole yield is 5 l/s (Bako & Abakoran). The hydraulic conductivity of this aquifer varies from 0.12 m/day to 2.3 m/day.

Recharge varies from 10 to 250 mm/yr depending on rainfall regime
||Good quality
|}

'''The key reference for basement aquifers of Ethiopia''' is Kebede (2013) (for more details see [[Hydrogeology of Ethiopia#Hydrogeology: key references | Key Hydrogeology References]]).

===Recharge===

Recharge over Ethiopia is extremely variable. It varies from nearly 0 to 300 mm/yr. Nearly 60% of aquifers receive indirect recharge from floods, mountain runoff, as well as fast recharge from high rainfall events. Diffuse recharge is limited to the plateau region which accounts for around 30% of the country.

The geological uplift in the Cenozoic which led to erosion and dissection of the aquifers into smaller size units, has resulted in generally low storage compared to large sedimentary basins elsewhere in Africa. The storage to recharge ratio is around 28 years (Kebede, 2013).

===Groundwater Quality===

Groundwater quality is highly variable across Ethiopia, from fresh waters in many of the springs flowing from basement aquifers, to more saline waters in volcanic aquifers in parts of the Rift Valley and sedimentary aquifers of the plains.

The key natural groundwater quality issues are:

;'''Fluoride'''.

Fluoride has long been a recognised health concern in Ethiopia. Concentrations of fluoride in groundwater that are higher than the WHO guideline value of 1.5 mg/l have been found across Ethiopia, but are concentrated in the Rift Valley, linked to the volcanic geology. Groundwater fluoride values of greater than 10 mg/l have been found in some areas ([http://nora.nerc.ac.uk/id/eprint/516312/1/Ethiopia.pdf Smedley 2001]). As a result of the long-term use of high-fluoride drinking water, both dental and skeletal fluorosis are known to occur in populations from the Rift Valley. However, more research is needed on the links between geology, hydrogeology, fluoride concentrations and fluorosis in order to target interventions.

;'''Salinity'''.

High values of total dissolved salts in volcanic aquifers in the Rift Valley are linked to the influence of geothermal waters. Increased salinity in many groundwaters in sedimentary aquifers in the south, southeast and northeast of the country, is linked to the dissolution of evaporite minerals.

Key references for more information on groundwater quality in Ethiopia are:

British Geological Survey/WaterAid. 2001. [http://www.wateraid.org/~/media/Publications/groundwater-quality-information-ethiopia.pdf Groundwater Quality: Ethiopia]. Leaflet.

===Groundwater Status===

;Groundwater quantity
Annual renewable groundwater resources are estimated at around 36,000 million cubic metres (36 billion cubic metres) , with estimates of total groundwater storage varying from 1,000 to 10,000 billion m³.

;Groundwater guality:
An estimated 30% of groundwater storage is not available for direct use because of high salinity and/or high fluoride.

;Groundwater-Surface Water Interaction:
- There are a number of groundwater dependent surface waters, including wetlands and lakes.
- Wetlands are increasingly threatened by deepening, widening and propagating gullies as well as by infestation by invasive weeds

;Groundwater Dependent Ecosystems
There is low recognition at government level of the fact that wetlands are groundwater dependent.

==Groundwater use and management==

=== Groundwater use===

Some 80% of the total national water supply comes from groundwater.

Kebede (2013) gives national estimates of groundwater abstraction volumes. Groundwater provides most of the water for domestic supply (90%) and industrial use (95%).

To date only a very small proportion of irrigation demand (<1%) comes from groundwater, including small well irrigation by smallholder farmers, but some larger commercial irrigation schemes are pioneering the use of groundwater. Groundwater use for livestock watering is unknown. More hydrogeological research may help increase the use of groundwater for irrigation, for example in proving the existence of a large enough resource that can be sustainably abstracted.

Groundwater sources in Ethiopia consist of:
*Boreholes
*Hand dug wells
*Improved cold springs
*River bed excavations/pits
*Haffirs
*Traditional Ella wells (very large diameter wells)
*Bircados

=== Groundwater management===

There are currently no regional or national groundwater level or quality monitoring programmes, and relatively little formal registration of boreholes and other water abstraction points.

The key groundwater institutions, and their roles, are:

*Ministry of Water Irrigation and Energy- Regulatory, policy, financing, planning, maintenance of information base

*Geological Survey of Ethiopia- Exploration and Mapping

*Ministry of Forestry and Environment: Reviewing possible impacts of national investments on groundwater quality and quantity; Selected strategic environmental assessments – linked to groundwater management plans

*Agricultural Transformation Agency- Shallow groundwater mapping and management policy

*Regional Water Bureaus- Regulatory, policy, financing and planning

*Water Works Enterprises- Study, Design, Supervision and Development

*Regional Ministry of Forestry and Environment: Licensing and Impact assessment of investment on groundwater

*River Basin Organizations: Allocation and supplies

*Water User Associations: Local regulation and allocation; formal and informal

*Drillers' Association

*Technical and vocational Schools (TVETs): training human power in groundwater development , low skill

There is a limited legal framework for groundwater management, but the regulations are not systematically implemented. No regulatory provision exists to protect vulnerable areas. The report “Groundwater Management framework document (MWR, 2010)” includes the following regulatory provisions:

*No person shall be engaged in the drilling or rehabilitating of water wells without a permit duly issued by the Ministry or his designee.
*Any person who wants to have water well drilled shall first acquire a permit to do so from the Ministry or his designee before entering a contract for this purpose with a water well drilling or rehabilitating contractor. Applications made to have a water well drilling or rehabilitating contractor. Applications made to have water well drilled must be accompanied with the design and specifications of such well.
*All water well drillers and rehabilitators shall, before entering in to a contract to drill water well, first ensure that the Ministry or his designee has approved that such well be drilled.
*All persons who want to have a water well drilled or rehabilitated shall, before entering in to a contract to have such water well drilled or rehabilitated, first ensure that the driller or rehabilitator has a permit to undertake the drilling or rehabilitating or water wells.
*A well driller or rehabilitator shall, within three months of completing a well drilling or rehabilitation, submit to the Ministry or his designee a technical report – that includes information about the drilling, construction and rehabilitation process, the geological and electrical log, yield tests, laboratory tests, problems encountered during drilling, construction and rehabilitation, pump installed.

