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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Tanzania
+
[[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Tanzania
 
 
[[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]]]
 
 
 
The area of present-day Tanzania has been inhabited since pre-historic times, first by hunter-gatherers, and since at least 2000 years ago by farmers. Travellers and traders from the Persian Gulf and India began visiting coastal areas in the early 1st millennium AD, and Arab trading posts were set up long before the 14th century. Portugal took control of some coastal areas and parts of Zanzibar from the 15th century, before Omani Arabs claimed Zanzibar in the mid 19th century, which subsequently played an important role in Arab-controlled slave and spice trades. The mainland part of Tanzania was part of German East Africa from 1884, while Britain took control of Zanzibar. After World War I, the part of German East Africa that became Tanzania (then called Tanganyika) was claimed by Britain. Tanganyika became independent in 1961, and Zanzibar in 1963, and they merged in 1964 to become Tanzania.
 
 
 
After independence, the country embraced the ideology of African socialism, with a single party state, transitioning to a multiparty political system in 1992. The first president, Julius Nyerere’s, policy of emphasising national unity and discouraging ethnic divisions helped provide relative political stability. Demands for Zanzibar’s independence from the rest of Tanzania have become stronger in the 21st century.
 
 
 
Tanzania’s economy is heavily based on agriculture, which accounts for a quarter of GDP and 85% of exports, including sugar, cotton, cashews, coffee and sisal. Gold mining provides valuable export income, along with some petrochemicals. Tourism is a growth industry, boosted by visits to Mount Kilimanjaro, Zanzibar and wildlife destinations. Strict laws protect wildlife, but poachers pose a constant threat.
 
 
 
Tanzania has relatively abundant water resources, with relatively high, but seasonal, rainfall and a number of major rivers and lakes. Most rural areas rely on groundwater from communal boreholes for water supply, and many piped urban supplies depend on groundwater. The post-independence policy of collective villagisation, intended to make the provision of infrastructure more efficient, included the rural water supply programme that aimed to supply free and safe water within 400m of every household within 20 years. However, in the 2000s access to improved water supplies has declined, especially in urban areas.
 
 
 
  
 
==Authors==
 
==Authors==
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'''Hosea Sanga''', Department of Water Resources, Ministry of Water and Irrigation, Tanzania
 
'''Hosea Sanga''', Department of Water Resources, Ministry of Water and Irrigation, Tanzania
  
'''Dr Kirsty Upton''', '''Brighid Ó Dochartaigh''', British Geological Survey, UK
+
'''Kirsty Upton''', '''Brighid Ó Dochartaigh''', British Geological Survey, UK
 
 
'''Dr Imogen Bellwood-Howard''', Institute of Development Studies, UK
 
 
 
Please cite this page as: Sangea, Upton, Ó Dochartaigh and Bellwood-Howard, 2018.
 
 
 
Bibliographic reference: Sangea H, Upton K, Ó Dochartaigh BÉ and Bellwood-Howard, I. 2018. Africa Groundwater Atlas: Hydrogeology of Tanzania. British Geological Survey. Accessed [date you accessed the information]. http://earthwise.bgs.ac.uk/index.php/Hydrogeology_of_Tanzania
 
 
 
==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==
 
==Geographical Setting==
  
[[File:Tanzania_Political.png | right | frame | Tanzania. 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]].]]
+
[[File:Tanzania_Political.png | right | frame | Political Map of Tanzania (For more information on the datasets used in the map see the [[Geography | geography resources section]])]]  
  
 
===General===
 
===General===
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{| class = "wikitable"
 
{| class = "wikitable"
 
|-
 
|-
|Capital city || Dodoma
+
|Estimated Population in 2013* || 49,253,126
 
|-
 
|-
|Region || Eastern Africa
+
|Rural Population (% of total)* || 70%
 
|-
 
|-
|Border countries || Kenya, Uganda, Rwanda, Burundi, Democratic Republic of the Congo, Zambia, Malawi, Mozambique
+
|Total Surface Area* || 885,800 sq km
 
|-
 
|-
|Total surface area* || 947,300 km<sup>2</sup>  (94,730,000 ha)
+
|Agricultural Land (% of total area)* || 46%
 
|-
 
|-
|Total population (2015)* || 53,470,000
+
|Capital City || Dodoma
 
|-
 
|-
|Rural population (2015)* ||36,942,000 (69%)
+
|Region || Eastern Africa
 
|-
 
|-
|Urban population (2015)* || 16,528,000 (31%)
+
|Border Countries || Kenya, Uganda, Rwanda, Burundi, Democratic Republic of the Congo, Zambia, Malawi, Mozambique
 
|-
 
|-
|UN Human Development Index (HDI) [highest = 1] (2014)*|| 0.5212
+
|Annual Freshwater Withdrawal (2013)* || 5184 Million cubic metres
 +
|-
 +
|Annual Freshwater Withdrawal for Agriculture* || 89%
 +
|-
 +
|Annual Freshwater Withdrawal for Domestic Use* || 10%
 +
|-
 +
|Annual Freshwater Withdrawal for Industry* || <1%
 +
|-
 +
|Rural Population with Access to Improved Water Source* || 44%
 +
|-
 +
|Urban Population with Access to Improved Water Source* || 78%
 
|}
 
|}
  
<nowiki>*</nowiki> Source: [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en FAO Aquastat]
+
<nowiki>*</nowiki> Source: World Bank
  
