Hydrogeology of Sudan

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Africa Groundwater Atlas >> Hydrogeology by country >> Hydrogeology of Sudan

Authors

Abdel Hafiz Gadelmula, University of Khartoum, Sudan

Kirsty Upton, Brighid Ó Dochartaigh, British Geological Survey, UK

Geographical Setting

Map of Sudan (For more information on the datasets used in the map see the geography resources section)

General

Sudan is the third largest country in Africa. Its terrain is generally flat, with several mountain ranges: in the west the Marrah Mountains rise to around 3000 m, and in the east are the Red Sea Hills.

Estimated Population in 2013* 37,964,306
Rural Population (% of total) (2013)* 66.5%
Total Surface Area* 2,376,000 sq km
Agricultural Land (% of total area) (2012)* 47.4%
Capital City Khartoum
Region Northern Africa
Border Countries Egypt, Eritrea, Ethiopia, South Sudan, Central African Republic, Chad, Libya.
Annual Freshwater Withdrawal (2013)* 26,930 Million cubic metres
Annual Freshwater Withdrawal for Agriculture (2013)* 96.2%
Annual Freshwater Withdrawal for Domestic Use (2013)* 3.5%
Annual Freshwater Withdrawal for Industry (2013)* 0.3%
Rural Population with Access to Improved Water Source (2012)* 50.2%
Urban Population with Access to Improved Water Source (2012)* 66%

* Source: World Bank

Climate

The centre and north of Sudan are extremely dry. Rainfall increases towards the south. There are distinct wet and dry seasons, with the rainy season in the north between July and September, and in the south between June and November.


Rainfall time-series and graphs of monthly average rainfall and temperature for each individual climate zone can be found on the Sudan Climate Page.


Average monthly precipitation for COUNTRY showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall Average monthly temperature for COUNTRY showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature Quarterly precipitation over the period 1950-2012 Monthly precipitation (blue) over the period 2000-2012 compared with the long term monthly average (red)

For further detail on the climate datasets used see the climate resources section.

Surface water

The Nile rivers are the major perennial rivers in the country. The Blue Nile is joined by the Dinder and Rahad rivers between Sennar and Khartoum, and joins the White Nile at Khartoum to form the River Nile.

There are several dams on the Blue and White Niles, including the Sennar and Roseires Dams on the Blue Nile, and the Jebel Aulia Dam on the White Nile. There is also Lake Nubia on the Sudanese-Egyptian border.

The Ministry of Irrigation monitors river flows, and stores dataset going back several decades.







Surface Water Map of Sudan (For more information on the datasets used in the map see the surface water resources section)

Soil

Soil Map of Sudan (For map key and more information on the datasets used in the map see the soil resources section)

Land cover

The centre and north of Sudan are dry with areas of desert, such as the Nubian Desert to the northeast and the Bayuda Desert to the east. In the south there are swamps and rainforest.











Land Cover Map of Sudan (For map key and more information on the datasets used in the map see the land cover resources section)

Geology

This section provides a summary of the geology of Sudan. More detail can be found in the references listed at the bottom of this page. Many of these references can be accessed through the Africa Groundwater Literature Archive.

The geology map on this page shows a simplified version of the geology at a national scale (see the Geology resources page for more details). The map is available to download as a shapefile (.shp) for use in GIS packages. Other published geological maps are listed in the Geology; key references section, below.


Simplified geological map of Sudan


Summary

Sudan's geology ranges from Precambrian crystalline basement rocks to Quaternary unconsolidated alluvial deposits. The geological history saw a long period of erosion at the end of the Precambrian to the late Palaeozoic, removing most of the previously deposited sedimentary cover with the exceptions of a few isolated outcrops, such as at Wawa (Kordofan), near the Chad border, near the Jabal Uweinat and in northwest Sudan (UN 1988).