Informal local water user organisations exist for most small-scale traditional water schemes, including groundwater, that operate on more than an individual/household level, and typically do not have legal recognition or support. For formal and most modern schemes, there is usually a formal statutory water user association or irrigation cooperative.

=== Groundwater data===

=== Transboundary aquifers===

The major transboundary aquifers in Ethiopia are:

*The unconsolidated sedimentary aquifers of Gambella (Upper Blue Nile) and Alwero Sandstone: Ethiopia and South Sudan
*The Bulal Basalt aquifer: Ethiopia and Kenya
*The Hanle Graben aquifer: Djibouti and Ethiopia
*The Sedimentary Basin of Ogaden: Ethiopia and Somalia

No management system exists specifically pertaining to transboundary aquifers. Conflict over water sources in general is common among pastoralists in the border region of Ethiopia and Kenya.

==Groundwater Projects==

Information on particular groundwater projects in Ethiopia, including links to project results and outputs, can be found on the [[Ethiopia Groundwater Projects | Ethiopia groundwater projects]] page.

==References==

Many of the references below, and others relating to the hydrogeology of Ethiopia, can be accessed through the [https://www.bgs.ac.uk/africagroundwateratlas/atlas.cfc?method=listResults&title_search=&titleboolean=AND&author_search=&category=&child_category=&country=ET African Groundwater Literature Archive].

===Geology: key references===

Beyth M. 1972. The Geology of Central Western Tigre, Ethiopia. University of Bonn, p. 155.

EGS. 1996. Geological map of Ethiopia at 1:2000000 scale. Ethiopian Geological Survey, Addis Ababa, Ethiopia

Davidson A. 1983. The Omo River Project. Reconnaissance geology and geochemistry of parts of Illubabor, Kefa, Gemu Gofa and Sidamo, Ethiopia. Ethiopian Institute of Geological Surveys Bull 2, 89 pp.

Kazmin V, Shiferaw A and Balcha T. 1978. The Ethiopian basement: stratigraphy and possible manner of evolution. GeologischeRundschau 67, 531–548.

Kieffer B, Arndt N, Lapierre H et al. 2004. Flood and Shield Basalts from Ethiopia: Magmas from the African Superswell. J of Petrology 45:793-834

Le Turdu C, Tiercelin JJ, Gibert E et al. 1999. The Ziway–Shala lake basin system, Main Ethiopian Rift: influence of volcanism, tectonics, and climatic forcing on basin formation and sedimentation. Palaeogeography, Palaeclimatology and Palaeoecology 150: 135–177.

Mohr P. 1973. Crustal deformation rate and the evolution of the Ethiopian rift. In: Tarling DH, Runcorn SK (eds) Implications of continental drift to the earth sciences. Academic Press, London, pp 767–776

Mohr P. 1983. Ethiopian Flood Basalt Province. Nature 303:577- 584.

Mohr P and Zanettin B. 1988. The Ethiopian flood basalt province. In: Macdougall, J. D. (ed.) Continental Flood Basalts. Dordrecht: Kluwer Academic, pp. 63---110.

Rochette P, Tamrat E, Feraud G et al. 1998. Magnetostratigraphy and timing of the Oligocene Ethiopian Traps. Earth and Planet.Sci. Lett, 164: 497-510.

Taddesse T, Hoshino M, Sawada Y. 1999. Geochemistry of low-grade metavolcanic rocks from the Pan-African of the Axum area, northern Ethiopia. Precambrian Research 99: 101–124

USBR. 1964. Land and water resources of the Blue Nile basin, Ethiopia. United States Bureau of Reclamation, Main report, Washington.

WoldeGabriel G, Walter RC, Aronson JL. 1992. Geochronology and distribution of silicic volcanic rocks of Plio-Pleistocene age from the central sector of the Main Ethiopian Rift. Quat. Int. 13–14, 69–76.

Zanettin B, Justin-Visentin E. 1974. The volcanic succession in central Ethiopia, the volcanics of the western Afar and Ethiopian Rift margins. Univ. Padova Inst. Geol. Mineral. Mem. 31, 1–19.

===Hydrogeology: key references===

Alemneh S. 1989. Hydrogeology of Yabello sheet (NB37-14). Ethiopian Geological Survey report number 307. Addis Ababa, 40pp.

Awulachew S. 2010. [https://agriknowledge.org/downloads/j38606956 Irrigation potential in Ethiopia: Constraints and opportunities for enhancing the system]. IWMI.

Ayenew T, Demli M and Wohnlich S. DATE. Occurrence of groundwater in Ethiopian volcanic terrain. Journal of Africa Earth Sciences, 52 (3), 97–113.

BCEOM. 1999. Abay River Basin integrated master plan, main report, Ministry of Water Resources, Addis Ababa.

Belete Y, Alemirew D, Mekonen A et al. 2004. Explanatory notes to the hydrogeological and hydrochemical maps of the Asosa-Kurmuk Area (NC36-7 West of Assosa and NC36-8 Assosa sheets). Geological Survey of Ethiopia, Addis Ababa, 120 pp.

BSEE. 1973. The caves of Ethiopia, The 1972 British SpeleologiclaExpediation to Ethiopia. Transaction Cave Research Group of Great
Britain, 15:107-168

Chernet T. 1982. Hydrogeologic map of the lakes region (with memo) Ethiopian Institute of Geological Survey (now Ethiopian Geological Survey), Addis Ababa Ethiopia.