  
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The central plateau region of Tanzania is classified as a hot arid steppe climate, while the northern and southern regions are predominantly tropical savannah. The highland areas in the northeast and southwest of the country have temperate climates with dry winters and warm or hot summers. These climate regions are reflected in the spatial variations in observed average annual temperature and precipitation across Tanzania.  
 
The central plateau region of Tanzania is classified as a hot arid steppe climate, while the northern and southern regions are predominantly tropical savannah. The highland areas in the northeast and southwest of the country have temperate climates with dry winters and warm or hot summers. These climate regions are reflected in the spatial variations in observed average annual temperature and precipitation across Tanzania.  
 +
 +
<gallery widths="375px" heights=365px mode=nolines>
 +
File:Tanzania_ClimateZones.png |Koppen Geiger Climate Zones
 +
File:Tanzania_ClimatePrecip.png |Average Annual Precipitation
 +
File:Tanzania_ClimateTemp.png |Average Temperature
 +
</gallery>
  
 
There are temporal variations in precipitation and temperature across Tanzania. Temperature is generally lower during the winter months of June to August, and highest during November and December. Precipitation is consistently low from June to September, and is higher and more variable during the summer months.   
 
There are temporal variations in precipitation and temperature across Tanzania. Temperature is generally lower during the winter months of June to August, and highest during November and December. Precipitation is consistently low from June to September, and is higher and more variable during the summer months.   
  
[[File:Tanzania_ClimateZones.png | 375x365px |Koppen Geiger Climate Zones]][[File:Tanzania_ClimatePrecip.png | 375x365px |Average Annual Precipitation]][[File:Tanzania_ClimateTemp.png | 375x365px |Average Temperature]]
+
Rainfall time-series and graphs of monthly average rainfall and temperature for each climate zone can be found on the [[Climate of Tanzania | Tanzania Climate Page]].  
  
[[File:Tanzania_pre_Monthly.png| 255x124px| Average monthly precipitation for Tanzania showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File:Tanzania_tmp_Monthly.png| 255x124px| Average monthly temperature for Tanzania showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File:Tanzania_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File:Tanzania_pre_Mts.png|255x124px | Monthly precipitation (blue) over the period 2000-2012 compared with the long term monthly average (red)]]
+
[[File:Tanzania_pre_Monthly.png| 255x124px| Average monthly precipitation for Tanzania showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File:Tanzania_tmp_Monthly.png| 255x124px| Average monthly temperature for Tanzania showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File:Tanzania_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File:Tanzania_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 climate zone can be found on the [[Climate of Tanzania | Tanzania Climate Page]].
+
 
+
For further detail on the climate datasets used see the [[Climate | climate resources section]].
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===
 
===Surface water===
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Tanzania Electric Supply Company (TANESCO) also monitor lake levels and river flow in selected locations.
 
Tanzania Electric Supply Company (TANESCO) also monitor lake levels and river flow in selected locations.
  
| [[File:Tanzania_Hydrology.png | frame | Major surface water features of Tanzania. 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]].]]
+
| [[File:Tanzania_Hydrology.png | frame | Surface Water Map of Tanzania (For more information on the datasets used in the map see the [[Surface water | surface water resources section]])]]
 
 
|
 
 
|}
 
|}
  
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{|
 
{|
 
|-
 
|-
 +
| [[File:Tanzania_soil.png | frame | Soil Map of Tanzania (For more information on the datasets used in the map see the [[Soil | soil resources section]])]]
  
 
|The soils of Tanzania are very varied, reflecting the complex interaction of climate, topography and geology.  
 
|The soils of Tanzania are very varied, reflecting the complex interaction of climate, topography and geology.  
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Fluvisols are widespread in central Tanzania along the floodplain of the Rufiji River and its tributaries.  
 