During the Mesozoic, Nubian Sandstone deposits were laid down, and survive particularly in basins within the basement and Palaeozoic cover. Tectonic movements of the Rift system in the middle and late Tertiary led to the formation of vast structural basins, such as the Bara, Dinder and Baggara. A volcanic phase throughout the late Tertiary and into the early Quaternary produced the Jabel Mara and Meidobe basalts and the basaltic flows of the Bayoda desert and the Gedarif region. In the Plio-Pleistocene period, these Tertiary basins received thick alluvial and lacustrine deposits, of the Um Ruwaba formation (UN 1988).

A major shear zone, the Central African Shear Zone, runs through the central part of Sudan.


Geological Environments
Key Formations Period Lithology Structure
Unconsolidated sedimentary deposits
Gezira Formation, Alatshan Formation, Gash deposits Quaternary The youngest sediments in Sudan include alluvial silts and clays with occasional sands of the Nile and other major valleys; Red Sea coastal deposits of continental gravels, sands, silts and clays, and marine coral limestones; Kordofan aeolian dune sands; and black clay plains (UN 1988). They include the Gezira and Alatshan and Gash formations, and have thickness ranging up to just less than 100 m.
Um Ruwaba Formation Late Tertiary to Quaternary The Um Ruwaba Formation covers about 20% of the country, within two large trenches in the centre and south: the Bara (including the Kordofan, Darfur and southern regions) and the Blue Nile/Rahad/Dinder area, and comprises unconsolidated alluvial and lacustrine sands, silts and clays (UN 1988). It is between 150 m and 500 m thick.
Tertiary
Sedimentary Rocks: Hudi Chert, Jabya Formation, Red Sea littoral zone deposits, Mukwar Formation, Hamamit Formation, Abu Imamma Formation, Dungunab Formation, Abu Shagra Formation, Abyad Formation Tertiary These rocks are relatively minor and mostly not shown on the geological map above.

The consolidated Hudi Chert Formation is non-marine and fossiliferous, containing very thin cherts - not more than a few metres - and found in and around the Atbara region.

Most of the other named formations are a series of undeformed sedimentary rocks occupying 10-40 km width along the coast, underlying Quaternary unconsolidated sediments, and also not shown on the geological map above. Their thickness can exceed 2 km.

The Abyad Formation crops out in northwest Sudan and comprises mostly marine sediments, including sandstones, limestones and evaporates.

Volcanic Rocks: Gedaref, Jebel Mara, Meidobe and Bayoda basalts Tertiary Basic volcanic rocks. Horizontally to gently dipping beds.
Mesozoic Sedimentary Rocks
Nubian Sandstone Upper Jurassic to Lower Cenozoic (mainly Cretaceous) The Nubian Sandstone covers almost one third of Sudan, and comprises largely horizontal or gently dipping, well stratified sandstones with layers of conglomerate and siltstone (UN 1988). It is found in the Khartoum basin, Kufra basin, Atbara basin, Blue Nile basin, Gedaref basins, Sag Elnaam basin and in Darfur. In the Khartoum basin, it exceeds 3 km in thickness. In the south, it is overlain by thick unconsolidated sediments of the Um Ruwaba Formation, while in the rest of the country it outcrops in plateaus or sub-crops below variable thicknesses of unconsolidated surface cover (UN 1988). Major faults are recognised in the Nubian Sandstone, sometimes displacing more than 2 km of sedimentary rocks, including the Jaulia fault.
Kabbabish and Wadi Hower formations, Gedaref Sandstone, Bentue Aradaiba, Zarga, Abu Gabra Mainly Cretaceous The Kababish Formation is composed of siltstones, mudstones and fine grained sandstones, and is around 100 m thick. The Wadi Hower Formation is composed of sandstones, and is around 200 m thick.

The Gedaref Sandstone Formation is located in northwest Sudan. Their thickness exceeds 100 m. There are some basic igneous intrusions within the sandstones.