Chernet T. 1993. Hydrogeology of Ethiopia and water resources development Ethiopian Institute of Geological Surveys, Addis Ababa, 222pp.

Federal Democratic Republic of Ethiopia Ministry of Water Resources and GW-MATE. 2011. [http://metameta.nl/wp-content/uploads/2012/10/2011_03_08_eth_frwrk_FINALSF.pdf Ethiopia: Strategic Framework for Managed Groundwater Development].

Gasse F. 1977. Evolution of Lake Abhe (Ethiopia and TFAI), from 70,000 BP. Nature (London) 265 (5589), 42– 45.

Gasse F and Street FA. 1978. Late Quaternary lake level fluctuations and environments of the northern Rift Valley and Afar region (Ethiopia and Djibouti). Paleogeogr. Paleoclimatol. Paeoecolo. 24, 279-221

Gebru TA and Tesfahunegn GB. 2019. [https://doi.org/10.1007/s10040-018-1845-8 Chloride mass balance for estimation of groundwater recharge in a semi-arid catchment of northern Ethiopia]. Hydrogeology Journal 27 (1), 363–378. doi: 10.1007/s10040-018-1845-8.

Hadwen P. 1975. Boreholes in Ethiopia. Geological Survey of Ethiopia, Unpublished report number 29, Hydrogeology Division, Technical Memorandum 9, Addis Ababa, 22pp.

Hadwen P, Aytenfisu M and Mengesha G. 1973. Groundwater in the Ogaden. Geological Survey of Ethiopia, report number 880-551-14. 59pp.

Haile A, Kebede G and Lemessa G. 1996. Reconnaissance Hydrogeological and Engineering Geological Survey of Bikilal, Achebo and Dilbi Areas. Ethiopian Institute of Geological Survey, Report Number 880-351-06., Addis Ababa, 9pp.

Hailemeskel M. 1987. Hydrogeology of South Afar and Adjacent areas, Ethiopia. Supported by interpretation of LANDSAT imagery. Unpublished MSc thesis. International Institute for Aerial survey and Earth Sciences (ITC), Enschede, the Netherlands.

Halcrow. 2008. Rift Valley Lakes Basin Integrated Resources Development Master Plan Study Project. Main Report. Halcrow Group Limited and Generation Integrated Rural Development (GIRD) Consultants, Ministry of Water and Energy, Addis Ababa

Kebede S, Travi Y, Alemayehu T and Ayenew T. 2005. Groundwater Recharge, Circulation and Geochemical Evolution in the Source Region of the Blue Nile River, Ethiopia. Appl. Geochem. 20, 1658

Kebede S. 2013. Groundwater in Ethiopia: Features, vital numbers and opportunities. Springer, Berlin. ISBN 978 3 642 30390 6. Available to purchase at http://www.springer.com/gp/book/9783642303906

Ministry of Water and Energy. 2013. [http://metameta.nl/wp-content/uploads/2013/03/Task_Force_Report_Supplement.pdf Supplement to Task Force Report on Aquifer Management for Addis Abeba and Vicinity]. Ethiopia: Practical Framework for Managed Groundwater Development in the Greater Addis Ababa Area

MWR. 2007. Evaluation of water resources of the Ada’a and Becho plains groundwater basin for irrigation development project, Volume III: Groundwater Evaluation Report, Water Works Design and Supervision Enterprise, Addis Ababa, 188pp.

MWR. 2010. Ethiopia: Strategic Framework for Managed Groundwater Development, Report prepared by World bank - GWMate project, 77pp, Addis Ababa

Ralph M Parsons Company. 1968. Groundwater condition at Dallol, Ethiopia, Geological Survey of Ethiopia report number 880-201-01, Addis Ababa, 29pp.

Sima J. 1987. Hydrogeology and Hydrochemistry of the Bako and Ist’IfanosHayk’ areas (NB 37-9 and NB37-13), Provision Military Government of Socialist Ethiopia, Ministry of Mines and Engergy, Ethiopian Institute of Geological Surveys. Note Number 271, Addis Ababa, 65pp.

Sima J. 2009. Water Resources Management and Environmental Protection Studies of the Jemma River Basin for Improved Food Security. AQUATEST ,Geologicka Prague, Czech Republic, 220 pp.

Smedley P. 2001. [http://nora.nerc.ac.uk/id/eprint/516312/1/Ethiopia.pdf Groundwater quality: Ethiopia]. British Geological Survey.

Spate Irrigation Network Foundation. 2015. [http://spate-irrigation.org/wp-content/uploads/2015/03/OP17_Flood-wells-Ethiopia_SF.pdf Status and potential of groundwater use in Ethiopian floodplains]. Practical Note Spate Irrigation 17.

Tadesse K. 1980. Hydrogeology of Borkena River Basin, Wollo Ethiopia. Unpublished MSC thesis, Addis Ababa University, 129pp.

USBR. 1964. Land and water resources of the Blue Nile basin, Ethiopia. United States Bureau of Reclamation, Main report, Washington.

WAPCOS. 1990. Preliminary Water Resources Development Master Plan for Ethiopia, Ministry of Water Resoruces, Addis Ababa.

WWDSE. 2009. Groundwater Resources of the Upper Tekeze Basin: Resource Description, Assessment and Model, Interim Report. Water Works Design and Supervision Enterprise, Addis Ababa, 74pp.

Zerai H and Sima J. 1986. Hydrogeology and hydrochemistry of the Dire Dawa area (Sheet NC 37 12). Provisional Military Government of Ethiopia, Ethiopian Institute of Geological Survey, Note number 276, Addis Ababa, 82pp.

Return to the index pages:
[[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]


[[Category:Hydrogeology by country|e]]
[[Category:Africa Groundwater Atlas]]

Ethiopia Groundwater Projects

2020-10-06T15:08:41Z

KirstyUpton:

[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> [[Hydrogeology of Ethiopia | Hydrogeology of Ethiopia]] >> Ethiopia Groundwater Projects

The following is a list of selected groundwater projects in Ethiopia.