Fluvisols are widespread in central Tanzania along the floodplain of the Rufiji River and its tributaries.  
 
| [[File:Tanzania_soil.png | frame | Soil Map of Tanzania, from the European Commission Joint Research Centre: European Soil Portal. For more information on the map see the [[Soil | soil resource page]].]]
 
 
|
 
 
|}
 
|}
  
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|
 
|
  
| [[File:Tanzania_LandCover.png | frame | Land Cover Map of Tanzania, from the European Space Agency GlobCover 2.3, 2009. For more information on the map see the [[Land cover | land cover resource page]].]]
+
| [[File:Tanzania_LandCover.png | frame | Land Cover Map of Tanzania (For more information on the datasets used in the map see the [[Land cover | land cover resources section]])]]
 
 
|
 
|}
 
 
 
 
 
===Water statistics===
 
 
 
{| class = "wikitable"
 
| || 2002||2014||2015
 
|-
 
|Rural population with access to safe drinking water (%) || || ||  45.5
 
|-
 
|Urban population with access to safe drinking water (%) || || ||  77.2
 
|-
 
|Population affected by water related disease || No data || No data || No data 
 
|-
 
|Total internal renewable water resources (cubic metres/inhabitant/year) || ||1571 || 
 
|-
 
|Total exploitable water resources (Million cubic metres/year) || No data || No data || No data 
 
|-
 
|Freshwater withdrawal as % of total renewable water resources ||5.385 || ||
 
|-
 
|Total renewable groundwater (Million cubic metres/year) ||  ||30,000 ||
 
|-
 
|Exploitable: Regular renewable groundwater (Million cubic metres/year) || No data || No data || No data
 
 
 
|-
 
|Groundwater produced internally (Million cubic metres/year) || ||30,000 || 
 
|-
 
|Fresh groundwater withdrawal (primary and secondary) (Million cubic metres/year) || No data || No data || No data 
 
|-
 
|Groundwater: entering the country (total) (Million cubic metres/year) || No data || No data || No data 
 
|-
 
|Groundwater: leaving the country to other countries (total) (Million cubic metres/year) || No data || No data || No data 
 
|-
 
|Industrial water withdrawal (all water sources) (Million cubic metres/year) ||25 || ||
 
|-
 
|Municipal water withdrawal (all water sources) (Million cubic metres/year)  ||527 || ||
 
|-
 
|Agricultural water withdrawal (all water sources) (Million cubic metres/year) ||4,632|| ||
 
|-
 
|Irrigation water withdrawal (all water sources) <sup>1</sup> (Million cubic metres/year) ||4,425|| ||
 
|-
 
|Irrigation water requirement (all water sources) <sup>1</sup> (Million cubic metres/year) ||973 || ||
 
|-
 
|Area of permanent crops (ha) || || 2,150,000|| 
 
|-
 
|Cultivated land (arable and permanent crops) (ha) || ||15,650,000 || 
 
|-
 
|Total area of country cultivated (%) || ||16.52 || 
 
|-
 
|Area equipped for irrigation by groundwater (ha) ||386|| || 
 
|-
 
|Area equipped for irrigation by mixed surface water and groundwater (ha) || 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==
 
==Geology==
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This section provides a summary of the geology of Tanzania. 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://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].
 
This section provides a summary of the geology of Tanzania. 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://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].
  
The geology map on this page shows a simplified overview of the geology of Tanzania at a national scale (see the [[Geology | Geology resource page]] for more details).  
+
The geology map on this page shows a simplified version of the geology of Tanzania at a national scale, based on 1:5,000,000 scale mapping (see [[Geology | the Geology resources section]] for more details).  
  
[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Tanzania geology and hydrogeology map'''].
+
Other geological maps at various scales are produced by the [http://www.gst.go.tz/mapproducts.html Geological Survey of Tanzania].  
  
Other geological maps at various scales are produced by the [http://www.gst.go.tz/ Geological Survey of Tanzania], which hosts a [http://www.gmis-tanzania.com/ '''Geological and Mineral Information System'''] that shows paper geological maps available for sale, and also provides a '''digital geology map''' at a scale of 1:2 million, which is downloadable in shapefile format.
+
[[File:Tanzania_Geology.png | center | border | 500px]]
 
 
 
 
[[File:Tanzania_Geology3.png | center | thumb| 400px | Geology of Tanzania 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 Tanzania geology and hydrogeology map].]]
 
  
 
{| class = "wikitable"
 