The Bentue, Aradaiba and Zarga formations are sandstones and mudstones of continental origin, and their thickness can exceed 5 km.

The Abu Gabra is a sedimentary formation found in central-western Sudan.

Palaeozoic Sedimentary Rocks
Erde Ente, Nawa Formation, Sedimentary rocks of NW Sudan Cambrian to Carboniferous Outcrops of unmetamorphosed sandstones occur in the west of the country, along the Chad border.

Argillaceous sedimentary strata overlie the basement complex in central Kordofan.

Silurian deposits, alrgely fluvial-deltaic sandstones (UN 1988) occur in northwestern Sudan.

Devonian and Carboniferous rocks, including the Nawa Formation, occur around Uweinat, Sudan. They consist mainly of sandstones with schists (UN 1988).


Precambrian Basement
Precambrian Undifferentiated basement rocks are exposed over almost half of the area of Sudan, composed of metamorphosed igneous, sedimentary and metamorphic rocks. Rocks include acid gneisses, quartzites and schists. They are intruded by igneous rocks and ring complexes, mainly granites. NE-SW and NW-SE fractures are common

Hydrogeology

This section provides a summary of the hydrogeology of the main aquifers in Sudan. More information is available in the references listed in the Hydrogology: key references section at the bottom of this page, particularly unpublished MSc theses available through the University of Khartoum. More information on groundwater is also available from the Ministry of Irrigation and Ministry of Dams, and through bulletins of the Geological Research Authority of the Sudan (GRAS).

Other references can be accessed through the 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 Aquifer properties resource page for more details). The map is available to download as a shapefile (.shp) for use in GIS packages.


File:Sudan Hydrogeology.png Hydrogeology Key.png


Unconsolidated

Named Aquifers General Description Water quantity issues Water quality issues Recharge
Gezira, Atshan and Gash formations These formations consist of unconsolidated alluvial sands, silts, gravels and clays of Quaternary to Late Tertiary age. Aquifer properties are variable, depending largely on lithology, but where the alluvium is dominated by coarser grained deposits, can be high. The aquifers are typically unconfined. Water table depth ranges from 15 m to 40 m. Boreholes range between 30 m and 150 m deep.

The Gash aquifer is generally around 60 m thick. Transmissivity values of 1000 m²/day have been reported (UN 1988).

The Gezira and Atshan aquifers are around 80 m thick.

Transmissivity values of between 500 and 1500 m²/day have been given for alluvial aquifers in Darfur and the north of Sudan (UN 1988).

Water quality is usually good and fresh. During high flow periods, significant recharge to the Gezira and Atshan aquifers occurs by leakage from Blue and White Nile rivers ; and to the Gash aquifer from the Gash river.
Um Ruwaba Formation The Um Ruwaba unconsolidated aquifer covers a large area. Aquifer properties are variable, depending largely on lithology, but yields are generally lower than from consolidated sedimentary aquifers in Sudan. The aquifer can be unconfined, or locally semi-confined where permeable layers occur below clay strata at depth (UN 1988). Water table depth ranges from 10 m to 150 m.

The aquifer can be several hundreds of metres thick, but boreholes range between 30 m and 150 m deep. It has a maximum transmissivity of 200 m²/day, and median of 25 m²/day. The storage coefficient is typically 10-5 to 10-3.

The aquifer is often in hydraulic contact with underlying Nubian Sandstone and older aquifers (UN 1988).

The aquifer is used mostly for small domestic supplies and livestock watering (UN 1988). Water quality is usually good and fresh. Recharge is dominantly from rainfall infiltration, and is relatively small.

Igneous Volcanic

Named Aquifers General Description Water quantity issues Water quality issues Recharge
Gedaref basalts and Jebel Mara volcanics Groundwater occurs in fractured and weathered zones in these volcanic rocks. They form variably thick and variably productive aquifers depending on the degree of permeability developed by fracture and weathering, from a few metres to several hundreds of metres thick, and from very low to high aquifer productivity. The aquifers are typically unconfined. Boreholes abstracting water from the aquifer range from 10 m to 300 m deep. Groundwater quality is typically fresh in shallow zones to brackish in deeper aquifer zones. Recharge is variable depending on rainfall and surface runoff.