Note: this is not a comprehensive list of groundwater projects: there are many more. If you have information on other significant groundwater projects in Ethiopia, please let us know and we will add them to these lists. Contact us on AfricaGWAtlas@bgs.ac.uk

:- The UPGro project [https://upgro.org/consortium/hidden-crisis2/ '''Hidden Crisis'''] investigated the multiple reasons for borehole hand pump failure in Ethiopia as well as in Malawi and Uganda.

:- the [https://www.usgs.gov/centers/nj-water/science/africa-groundwater-exploration-and-assessment-program?qt-science_center_objects=0#qt-science_center_objects '''Africa Groundwater Exploration and Assessment Program'''] is run by the [https://www.usgs.gov/ US Geological Survey] (USGS) and funded by [https://www.usaid.gov/ USAID]. The programme aims to build a good understanding of the potential for developing potable groundwater supply in Ethiopia and Kenya, and to build local capacity to plan and carry out the groundwater investigations and monitoring needed for good, sustainable groundwater resource development and management. One part of this project has been [https://www.globalwaters.org/GWS-Stories/developing-groundwater-maps-arid-regions-kenya-and-ethiopia developing groundwater maps for arid regions of Kenya and Ethiopia].

:- The [https://gw4e.acaciadata.com/home '''Groundwater mapping for climate resilient WASH in arid and semi-arid areas of Ethiopia'''] project (2018-2020) created harmonized geological maps, groundwater suitability maps and socio-economic maps on a scale of 1:250,000 for eight clusters in Ethiopia. 1:50,000 hydrogeological maps and 1:10,000 drilling maps were then prepared for target kebeles to dientify potential drilling sites. All documents, maps and data can be visualized and downloaded from a public webservice system, the [https://gw4e.acaciadata.com/home '''GW4E viewer'''].

Return to
[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> [[Hydrogeology of Ethiopia | Hydrogeology of Ethiopia]]


[[Category:Africa Groundwater Atlas]]

[[Category:Groundwater Projects]]

Hydrogeology of South Sudan

2019-09-23T15:59:14Z

KirstyUpton:

[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of South Sudan

[[File:CC-BY-SA_logo_88x31.png | frame | This work is licensed under a [https://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License]]]

Nilotic peoples have lived in the area of South Sudan since before the 10th century. Migrations of many ethnic groups into the region continued during the following centuries. In the late 19th century, Egypt claimed part of the region, establishing the province of Equatoria. By the end of the 19th century the region was under joint British-Egyptian control. The region of South Sudan, as part of Sudan, became independent in 1956. Two civil wars dominated the following decades: the first from 1955 to 1972, and the second from 1983 to 2005. A factor in both wars was the perceived marginalisation of the southern population by the northern-dominated government. The ethnic mix in South Sudan is dominated by Dinka, Nuer and other Nilotic peoples, who are traditionally Christian or animist, distinct from the dominantly Arab and Muslim identity of present day Sudan to the north. South Sudan was designated an autonomous region of Sudan in 1972, with an autonomous government after a peace agreement in 2005. A referendum led to the creation of the Republic of South Sudan as an independent country in 2011. Conflict has continued since independence, both internally and with Sudan, in part over disputed oil-rich land and conditions of use of oil transport infrastructure. A civil war began in 2013 and has caused widespread violence and deaths and the creation of millions of internally displaced people or refugees.

South Sudan’s economy and infrastructure are poorly developed, having suffered decades of civil war. Livelihood activities are dominated by agriculture, particularly traditional stock-raising. The country has significant mineral and oil resources. Oil is the main source of export income, but development of the industry has been complicated by disputes with Sudan, particularly as exports rely on pipelines and other infrastructure in Sudan. Timber is also exported.

South Sudan has relatively high seasonal rainfall, especially in the south, and a number of major rivers flow through the country, including the White Nile. However, water resources are unevenly distributed, water supply infrastructure is poorly developed and access to improved water supplies is low. Groundwater is the main source of drinking water for most of the population, but there has been relatively little investigation of groundwater resources in the country.

==Compilers==

'''Dr Kirsty Upton''' and '''Brighid Ó Dochartaigh''', British Geological Survey, UK

'''Dr Imogen Bellwood-Howard''', Institute of Development Studies, UK

Please cite this page as: Upton, Ó Dochartaigh and Bellwood-Howard, 2018.

Bibliographic reference: Upton K, Ó Dochartaigh BÉ and Bellwood-Howard, I. 2018. Africa Groundwater Atlas: Hydrogeology of South Sudan. British Geological Survey. Accessed [date you accessed the information]. http://earthwise.bgs.ac.uk/index.php/Hydrogeology_of_Souht_Sudan

==Terms and conditions==

The Africa Groundwater Atlas is hosted by the British Geological Survey (BGS) and includes information from third party sources. Your use of information provided by this website is at your own risk. If reproducing diagrams that include third party information, please cite both the Africa Groundwater Atlas and the third party sources. Please see the [[Africa Groundwater Atlas Terms of Use | Terms of use]] for more information.

==Geographical Setting==

[[File:South Sudan_Political.png | right | frame | South Sudan. Map developed from USGS GTOPOPO30; GADM global administrative areas; and UN Revision of World Urbanization Prospects. For more information on the map development and datasets see the [[Geography | geography resource page]].]]