{| class = "wikitable"
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|-
 
|-
!colspan="4"| Tertiary-Quaternary Unconsolidated Sedimentary
+
!colspan="4"| Sedimentary – Coastal Basin
 
|-
 
|-
 
|  
 
|  
||Neogene-Quaternary
+
||Palaeozoic - Recent
||Unconsolidated sediments cover large parts of the country, including alluvial sediments in valleys, coastal/marine sediments along the coast, and continental and lacustrine sediments.
+
||The coastal basin comprises sedimentary rocks of various ages, including parts of the Karroo Sandstone, which extends south-westwards from the coast at the border with Kenya to Lake Malawi. The coastal basin includes sandstone, mudstone and limestone.
||
+
||There are two major structural trends associated with faulting: the NNE-SSW Tanga Fault and the NNW-SSE Lind Fault.
 +
|-
 +
!colspan="4"| Sedimentary – Cretaceous-Tertiary
 
|-
 
|-
!colspan="4"| Cretaceous-Quaternary volcanic rocks
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| Cretaceous Sedimentary
 +
|| Cretaceous
 +
|| The Cretaceous sedimentary rocks are associated with marine regression, and consist predominantly of continental and deltaic sedimentary rocks, interbedded with thin marine beds.
 +
The continental units include sandstone, siltstone and mudstone; the marine units contain coral limestone, silty shale and mudstone.
 +
||The majority of the marine sedimentary rocks occur in southern Tanzania, with isolated deposits in the central-east and northeast of the country.
 
|-
 
|-
|
+
!colspan="4"| Sedimentary – Mesozoic-Paleozoic
||Cretaceous-Quaternary
 
||Carbonatite volcanoes began erupting in the Cretaceous and continued into the Cenozoic. Ol Doinyo Lengai is the world's only active volcano with carbonatite lava. Alkaline volcanic rocks of Neogene age are common north of Lake Nyasa and Lake Natron.
 
||Volcanism is associated with the East African Rift system.
 
 
|-
 
|-
 +
| Karroo System
 +
|| Carboniferous to Lower Jurassic
 +
|| In southwest Tanzania the Karroo sedimentary rocks are of continental origin; in the northeast they are predominantly marine.
 +
 +
The Karroo system consists mainly of sandstone, siltstone and shale, with some coal deposits.
 +
||The major basins of the Karroo System trend NNE. The smaller basins are aligned in a NW direction between Lake Nyasa and Lake Tanganyika.
  
!colspan="4"| Kimberlites
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The sedimentary sequence of the Karroo System reaches 7000 m thick.
 
|-
 
|-
|
+
| Upper Mesozoic Sedimentary
||
+
|| Upper Mesozoic
||Diamondiferous kimberlites are concentrated within the Precambrian Tanzania Craton (see below), mainly south of Lake Victoria, with outliers in the Precambrian (Proterozoic) Mobile/Orogenic Belt (see below). The main kimberlite provinces are Shinyanga-Mwadui, Mabuki, Speke Gulf, Lake Eyasi and Iramba Plateau.
+
||Sedimentary rocks of Upper Mesozoic age overlie the Karroo System and Precambrian basement. They were deposited in coastal basins that formed during the breakup of Gondwana, and represent alternating transgressive and regressive deposits. They comprise largely limestone, sandstone, shale, marl and local evaporites.  
||
+
|| The Upper Mesozoic rocks occur along the coastal margin of Tanzania and in parts of the rift trough.
 
|-
 
|-
!colspan="4"| Sedimentary – Jurassic-Tertiary
+
!colspan="4"| Precambrian Metasedimentary
 
|-
 
|-
|Cretaceous Sedimentary
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| Bukoban System and Mozambique Belt
||Late Jurassic to Tertiary
+
||Upper Proterozoic
||Late Jurassic to Tertiary sedimentary rocks in Tanzania are associated with a long-lasting marine regression, which led to the deposition of mainly continental and deltaic sedimentary rocks, interbedded with thin marine beds. The The continental units include sandstone, siltstone and mudstone. The marine units contain coral limestone, silty shale and mudstone, and are mostly found in southern Tanzania, with isolated outcrops in the central-east and northeast.
+
|| The Bukoban System comprises sedimentary rocks of anorogenic and continental origin, amygdaloidal basalts, and andesites. The sedimentary rocks of the Bukoban System include sandstones, siltstone, shales, red beds, chert, conglomerates, quartzites, greywackes, and dolomitic limestones.
||The sedimentary rocks were deposited in rift troughs of the East Africa Rift, trending SW-NE, and also in the coastal basin. In the coastal basin there are two major structural trends associated with faulting: the NNE-SSW Tanga Fault and the NNW-SSE Lind Fault.
+
 
|-
+
The Mozambique Belt contains granitoids, granulite, meta-anorthosites, gneisses, amphibolites, marbles, pegmatites, mafic and ultramafic rocks, migmatites, quartzites and schists.
!colspan="4"|Sedimentary – Mesozoic-Paleozoic
+
|| The rocks of the Bukoban System are unmetamorphosed, except where they have been subjected to local cataclasis.  
|-
+
 
|Karoo Supergroup
+
The rocks of the Mozambique Belt are intensely metamorphosed and deformed.
||Carboniferous to Lower Jurassic
 
||The Karoo system consists mainly of sandstone, siltstone and shale, with more minor coals, conglomerates, tillite, mudstones and limestones. In southwest Tanzania the Karoo sedimentary rocks are of continental origin; in the northeast they are predominantly marine.  
 