Consolidated Sedimentary - Intergranular Flow

Named Aquifers General Description Water quantity issues Water quality issues Recharge
Nubian Sandstone Formation The Nubian Sandstone is a major regional aquifer. The water-bearing sandstone strata have relatively high intergranular permeability and storage. Aquifer thickness ranges from 100 m to 2000 m. Transmissivity values generally range from 100 to 300 m²/day, although values of between 35 and 1500 m²/day have been recorded (UN 1988). Specific yield ranges from 0.01 to 0.2, and storage coefficient from 10-3 to 10-4. The aquifer is semi confined to confined. In some cases, groundwater was traditionally discharged via springs. Piezometric (potentiometric) groundwater head varies from 6 m below ground surface at Wadi Howar to 100 m deep at Baggara Basin. Boreholes are generally between 40 m and 400 m deep. Recorded borehole yields are between a few m³/hour to 400 m³/hour. Groundwater storage in the Baggara basin is estimated at 1,300,000 million m³, and in the Bara basin estimated at 45,000 million m³. Groundwater quality is generally fresh, although salinity increases down-gradient and there are local pockets of higher salinity. Recharge occurs by direct rainfall infiltration and via wadi runoff, and occasionally via leakage from the Nile rivers. Annual recharge to the Baggara basin is estimated at 30 million m³, and to the Bara basin esatimated at 15 million m³.
Gedaref Sandstone Formation The Gedaref Sandstone has relatively high intergranular permeability, and also forms a moderately to highly productive aquifer. Aquifer thickness ranges from 100 m to 2000 m. Transmissivity values range from 100 to 300 m²/day. Specific yield ranges from 0.01 to 0.2, and storage coefficient from 10-3 to 10-4. The aquifer is are semi confined to confined. Boreholes are generally between 40 m and 400 m deep. Groundwater quality is generally fresh.

Consolidated Sedimentary - Intergranular & Fracture Flow

Named Aquifers General Description Water quantity issues Water quality issues Recharge
Red Sea littoral zone Consolidated marine sediments, including coral limestones. Aquifer permeability and storage is very low. The saturated thickness of the aquifers is typically 5 m to 20 m, although the total thickness of the geological unit can exceed 1000 m. The aquifer is unconfined and the water table typically between 10 m and 30 m below the ground surface. Boreholes are generally between 10 m and 50 m deep. Water quality is generally brackish. Recharge is low.

Basement

Named Aquifers General Description Water quantity issues Water quality issues Recharge
Fractured and weathered Precambrian basement rocks Groundwater occurs in fractures and/or in shallow weathered zones, where permeability has been increased. These aquifer zones are typically between 5 m and 20 m thick, but can be thicker. 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. Groundwater quality ranges from fresh to brackish. Recharge is variable depending on rainfall and surface runoff.


Groundwater management and use

Groundwater management

The key institutions involved in groundwater are:

The National Water Corporation, which implements relevant legislation and manages all national water projects.

The Groundwater and Wadis Department, within the Ministry of Water Resources and Electricity, conducts groundwater research, and gives advice on groundwater management and abstraction.

The Specifications and Measurement Corporation sets standards for water issues in collaboration with the two institutions above.

Universities conduct research into groundwater.

Other ministries with a role in water resources are the Ministry of Agriculture and Forestry, the Ministry of Energy & Mining, and the Ministry of Environment and Physical Development.

There are national laws governing groundwater use and management, and state groundwater laws, for example specific Nyala aquifer and Gash aquifer laws.