===General===

{| class = "wikitable"
|-
|Capital city || Juba
|-
|Region || Eastern/Northern Africa
|-
|Border countries || Sudan, Ethiopia, Kenya, Uganda, the Democratic Republic of the Congo, the Central African Republic
|-
|Total surface area* || 644,330 km<sup>2</sup> (64,433,000 ha)
|-
|Total population (2015)* || 12,340,000
|-
|Rural population (2015)* ||10,055,000 (81%)
|-
|Urban population (2015)* ||2,285,000 (19%)
|-
|UN Human Development Index (HDI) [highest = 1] (2014)*|| 0.4667
|}

<nowiki>*</nowiki> Source: [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en FAO Aquastat]

===Climate===

[[File:South Sudan_ClimateZones.png | 375x365px |Koppen Geiger Climate Zones]][[File:South Sudan_ClimatePrecip.png | 375x365px |Average Annual Precipitation]][[File:South Sudan_ClimateTemp.png | 375x365px |Average Temperature]]

[[File:South Sudan_pre_Monthly.png| 255x124px| Average monthly precipitation for South Sudan showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File:South Sudan_tmp_Monthly.png| 255x124px| Average monthly temperature for South Sudan showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File:South Sudan_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File:South Sudan_pre_Mts.png|255x124px | Monthly precipitation (blue) over the period 2000-2012 compared with the long term monthly average (red)]]

More information on average rainfall and temperature for each of the climate zones in South Sudan can be seen at the [[Climate of South Sudan | South Sudan climate page]].

These maps and graphs were developed from the CRU TS 3.21 dataset produced by the Climatic Research Unit at the University of East Anglia, UK. For more information see the [[Climate | climate resource page]].

===Surface water===

{|
|-
|

| [[File:South Sudan_Hydrology.png | frame | Major surface water features of South Sudan. Map developed from World Wildlife Fund HydroSHEDS; Digital Chart of the World drainage; and FAO Inland Water Bodies. For more information on the map development and datasets see the [[Surface water | surface water resource page]].]]

|
|}

===Soil===
{|
|-
| [[File:South Sudan_soil.png | frame | Soil Map of South Sudan, from the European Commission Joint Research Centre: European Soil Portal. For more information on the map see the [[Soil | soil resource page]].]]

|
|}

===Land cover===
{|
|-
|

| [[File:SouthSudan_LandCover.png | frame | Land Cover Map of South Sudan, from the European Space Agency GlobCover 2.3, 2009. For more information on the map see the [[Land cover | land cover resource page]].]]

|

|}

===Water statistics===

{| class = "wikitable"
| || 2011||2012||2013||2014||2015
|-
|Rural population with access to safe drinking water (%) || || || || ||56.9
|-
|Urban population with access to safe drinking water (%) || || || || ||66.7
|-
|Population affected by water related disease ||No data || No data || No data || No data || No data
|-
|Total internal renewable water resources (cubic metres/inhabitant/year) || || || ||2,107 ||
|-
|Total exploitable water resources (Million cubic metres/year) ||No data || No data || No data || No data || No data
|-
|Freshwater withdrawal as % of total renewable water resources ||1.329 || || || ||
|-
|Total renewable groundwater (Million cubic metres/year) || || || ||4,000 ||
|-
|Exploitable: Regular renewable groundwater (Million cubic metres/year) ||No data || No data || No data || No data || No data
|-
|Groundwater produced internally (Million cubic metres/year) || || || ||4,000||
|-
|Fresh groundwater withdrawal (primary and secondary) (Million cubic metres/year) ||No data || No data || No data || No data || No data
|-
|Groundwater: entering the country (total) (Million cubic metres/year) ||No data || No data || No data || No data || No data
|-
|Groundwater: leaving the country to other countries (total) (Million cubic metres/year) ||No data || No data || No data || No data || No data
|-
|Industrial water withdrawal (all water sources) (Million cubic metres/year) ||225 || || || ||
|-
|Municipal water withdrawal (all water sources) (Million cubic metres/year) ||193 || || || ||
|-
|Agricultural water withdrawal (all water sources) (Million cubic metres/year) ||240 || || || ||
|-
|Irrigation water withdrawal (all water sources) <sup>1</sup> (Million cubic metres/year) ||No data || No data || No data || No data || No data
|-
|Irrigation water requirement (all water sources) <sup>1</sup> (Million cubic metres/year) ||No data || No data || No data || No data || No data
|-
|Area of permanent crops (ha) ||No data || No data || No data || No data || No data
|-
|Cultivated land (arable and permanent crops) (ha) || ||2,760,000 || || ||
|-
|Total area of country cultivated (%) || ||4.284 || || ||
|-
|Area equipped for irrigation by groundwater (ha) ||1,524 || || || ||
|-
|Area equipped for irrigation by mixed surface water and groundwater (ha) ||No data || No data || No data || No data || No data
|}

These statistics are sourced from [http://www.fao.org/nr/water/aquastat/main/index.stm FAO Aquastat]. They are the most recent available information in the Aquastat database. More information on the derivation and interpretation of these statistics can be seen on the FAO Aquastat website.

Further water and related statistics can be accessed at the [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en Aquastat Main Database].

<sup>1</sup> More information on [http://www.fao.org/nr/water/aquastat/water_use_agr/index.stm irrigation water use and requirement statistics]

==Geology==

The geology map shows a simplified overview of the geology at a national scale (see the [[Geology | Geology resource page]] for more details).

[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the South Sudan geology and hydrogeology map'''].

More information is available in the [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060049 UN report (1988)], and in other references listed below. Some of the information in the [[Hydrogeology of Sudan | Hydrogeology of Sudan]] page may also be useful.

[[File:SouthSudan_Geology3.png | center | thumb| 500px | Geology of South Sudan at 1:5 million scale. Based on map described by Persits et al. 2002/Furon and Lombard 1964. For more information on the map development and datasets see the [[Geology | geology resource page]]. [https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html Download a GIS shapefile of the South Sudan geology and hydrogeology map].]]

'''Summary'''

South Sudan’s geology ranges from Precambrian crystalline basement rocks to Quaternary unconsolidated alluvial deposits. Significant periods of erosion during the Paleozoic and Mesozoic removed the majority of sedimentary cover deposited on the crystalline basement during these times.