||The major basins of the Karoo System trend NNE. The smaller basins are aligned in a NW direction between Lake Nyasa and Lake Tanganyika. The sedimentary sequence of the Karroo System reaches 7000 m thick.  
 
 
|-
 
|-
!colspan="4"|Igneous Intrusive
+
!colspan="4"|Igneous
 
|-
 
|-
|Granitic Rocks and Pegmatites
+
| Granitic Rocks
 
||Archean - Proterozoic
 
||Archean - Proterozoic
||Intrusive igneous rocks are not distinguished on the geology map on this page, but they occur intruded into Archaean and Proterozoic rocks across Tanzania.
+
||Granitic rocks are subdivided into syn-, post-, and late-orogenic.  
  
Granitic rocks are subdivided into syn-, post-, and late-orogenic. Late-orogenic granites typically form the cores of gneiss domes, or occur in complex intrusions. Various types exist: granites that are typically intruded into Archaean and Proterozoic rocks, micro-granites, and granodiorites.  
+
The late-orogenic granites typically form the cores of gneiss domes, or occur in complex intrusions.  
  
Different types of pegmatite occur in syn-orogenic granites, migmatites, and metamorphic rocks of the Archean and Proterozoic terrains. Pegmatites are abundant in the Proterozoic Usagaran and Ubendian Systems; they are rare in the Archean Dodoman System; almost absent in the Archean Nyanzian System; and do not occur in rocks younger than Proterozoic age.  
+
Various types of late-orogenic granites exist: granites that are typically intruded into Archaean and Proterozoic rocks, micro-granites, and granodiorites.
||Granites within the Archean and Proterozoic rocks of Tanzania are scarce, small and discordant with the general structural trend. Micro-granites typically occur as lenticular masses within syn-orogenic granites in the Lake Victoria Goldfield. Granodiorites occur in several places including the Archean Lake Victoria Goldfield and Proterozoic Lupa Goldfield.  
+
||Granites within the Archean and Proterozoic rocks of Tanzania are scarce, small and discordant with the general structural trend.
 +
 
 +
Micro-granites typically occur as lenticular masses within syn-orogenic granites in the Lake Victoria Goldfield.
 +
 
 +
Granodiorites occur in several places including the Archean Lake Victoria Goldfield and Proterozoic Lupa Goldfield.
 +
|-
 +
|Pegmatite
 +
||
 +
||Different types of pegmatite occur in syn-orogenic granites, migmatites, and metamorphic rocks of the Archean and Proterozoic terrains.
 +
||Pegmatites are abundant in the Proterozoic Usagaran and Ubendian Systems; they are rare in the Archean Dodoman System; almost absent in the Archean Nyanzian System; and do not occur in rocks younger than Proterozoic age.  
 +
|-
 +
!colspan="4"| Kimberlites
 +
|-
 +
| Shinyanga-Mwadui, Mabuki, Speke Gulf, Lake Eyasi and Iramba Plateau kimberlite provinces
 +
||Cretaceous
 +
|| Diamondiferous kimberlites
 +
|| Kimberlites are concentrated in the Tanzania Precambrian Craton (see below), mainly south of Lake Victoria, with outliers in the Precambrian (Proterozoic) mobile/orogenic belts (see below).
 
|-
 
|-
 
!colspan="4"| Precambrian Mobile/Orogenic Belt
 
!colspan="4"| Precambrian Mobile/Orogenic Belt
 
|-
 
|-
|Bukoban System, Mozambique Belt (Upper Proterozoic)
+
| Ubendian, Usagaran, and Karagwe-Ankolean Systems
Ubendian, Usagaran, and Karagwe-Ankolean Systems (Lower and Middle Proterozoic)
+
|| Lower and Middle Proterozoic
||Proterozoic
+
|| The Ubendian System includes granulite, amphibolite, migmatite, gneiss, schist, quartzite and marble. Intrusive rocks are predominantly granite, but also include gabbronorites, eclogites, metamorphosed amphibolites, dolerites, peridotites and carbonatites.
||The Bukoban System comprises largely unmetamorphosed sedimentary rocks of anorogenic and continental origin, amygdaloidal basalts, and andesites. They have occasionally been subjected to local cataclasis. The sedimentary rocks of the Bukoban System include sandstones, siltstone, shales, red beds, chert, conglomerates, quartzites, greywackes, and dolomitic limestones. The rocks of the Mozambique Belt are intensely metamorphosed and deformed, and include granitoids, granulite, meta-anorthosites, gneisses, amphibolites, marbles, pegmatites, mafic and ultramafic rocks, migmatites, quartzites and schists.
 