Groundwater monitoring

Groundwater level monitoring is done by the Groundwater and Wadis Department in several places of interest, such as the wadis Nyala and Gash, and the Nubian Sandstone aquifer in the north of Sudan. Regular manual measurements aare made and continuous recording is also done.

Groundwater quality monitoring s conducted in different parts of the country by gwadis through different programs with WES and UNICEF. Unpublished reports with results from monitoring are available at the ministries.

Groundwater use

Groundwater in Sudan is used largely for human and livestock needs, with relatively small amounts of abstraction for small-scale irrigation.

Transboundary aquifers

The Nubian Sandstone aquifer is shared with Libya and Eqypt, and has been subject to extensive cross-border investigations and management activities.

The Paleozoic sedimentary aquifers in Darfur are shared with Chad.

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


References

The following references provide more information on the geology and hydrogeology of Sudan. Others can be accessed through the Africa Groundwater Literature Archive

Geology: key references

Maps:

GRAS (Geological Research Authority of the Sudan). 1964. Geological map of Sudan. Scale 1:10,000,000

GRAS (Geological Research Authority of the Sudan). 1980. Geological map of Sudan. Scale 1:5,000,000

Robertson Research Institute. 1981. Geological map of Sudan, Scale 1:1,000,000

Vail, jr. 1971. Geological map of Sudan. Scale 1:2,000,000

GRAS (Geological Research Authority of the Sudan). 2005. Geological map of Sudan.

SFB. 1991. Geological map of Northern Sudan.

Hydrogeology: key references

Most of the following are MSc theses from the University of Khartoum and can be accessed through the university.

More information on groundwater is also available from the Ministry of Irrigation and Ministry of Dams.


Adam HAM. 2007. Assessment of Ground Water Quality in Khartoum and Khartoum North. MSc Thesis, University of Khartoum

Al Haj MMI. 2014. Determination and Removal of Nitrates from Ground Water of Kassala Town - Sudan. MSc Thesis, University of Khartoum

Al Hasana K. 2011. Assessment of Ground Water Quality of Balola Area in South Kordofan. MSc Thesis, University of Khartoum

Ali ALM. 1977. Geology and Hydrogeology of the Sedimentary Basin of the Blue Nile and Its Tributaries between Wad Medani and Abu Huggar. MSc Thesis, University of Khartoum

Ali AOH. 2011. Assessment of Ground Water Quality in Al Kalakla - Al Shagra, Khartoum State, Sudan. MSc Thesis, University of Khartoum

Babiker EM. 2008. Characteristics, Assessment and Management of Ground Water Resources of the Coastal Aquifer in Tokar Delta, Eastern Sudan. PhD Thesis, University of Khartoum

Babiker SSA. 1991. Removal of Nitrates from Groundwater by Granular Activated Charcoal in Rural Area. MSc Thesis, University of Khartoum

Bakhit NAAE. 2010. Impact of Ground Water Quality on Soil Properties and Okra Productivity in Three Locations in Khartoum State. MSc Thesis, University of Khartoum

El Dali M. 2003. Aspects of the Geology and Hydrogeology of Omdurman Formation. MSc Thesis, University of Khartoum

El Hasan REM. 2011. Assessment of Ground Water Quality in East Kassala Town - Kassalla State - Sudan. MSc Thesis, University of Khartoum

El Karim AA. 1995. The Hydrogeology of the Area Between Abu Qouta and Managil (Central Sudan). MSc Thesis, University of Khartoum

Godat MDS. 2008. Groundwater Resource Assessment of the Area Between Medani and Sennar. MSc Thesis, University of Khartoum

Haddad Maha A. 1996. Ground water pollution of the Khartoum State. MSc Thesis, University of Khartoum

Ibrahim ASH. 2012. Groundwater Quality and Suitability for Irrigation in Khartoum State, Sudan. MSc Thesis, University of Khartoum

Ibrahim SME. 2004. Groundwater as a Source of Water Supply in Eastern Khartoum State, Geological Control and Quality Constraints. MSc Thesis, University of Khartoum