Tectonic movements of the Rift System during the Paleogene and Neogene Periods (middle to upper Tertiary) led to the formation of large structural basins across southern Sudan and South Sudan. These are generally north-west to south-east trending, perpendicular to the Central African Shear Zone in central Sudan.

The Muglad Basin is the main rift basin in South Sudan, covering an area of approximately 120,000 km2 across South Sudan and southern Sudan. This basin, along with others in the rift system, received thick fluvial and lacustral deposits during the Pliocene-Pleistocene (late Tertiary to early Quaternary Period). These deposits constitute the Umm Ruwaba Formation (see below). The Muglad Basin contains a number of hydrocarbon reserves which are exploited for export and domestic consumption.

Volcanic activity during the late Neogene and early Quaternary Periods produced the volcanic deposits that outcrop in the south-east of South Sudan.

{| class = "wikitable"
|+ Geological Environments
|Key Formations||Period||Lithology||Structure

|-
!colspan="4"|Unconsolidated sedimentary deposits
|-
| Nile alluvium, wadi fill and swamp deposits
||Quaternary
||These are widely deposited along the Nile River and its tributaries.

Ancient and recent terrace deposits consist of well-sorted silts and clays with occasional sandy strata and can be up to 60m thick.

Alluvial fill consists of medium to coarse, poorly-sorted sands with gravel and lenses of clay in places.

Clays and silts up to 30-50m thick can be found around smaller tributaries and in deltaic environments.
||

|-
| Um Ruwaba Formation
||Late Tertiary to Quaternary
||Unconsolidated superficial sediments (sands, gravels, clays) with little stratification.

Pebble layers can occur at the base where it is in contact with the basement.

The Umm Ruwaba contains lenticular sand and clay units which vary significantly vertically and horizontally.
|| Thickness varies depending on position within the basin; minimum thickness is around 50m at the edge of the basin; maximum thickness is around 1400m along the main axis of the basin.

The Umm Ruwaba is thought to overlie older Tertiary and Cretaceous deposits, which may reach a maximum thickness of around 10,000 m.

|-
!colspan="4"|Igneous Volcanic
|-
|
||Tertiary
||Basic volcanic rocks.
||

|-
!colspan="4"| Mesozoic Sedimentary Rocks - mainly Cretaceous
|-
|Nubian Sandstone Formation
||Upper Jurassic to Lower Cenozoic (mainly Cretaceous)
||The Nubian Sandstone extends from Sudan into northern South Sudan and comprises largely horizontal or gently dipping, well stratified sandstones with layers of conglomerate and siltstone (UN 1988). It is generally overlain by unconsolidated sediments of the Um Ruwaba Formation, but the thickness of these deposits varies spatially (see Um Ruwaba description above). It is possible that the exposed outcrop of Nubian Sandstone in the north west of the country is also overlain by unconsolidated deposits, but the thickness and extent of these is not well documented.

||Major faults are recognised in the Nubian Sandstone, sometimes displacing more than 2 km of sedimentary rocks.

|-
!colspan="4"| Precambrian Basement
|-
|
||Precambrian
|| Mainly undifferentiated basement with granitic intrusions, particularly in the north west.
||Rocks are heavily folded and faulted; NE-SW and NW-SE fractures are common.

|}

==Hydrogeology==

The hydrogeology map below shows a simplified overview of the type and productivity of the main aquifers at a national scale (see the [[Africa Groundwater Atlas Hydrogeology Maps | Hydrogeology Map]] resource page for more details).

[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the South Sudan geology and hydrogeology map'''].

More information on the hydrogeology of South Sudan is available in the report [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060049 United Nations (1988)], which covers South Sudan and Sudan (see also References section, below). Some of the information in the [[Hydrogeology of Sudan |Hydrogeology of Sudan]] page may also be useful.

[[File:SouthSudan_Hydrogeology3.png | center | thumb| 400px | Hydrogeology of South Sudan at 1:5 million scale. For more information on how the map was developed see the [[Africa Groundwater Atlas Hydrogeology Maps | Hydrogeology map]] resource page. [https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html Download a GIS shapefile of the South Sudan geology and hydrogeology map].]].

====Unconsolidated====
{| class = "wikitable"
|Aquifer Productivity||Named Aquifers and General Description||Water quantity issues||Water quality issues||Recharge
|-
|Low to High Productivity
|| These unconsolidated sedimentary deposits consist of alluvial sands, silts, gravels and clays. Aquifer properties are variable, depending largely on lithology, but where the alluvium is dominated by coarser grained deposits, transmissivity can be high. Aquifers are usually unconfined with a shallow water table (<15mbgl).

In the Sudd region groundwater levels are often above the land surface forming large swamp (wetland) areas.

Groundwater flow patterns usually follow surface water features.

Estimates of transmissivity and storage are given in the [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060049 UN report (1988)] of 200-1500 m2/d and 0.13-0.25, respectively.

Collapsing sands can be a significant problem for drilling in this formation, and boreholes can become heavily silted if not installed and constructed appropriately. See [[Case Study Drilling South Sudan | Drilling in South Sudan Case Study]] for further information.
||
||Water quality is usually good.
|| Aquifers receive direct recharge from rainfall during the wet season, however this can be restricted where thick clay-rich soils (vertisols – see map above) are present.

Aquifers may receive recharge from rivers during periods of high flow, but aquifers may discharge to rivers during the dry season.

Evaporation is high, particularly in the large swamp/wetland areas in the Sudd basin in the north.
|-
|Low to Moderate Productivity
|| The Umm Ruwaba Formation forms an unconsolidated aquifer that covers a large area, and is generally of low to moderate productivity. The properties of the aquifer vary depending largely on lithology, with lenticular sand and pebble horizons being the most productive.

The aquifer can be unconfined, or locally semi-confined where permeable layers occur below clay strata at depth (UN 1988).