  
The Ubendian System includes granulite, amphibolite, migmatite, gneiss, schist, quartzite and marble. Intrusive rocks are predominantly granite, but also include gabbronorites, eclogites, metamorphosed amphibolites, dolerites, peridotites and carbonatites. The Usagaran System comprises sedimentary and volcanic rocks of the Konse Group and gneisses, amphibolites and lenses of granulites of the Isimani Suite. The Karagwe-Ankolean System comprises argillaceous formations that have been slightly metamorphosed to argillites, phyllites and schists. Arenaceous formations have also been metamorphosed to quartzite.  
+
The Usagaran System comprises sedimentary and volcanic rocks of the Konse Group and gneisses, amphibolites and lenses of granulites of the Isimani Suite.  
||In the Lower and Middle Proterozoi, rocks of the Usagaran System were largely deposited in geosynclinals troughs. The Konse Group of the Usagaran System trends NE-SW and is bordered by the Tanzania Craton to the West and Isimani Suite to the East. The Isimani Suite is highly metamorphosed and is unconformably overlain by the Konse Group.
+
 
 +
The Karagwe-Ankolean System comprises argillaceous formations that have been slightly metamorphosed to argillites, phyllites and schists. Arenaceous formations have also been metamorphosed to quartzite.  
 +
|| Rocks of the Usagaran System were largely deposited in geosynclinals troughs.
 +
The Konse Group of the Usagaran System trends NE-SW and is bordered by the Tanzania Craton to the West and Isimani Suite to the East.
 +
 
 +
The Isimani Suite is highly metamorphosed and is unconformably overlain by the Konse Group.
 
|-
 
|-
 
!colspan="4"| Precambrian Craton
 
!colspan="4"| Precambrian Craton
 
|-
 
|-
|Tanzania Craton: Dodoman and Nyanzian-Kavirondian systems, Greenstone Belts
+
| The Archean Granitoid Terrains, Dodoman System and Greenstone Belts
 
||Archean
 
||Archean
 
||The craton is a composite of several different terrains of variously metamorphosed Archaean rocks.  
 
||The craton is a composite of several different terrains of variously metamorphosed Archaean rocks.  
  
The Dodoman System, in central Tanzania, is the oldest and is of amphibolites facies. It is intruded by ultramafic, mafic, and felsic rocks (granites and pegmatites discussed above).
+
The Dodoman System is the oldest and is of amphibolites facies.  
  
The Nyanzian and Kavirondian Systems are in northern Tanzania, and include gneiss, schist, quartzite, migmatite, amphibolite and granulite.
+
There are also rocks of the Nyanzian and Kavirondian Systems, which include gneiss, schist, quartzite, migmatite, amphibolite and granulite.
  
The Greenstone Belts to the south and east of Lake Victoria are regionally metamorphosed to greenschist facies, and locally metamorphosed to epidote and amphibolites facies near granitic intrusions. The Greenstone Belts include ultramafic rocks, gabbros, dolerites, granites, syenites, diorite and lamprophyries. The Greenstone Belts are also intruded by mafic to felsic intrusions of various ages.
+
The Greenstone Belts to the south and east of Lake Victoria are regionally metamorphosed to greenschist facies, and locally metamorphosed to epidote and amphibolites facies near granitic intrusions. The Greenstone Belts include ultramafic rocks, gabbros, dolerites, granites, syenites, diorite and lamprophyries.  
||
+
||The Dodoman System is intruded by ultramafic, mafic, and felsic rocks (granites and pegmatites discussed above).
 +
 
 +
The Greenstone Belts are also intruded by mafic to felsic intrusions of various ages.
 
|}
 
|}
  
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This section provides a summary of the hydrogeology of the main aquifers in Tanzania.  More information is available in the references listed at the bottom of this page. Many of these references can be accessed through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].
 
This section provides a summary of the hydrogeology of the main aquifers in Tanzania.  More information is available in the references listed at the bottom of this page. Many of these references can be accessed through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].
  
The hydrogeology map on this page shows a simplified overview of the type and productivity of the main aquifers in Tanzania, at 1:5,000,000 scale (see the [[Africa Groundwater Atlas Hydrogeology Maps | Hydrogeology map resource page]] for more details).  
+
The hydrogeology map on this page shows a simplified version of the type and productivity of the main aquifers in Tanzania, at 1:5,000,000 scale (see [[Aquifer properties| the Aquifer properties resource page]] for more details).  
 
 
[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Tanzania geology and hydrogeology map'''].
 
 
 
Tanzania is also covered by the SADC hydrogeological map and atlas (2010), available through the [https://ggis.un-igrac.org/ggis-viewer/viewer/sadcgip/public/default SADC Groundwater Information Portal].
 
