Editing Hydrogeology of Tanzania
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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Tanzania | [[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Tanzania | ||
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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. | 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. | ||
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|Freshwater withdrawal as % of total renewable water resources ||5.385 || || | |Freshwater withdrawal as % of total renewable water resources ||5.385 || || | ||
|- | |- | ||
− | | | + | |Renewable groundwater resources (Million cubic metres/year) || No data || No data || No data |
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|- | |- | ||
|Groundwater produced internally (Million cubic metres/year) || ||30,000 || | |Groundwater produced internally (Million cubic metres/year) || ||30,000 || | ||
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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 overview of the geology of Tanzania at a national scale (see the [[Geology | Geology resource page]] for more details). | ||
− | + | Other geological maps at various scales are produced by the [http://www.gst.go.tz/mapproducts.html Geological Survey of Tanzania]. | |
− | + | [[File:Tanzania_Geology.png | center | thumb| 500px | 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]].]] | |
− | Other geological maps at various scales are produced by the [http://www.gst.go.tz/ Geological Survey of Tanzania] | ||
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{| class = "wikitable" | {| class = "wikitable" | ||
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|- | |- | ||
− | !colspan="4"| | + | !colspan="4"| Sedimentary – Coastal Basin |
|- | |- | ||
| | | | ||
− | || | + | ||Palaeozoic - Recent |
− | || | + | ||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 | ||
|- | |- | ||
− | + | | 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 |
− | |||
− | |||
− | |||
|- | |- | ||
+ | | 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. | ||
− | + | The sedimentary sequence of the Karroo System reaches 7000 m thick. | |
|- | |- | ||
− | | | + | | Upper Mesozoic Sedimentary |
− | || | + | || Upper Mesozoic |
− | || | + | ||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"| | + | !colspan="4"| Precambrian Metasedimentary |
|- | |- | ||
− | | | + | | Bukoban System and Mozambique Belt |
− | || | + | ||Upper Proterozoic |
− | || | + | || 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 | + | |
− | + | The Mozambique Belt contains granitoids, granulite, meta-anorthosites, gneisses, amphibolites, marbles, pegmatites, mafic and ultramafic rocks, migmatites, quartzites and schists. | |
− | + | || The rocks of the Bukoban System are unmetamorphosed, except where they have been subjected to local cataclasis. | |
+ | |||
+ | The rocks of the Mozambique Belt are intensely metamorphosed and deformed. | ||
|- | |- | ||
− | | | + | !colspan="4"|Igneous |
− | |||
− | |||
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|- | |- | ||
− | + | | Granitic Rocks | |
− | |||
− | |Granitic Rocks | ||
||Archean - Proterozoic | ||Archean - Proterozoic | ||
− | || | + | ||Granitic rocks are subdivided into syn-, post-, and late-orogenic. |
− | + | 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. | ||
+ | |- | ||
+ | |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 | ||
|- | |- | ||
− | | | + | | Ubendian, Usagaran, and Karagwe-Ankolean Systems |
− | Ubendian, Usagaran, and Karagwe-Ankolean Systems | + | || Lower and Middle 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 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. | ||
+ | || 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 | ||
|- | |- | ||
− | | | + | | 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 | + | The Dodoman System is the oldest and is of amphibolites facies. |
+ | |||
+ | There are also rocks of the Nyanzian and Kavirondian Systems, which include gneiss, schist, quartzite, migmatite, amphibolite and granulite. | ||
− | The | + | 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 [[ | + | 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 [[Hydrogeology Map | Hydrogeology map resource page]] for more details). |
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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]. | 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_Hydrogeology.png]] [[File: Hydrogeology_Key.png | 500x195px]] | ||
− | + | ====Unconsolidated==== | |
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− | ====Unconsolidated | ||
{| 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 | ||
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|| | || | ||
|- | |- | ||
− | | | + | |Karroo Sandstone Aquifer |
− | ||Sandstones and conglomerates of the | + | ||Sandstones and conglomerates of the Karroo System are characterised by intergranular flow and storage, which can be locally enhanced by secondary fracture permeability. |
The aquifer is generally unconfined. | The aquifer is generally unconfined. | ||
− | Boreholes commonly provide yields of 0.1 | + | Boreholes commonly provide yields of 0.1-5 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. | + | ||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. |
|| | || | ||
|| | || | ||
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==References== | ==References== | ||
− | Many of the references below, and others relating to the hydrogeology of Tanzania, can be seen in the [ | + | 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=== | ===General online resources=== | ||
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===Key Hydrogeology References=== | ===Key Hydrogeology References=== | ||
− | + | ||
+ | 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 | ||
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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. | ||
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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. | ||
− | + | 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 | ||
− | + | DHV. 1984. Regional Water Master Plans for Morogoro. Ministry of Water Tanzania | |