There are few estimates of transmissivity and storage available for the Umm Ruwaba in South Sudan; estimates from basins in Sudan range from <50 m2/d to >800 m2/d, with well yields reported between 5 and 16 m3/hr (1.4-4.5 l/s); yields of 2.5-10 m3/hr (0.7-2.8 l/s) are reported for boreholes in the Bentiu area in northern South Sudan, which are drilled to depths of 100-220m, although higher yields may be possible in some boreholes (Groundwater Relief 2016);

Aquifer thickness may be several hundreds of metres but boreholes are typically drilled to depths of <250m.

Collapsing sands can be a significant problem for drilling in this formation, and boreholes can become heavily silted if not installed and constructed appropriately.

See [[Case Study Drilling South Sudan | Drilling in South Sudan Case Study]] for further information.
||The aquifer is used mostly for small domestic supplies and livestock watering (UN 1988).
|| Water quality is usually good, but high salinity can be an issue, particularly where hydraulic gradients are low and stagnation occurs.
||Recharge is dominantly from rainfall infiltration, and is relatively small.
|}

==== Consolidated Sedimentary - Intergranular Flow: Nubian Sandstone Aquifer====
{| class = "wikitable"
|Aquifer Productivity||Named Aquifers and General Description||Water quantity issues||Water quality issues||Recharge
|-
|Low to High Productivity
||The Nubian Sandstone Formation is a major regional aquifer (see the [[Hydrogeology of Sudan |Hydrogeology of Sudan]] page for more detail). In South Sudan it is largely overlain by unconsolidated deposits, which vary in thickness (see above). The outcrop mapped in the north west of the country may also be overlain by unconsolidated deposits, but the nature and thickness of these deposits is not known.
||
||
||
|}

====Basement====
{| class = "wikitable"
|Aquifer Productivity||Named Aquifers and General Description||Water quantity issues||Water quality issues||Recharge
|-
|Low Productivity
|| Groundwater occurs in fractures and/or in shallow weathered zones in Precambrian bedrock, where permeability has been increased. These aquifer zones are typically between 5 m and 20 m thick, but can be thicker – logs from boreholes drilled into granitic basement rocks close to Juba show a weathering profile up to 100m thick (Groundwater Relief). Water table depths range from 4 m to 60 m depth, and groundwater is typically unconfined. Abstraction boreholes range from 10 m to 70 m, and borehole yields are generally low.
||The fractured/weathered aquifers have low storage potential and do not contain large amounts of groundwater.
||
||Recharge is variable depending on rainfall and surface runoff.
|}

==Groundwater Use and Management==

The Ministry of Water Resources and Irrigation have developed an online Water Information Management System (WIMS), which can be accessed online through the [https://www.waterpointdata.org/data-sources/water-information-management-system-wims-developed-ministry-water-resources-and WPDx website]

=== Transboundary aquifers===

For further information about transboundary aquifers, please see the [[Transboundary aquifers | Transboundary aquifers resources page]].

==References==

References with more information on the geology and hydrogeology of South Sudan can be accessed through the [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=listResults&title_search=&author_search=&category_search=&country=SS&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive]. There may also be information on South Sudan in older literature relating to [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=listResults&title_search=&author_search=&category_search=&country=SD&placeboolean=AND&singlecountry=1 Sudan] in the Africa Groundwater Literature Archive.

Abdelhakam E. Mohamed, Ali Sayed Mohammed. 2008. Stratigraphy and Tectonic Evolution of the oil producing horizons of Muglad Basin, Sudan. J.Sc. Tech Vol. 9(1)

African Development Bank Group. 2013. [https://www.afdb.org/en/countries/east-africa/south-sudan/infrastructure-action-plan-in-south-sudan-a-program-for-sustained-strong-economic-growth/ South Sudan: An Infrastructure Action Plan. A Program for Sustained Strong Economic Growth].

GRAS (Geological Research Authority of the Sudan). 1981. [https://esdac.jrc.ec.europa.eu/content/geological-map-sudan Geological map of Sudan]. Scale 1:10,000,000

Hydrogeological map of Sudan, National Corporation for Development of Rural Water Resources, Khartoum, Sudan, 1989

Shahin, M. 1985. [https://books.google.com/books?id=FhRHvYmTPqQC Hydrology of the Nile Basin], Elsevier.

Schlüter T. 2006. [http://www.geokniga.org/bookfiles/geokniga-geological-atlas-africa.pdf Geological Atlas of Africa]. Springer, Berlin-Heidelberg-New York.

Worrell GA. 1957. [https://www.jstor.org/stable/41710729 A simple introduction to the geology of the Sudan]. Sudan Notes and Records, Vol. 38, pp 2-9. University of Khartoum.

''See particularly'':

: [https://www.afdb.org/fileadmin/uploads/afdb/Documents/Generic-Documents/South%20Sudan%20Infrastructure%20Action%20Plan%20-%20%20A%20Program%20for%20Sustained%20Strong%20Economic%20Growth%20-%20Chapter%205%20-%20Lands%20and%20Water%20Resource%20Management.pdf Chapter 5: Lands and Water Resource Management]

: [https://www.afdb.org/fileadmin/uploads/afdb/Documents/Generic-Documents/South%20Sudan%20Infrastructure%20Action%20Plan%20-%20%20A%20Program%20for%20Sustained%20Strong%20Economic%20Growth%20-%20Chapter%209%20-%20Water%20Supply%20and%20Sanitation.pdf Chapter 9: Water Supply and Sanitation].

Groundwater Development Reports from [http://groundwater-relief.org/ Groundwater Relief]

: Burrows, G., Mannix, N., Sir, B., Krom, T. 2016. Bentiu POC Hydrogeological Assessment. Groundwater Relief Report.

: Burrows, G., Krom, T., Marsili, A., Michel, F. 2014. Hydrogeological Assessment of the Maban Aquifer. Hydrogeologists without Borders (Groundwater Relief) Report.