 
 
  
[[File:Tanzania_Hydrogeology3.png | center | thumb| 500px | Map of hydrogeology (aquifer type and productivity) of  Tanzania 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 Tanzania geology and hydrogeology map].]].
+
[[File:Tanzania_Hydrogeology.png]] [[File: Hydrogeology_Key.png | 500x195px]]
  
 
+
====Unconsolidated====
====Unconsolidated Sedimentary====
 
 
{| class = "wikitable"
 
{| class = "wikitable"
 
|Named Aquifers||General Description||Water quantity issues||Water quality issues||Recharge
 
|Named Aquifers||General Description||Water quantity issues||Water quality issues||Recharge
 
|-
 
|-
|
+
|Name of aquifer
||Alluvial deposits are mainly seen in coastal delta regions and along river valleys. The coastal plain consists of largely unconsolidated sediments (beach sands, dunes and salt marsh), with some consolidated limestone deposits. Alluvium is found in river valleys. There are also volcano-pyroclastic sediments close to formerly active volcanoes.  
+
||Alluvial deposits are confined to delta regions along river valleys. Borehole yields vary depending on lithology, but the greatest potential lies within the volcano-pyroclastic and alluvium deposits of the Kahe Basin and Sanya Plain near Kilimanjaro. Yields typically vary between 0.2 and 2 l/s.
  
Borehole yields vary depending on lithology, but the greatest potential lies within the volcano-pyroclastic and alluvium deposits of the Kahe Basin and Sanya Plain near Kilimanjaro. Yields typically vary between 0.2 and 2 l/s.
+
The coastal plain consists of largely unconsolidated sediments (beach sands, dunes and salt marsh), with some consolidated limestone deposits.  
  
The thickness of unconsolidated aquifers is usually not well defined, but the water table depth tends to vary between 10 and 20 m. Boreholes are often drilled to depths of 100-200 m.   
+
The thickness of the alluvial aquifers is not well defined, but the water table depth tends to vary between 10 and 20 m. Boreholes are often drilled to depths of 100-200 m.   
||There are no major groundwater quantity issues.
+
|| There are no major groundwater quantity issues.
 
||Groundwater quality is generally good, with the exception of the coastal plain deposits, which are vulnerable to saline intrusion.  
 
||Groundwater quality is generally good, with the exception of the coastal plain deposits, which are vulnerable to saline intrusion.  
 
||Rainfall is the dominant source of recharge, but infiltration also occurs from rivers and lakes.
 
||Rainfall is the dominant source of recharge, but infiltration also occurs from rivers and lakes.
Line 304: Line 254:
 
|Named Aquifers||General Description||Water quantity issues||Water quality issues||Recharge
 
|Named Aquifers||General Description||Water quantity issues||Water quality issues||Recharge
 
|-
 
|-
|Coastal Sedimentary Aquifer  
+
|Coastal Sedimentary Aquifer and Karroo Sandstone Aquifer
 
||The groundwater potential of the Coastal Sedimentary Aquifer varies depending on its lithology, with higher productivity provided by the sandstones and limestones. Marls and shales are generally unproductive. The aquifer is also generally unconfined. Borehole yields in the Coastal Sedimentary Aquifer are highest in the limestone (1-6 l/s) and slightly lower in the sandstone (up to 2.5 l/s).  
 
||The groundwater potential of the Coastal Sedimentary Aquifer varies depending on its lithology, with higher productivity provided by the sandstones and limestones. Marls and shales are generally unproductive. The aquifer is also generally unconfined. Borehole yields in the Coastal Sedimentary Aquifer are highest in the limestone (1-6 l/s) and slightly lower in the sandstone (up to 2.5 l/s).  
  
The aquifer generally varies in thickness from 5-30m. The water table typically sits at a depth of 10-35 m. Boreholes are not normally drilled below a depth of 80 m.   
+
Sandstones and conglomerates of the Karroo System are characterised by intergranular flow and storage, which may be locally enhanced by secondary fracture porosity. They are generally unconfined. Boreholes in the Karroo sediments commonly provide yields of 0.1-5 l/s, but yields up to 15 l/s have also been reported.
 +
 
 +
The sedimentary aquifers generally vary in thickness from 5-30m. The water table typically sits at a depth of 10-35 m. Boreholes are not normally drilled below a depth of 80 m.   
 +
 
 
||The productivity of the Coastal Aquifer is limited due to issues with saline intrusion.
 
||The productivity of the Coastal Aquifer is limited due to issues with saline intrusion.
 
||Salinity and nitrate are common groundwater quality issues.  
 
||Salinity and nitrate are common groundwater quality issues.  
||
+
||  
|-
+
|}
|Karoo Sandstone Aquifer
 
||Sandstones and conglomerates of the Karoo System are characterised by intergranular flow and storage, which can be locally enhanced by secondary fracture permeability.
 
  
The aquifer is generally unconfined.
 