Imad F. 1993. Chemical Characteristics and Quality of Groundwater in Khartoum Province and Northern Gezira. MSc Thesis, University of Khartoum

Kaskos H. 1991. Hydrogeology of Sag El Naam Basin, Western Sudan. MSc Thesis, University of Khartoum

Kheir OM. 1981. Contribution to the hydrogeology of the Gefaref Basin, Eastern Sudan. MSc Thesis, University of Khartoum

Klitsch, Sonntag, Weistroffer and Elshazely. 1976. Grundwasser der zentralsahara Fossile vorraete. Geol.Rdsch, 65, 264-287, Stuttgart.

Magboul AB. 1993. Hydrogeology of the Northern Gezira Area (Central Sudan). MSc Thesis, University of Khartoum

Medd MEMA. 2007. Assessment of Ground Water Quality in Omdurman City. MSc Thesis, University of Khartoum

Medani AYA. 2004. Determination of Trace Elements in Ground Water by Two Precocncentration Methods Using Atomic Absorption Spectrometry. MSc Thesis, University of Khartoum

Mohammed FKE. 2008. Appraisal of Ground Water Used for Irrigation in Khartoum State. MSc Thesis, University of Khartoum

Mubarak BM. 1973. Geology and Hydrogeology of East Kordofan arae. MSc Thesis, University of Khartoum

Mukhtar IAH. 2000. Impact of Urbanization and Land-Use on Quality of Ground Water for Drinking Use Nitrate Content as Indicator. MSc Thesis, University of Khartoum

Ragab ER, Mustafa E and Adam OA. 1983. Groundwater investigation Elseleim and Al Khawi basin project, Northern State, Sudan. Ground water Administration unpublished report.

Rahman HIAA. 2009. Groundwater Management of Wadi Nyala Using Visual Modflow Model. MSc Thesis, University of Khartoum

Rahman MGAA. 2013. Impact of Effluent from Wad Dafiaa (Khartoum North) Wastewater Treatment Plant on Soil and Ground Water Quality. MSc Thesis, University of Khartoum

Razig SA. 1999. Groundwater, hydrogeology and sanitation, Northern Sudan. PhD Thesis, University of Khartoum

Razig SAA. 1990. Assessment of Groundwater Potential in Lower River Atbara and its Role in Combating Desertification. MSc Thesis, University of Khartoum

Rodwan Rashid A. 2000. Hydrogeology of the area between Kamlin and El Masid, east of the Blue Nile. MSc Thesis, University of Khartoum

Saeed EM. 1976. Hydrogeology of Khartoum province and northern Gezira. Bull no. 29, Geological Research Authority, Khartoum.

Sheriff YA. 1993. An Investigation Into the Principal Causes of Groundwater Depletion at Wadi El Bangadeed, El Obeid Area, Kordofan State. MSc Thesis, University of Khartoum

Suluiaman OASI. 2014. Groundwater Assessment in the State of Khartoum Using Water Quality Index. MSc Thesis, University of Khartoum

Tayall AM. 1995. Ground water hydrogeology east of Sennar. MSc Thesis, University of Khartoum

Tear Fund / GAD Consult. A Geophysical study for siting water wells at Abu Hadid Region in Eastern Darfur State.

UN. 1988. Sudan, in Ground water in North and West Africa. United Nations Natural Resources/Water Series No. 18, ST/TCD/5, Department of Technical Cooperation for Development and Economic Commission for Africa. http://www.bgs.ac.uk/africagroundwateratlas/fulldetails.cfm?id=AGLA060049

Wani NHO. 1994. A Study on Groundwater Quality in the Eastern Bank of the White Nile - Khartoum State - Sudan. MSc Thesis, University of Khartoum

Yousif TYM. 2002. Ground water quality and pollution in Sinnar State, Sudan. MSc Thesis, University of Khartoum


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