: Burrows, G., Odero, D., Wong, H. 2014. PoC3 Camp, Juba, South Sudan – hydrogeological desk study. Hydrogeologists without Borders (Groundwater Relief) Report.

United Nations. 1988. [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060049 Groundwater in North and West Africa: Sudan]. United Nations Department of Technical Cooperation for Development and Economic Commission for Africa/Natural Resources/Water Series No. 18, ST/TCD/5.

Return to:
[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]


[[Category:Hydrogeology by country|s]]
[[Category:Africa Groundwater Atlas]]

File:Zimbabwe Geology3.png

2019-09-12T14:26:38Z

KirstyUpton: /* Licencing */

== Licencing ==
__notoc__
{|class="wikitable" style="width:100% style="background:#f0f8ff; font-size:100%"
| This image is licensed under a [https://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License]. For full details see the [[Africa Groundwater Atlas Terms of Use | Terms of use]] page.
|}
[[Category:License tags]]

File:Zimbabwe Hydrogeology3.png

2019-09-12T14:25:07Z

KirstyUpton: /* Licencing */

File:Zambia Hydrogeology3.png

2019-09-12T14:23:26Z

KirstyUpton: /* Licencing */

File:Zambia Geology3.png

2019-09-12T14:22:26Z

KirstyUpton: /* Licencing */

File:Uganda Hydrogeology3.png

2019-09-12T14:21:24Z

KirstyUpton: /* Licencing */

File:Uganda Geology3.png

2019-09-12T14:20:33Z

KirstyUpton: /* Licencing */

File:Tunisia Hydrogeology4.png

2019-09-12T14:19:14Z

KirstyUpton: /* Licencing */

File:Tunisia Geology4.png

2019-09-12T14:18:17Z

KirstyUpton: /* Licencing */

File:Togo Hydrogeology4.png

2019-09-12T14:17:17Z

KirstyUpton: /* Licencing */

File:Togo Geology4.png

2019-09-12T14:16:33Z

KirstyUpton: /* Licencing */

File:Tanzania Hydrogeology3.png

2019-09-12T14:13:16Z

KirstyUpton: /* Licencing */

File:Tanzania Geology3.png

2019-09-12T14:12:06Z

KirstyUpton: /* Licencing */

File:Sudan Hydrogeology4.png

2019-09-12T14:10:44Z

KirstyUpton: /* Licencing */

File:Sudan Geology4.png

2019-09-12T14:09:33Z

KirstyUpton: /* Licencing */

File:Sudan UnconsolidatedGeology.png

2019-09-12T14:08:34Z

KirstyUpton: /* Licencing */

File:SouthSudan Hydrogeology3.png

2019-09-12T14:07:05Z

KirstyUpton: /* Licencing */

File:SouthSudan Geology3.png

2019-09-12T14:05:54Z

KirstyUpton: /* Licencing */

File:Somalia Hydrogeology4.png

2019-09-12T13:53:31Z

KirstyUpton: /* Licencing */

File:Somalia Geology4.png

2019-09-12T13:52:18Z

KirstyUpton: /* Licencing */

File:Sierra Leone Hydrogeology3.png

2019-09-12T13:50:27Z

KirstyUpton: /* Licencing */

File:Sierra Leone Geology3.png

2019-09-12T13:49:26Z

KirstyUpton: /* Licencing */

File:Senegal Hydrogeology5.png

2019-09-12T13:48:02Z

KirstyUpton: /* Licencing */

File:Senegal Geology5.png

2019-09-12T13:46:58Z

KirstyUpton: /* Licencing */

File:Rwanda Hydrogeology2.png

2019-09-12T13:45:10Z

KirstyUpton: /* Licencing */

File:Rwanda Geology2.png

2019-09-12T13:43:54Z

KirstyUpton: /* Licencing */

File:RepublicOfCongo Hydrogeology3.png

2019-09-12T13:41:40Z

KirstyUpton: /* Licencing */

File:RepublicOfCongo Geology3.png

2019-09-12T13:40:35Z

KirstyUpton: /* Licencing */

File:Nigeria Hydrogeology3.png

2019-09-12T13:39:16Z

KirstyUpton: /* Licencing */

File:Nigeria Geology3.png

2019-09-12T13:38:15Z

KirstyUpton: /* Licencing */

File:Niger Hydrogeology4.png

2019-09-12T13:36:57Z

KirstyUpton: /* Licencing */

File:Niger Geology4.png

2019-09-12T13:35:20Z

KirstyUpton: /* Licencing */

File:Mozambique Hydrogeology3.png

2019-09-12T13:31:38Z

KirstyUpton: /* Licencing */

File:Mozambique Geology3.png

2019-09-12T13:30:06Z

KirstyUpton: /* Licencing */

File:MoroccoWesternSahara Hydrogeology3.png

2019-09-12T13:28:31Z

KirstyUpton: /* Licencing */

File:MoroccoWesternSahara Geology3.png

2019-09-12T13:27:17Z

KirstyUpton: /* Licencing */

File:Mauritania Hydrogeology5.png

2019-09-12T13:24:12Z

KirstyUpton: /* Licencing */

File:Mauritania Geology3.png

2019-09-12T13:22:39Z

KirstyUpton: /* Licencing */

File:Mauritania UnconsolidatedGeology2.png

2019-09-12T13:21:27Z

KirstyUpton: /* Licencing */

File:Mali Hydrogeology4.png

2019-09-12T13:18:47Z

KirstyUpton: /* Licencing */

File:Mali Geology4.png

2019-09-12T13:17:46Z

KirstyUpton: /* Licencing */

File:Malawi Hydrogeology3.png

2019-09-12T13:16:14Z

KirstyUpton: /* Licencing */

File:Malawi Geology3.png

2019-09-12T13:15:15Z

KirstyUpton: /* Licencing */