 
Boreholes commonly provide yields of 0.1 to 5 l/s, but yields up to 15 l/s have also been reported.
 
||The aquifer generally varies in thickness from 5 - 30m. The water table typically sits at a depth of 10 - 35 m. Boreholes are not normally drilled below a depth of 80 m.
 
||
 
||
 
|}
 
  
 
====Basement====
 
====Basement====
Line 438: Line 382:
 
There are currently no significant issues concerning the management of these aquifers.  
 
There are currently no significant issues concerning the management of these aquifers.  
  
For more general information about transboundary aquifers, please see the [[Transboundary aquifers | Transboundary aquifers resource page]]
+
For more general information about transboundary aquifers, please see the [[Transboundary aquifers | Transboundary aquifers resources page]]
  
 
=== Groundwater monitoring===
 
=== Groundwater monitoring===
Line 456: Line 400:
 
==References==
 
==References==
  
Many of the references below, and others relating to the hydrogeology of Tanzania, can be seen in the [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=listResults&title_search=&author_search=&category_search=&country_search=TZ&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive].  
+
Many of the references below, and others relating to the hydrogeology of Tanzania, can be seen in the [http://www.bgs.ac.uk/africagroundwateratlas/searchResults.cfm?title_search=&author_search=&category_search=&country_search=TZ&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive].  
 
 
===General online resources===
 
 
 
[https://ggis.un-igrac.org/ggis-viewer/viewer/sadcgip/public/default SADC Groundwater Information Portal]
 
 
 
[http://www.sadc.int/themes/natural-resources/water/ General information on surface water and groundwater resources in SADC]
 
 
 
  
 
===Key Geology References===
 
===Key Geology References===
Line 473: Line 410:
 
===Key Hydrogeology References===
 
===Key Hydrogeology References===
  
AB Brokonsult. 1980. Tabora Region Water Master Plan: Hydrogeological Studies. Ministry of Water Tanzania
+
 
 +
Shindo S. 1989. The study on the Recharge Mechanism and Development of Groundwater in the Inland Area of Tanzania. Progress report of the Japan-Tanzania joint Research 4. Chiba University, Chiba, Japan.
 +
 
 +
SADC. 2010. Hydrogeological Map of Tanzania.
  
 
Carl Bro, Cowi Consult, Kampax-Kruger. 1982. Regional Water Master Plans for Iringa, Ruvuma and Mbeya Regions, Hydrogeology Vol 9. Ministry of Water for Tanzania.
 
Carl Bro, Cowi Consult, Kampax-Kruger. 1982. Regional Water Master Plans for Iringa, Ruvuma and Mbeya Regions, Hydrogeology Vol 9. Ministry of Water for Tanzania.
  
 
Coster FM. 1960. Underground water in Tanganyika
 
Coster FM. 1960. Underground water in Tanganyika
 
DHV. 1984. Regional Water Master Plans for Morogoro. Ministry of Water Tanzania
 
 
Mato. 2002. Groundwater Pollution in Urban Dar es Salaam, Tanzania: Assessing Vulnerability and Protection Priorities. Technical University, Eindhoven
 
  
 
Mjemah IC. 2007. Hydrogeological and Hydrogeochemical Investigation of a Coastal Aquifer in Dar-es-Salaam, Tanzania. Laboratory for Applied Geology and Hydrogeology, Geological Institute, Ghent University.  
 
Mjemah IC. 2007. Hydrogeological and Hydrogeochemical Investigation of a Coastal Aquifer in Dar-es-Salaam, Tanzania. Laboratory for Applied Geology and Hydrogeology, Geological Institute, Ghent University.  
Line 487: Line 423:
 
Mjemah IC, Van Camp MC and Walraevens K. Groundwater exploitation and recharge rate estimation of a quaternary sand aquifer in Dar-es-Salaam area, Tanzania.
 
Mjemah IC, Van Camp MC and Walraevens K. Groundwater exploitation and recharge rate estimation of a quaternary sand aquifer in Dar-es-Salaam area, Tanzania.
  
SADC. 2010. Hydrogeological Map of Tanzania.
+
Mato. 2002. Groundwater Pollution in Urban Dar es Salaam, Tanzania: Assessing Vulnerability and Protection Priorities. Technical University, Eindhoven
 +
 
 +
AB Brokonsult. 1980. Tabora Region Water Master Plan: Hydrogeological Studies. Ministry of Water Tanzania
  
Shindo S. 1989. The study on the Recharge Mechanism and Development of Groundwater in the Inland Area of Tanzania. Progress report of the Japan-Tanzania joint Research 4. Chiba University, Chiba, Japan.
+
DHV. 1984. Regional Water Master Plans for Morogoro. Ministry of Water Tanzania
  
  
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[[Category:Hydrogeology by country|t]]
 
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[[Category:Africa Groundwater Atlas]]
 

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