Difference between revisions of "Hydrogeology of Niger"

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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]  >> Hydrogeology of Niger
 
[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]  >> Hydrogeology of Niger
  
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Niger is the largest country in West Africa, with some 80% of its area within the Sahara desert. Since independence from French colonialism in 1958, the country has seen alternate periods of civil and military rule. Currently a multi-party democracy, Niger faces significant development challenges. It has one of the lowest literacy rates in the world.  
 
Niger is the largest country in West Africa, with some 80% of its area within the Sahara desert. Since independence from French colonialism in 1958, the country has seen alternate periods of civil and military rule. Currently a multi-party democracy, Niger faces significant development challenges. It has one of the lowest literacy rates in the world.  

Revision as of 17:36, 8 November 2018

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

  This page is being updated. Please check back soon for updates.

Niger is the largest country in West Africa, with some 80% of its area within the Sahara desert. Since independence from French colonialism in 1958, the country has seen alternate periods of civil and military rule. Currently a multi-party democracy, Niger faces significant development challenges. It has one of the lowest literacy rates in the world.

The Nigerien economy relies heavily on export revenue from uranium ore. Oil exploration by private companies started after 1970, and the state began producing oil after 2011. However, the main livelihood activity for the majority of people in Niger remains subsistence and small-scale commercial agriculture. As well as internal markets, foreign exchange earnings from livestock are considered to be the largest source of export revenue after mining and oil exports.

Dominantly arid, with low and irregular rainfall, most of Niger’s rivers are ephemeral, except for the Niger River. Other surface water resources are numerous internal drainage ponds, and some dammed reservoirs. Large scale irrigation schemes mainly use surface water. Niger has seen a number of recent droughts (eg 2005/6, 2010). Groundwater is a vital resource for rural domestic water supplies, for some piped urban water supplies, and for small-scale irrigation.


Compilers

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

Imogen Bellwood-Howard, Institute for Development Studies, UK.

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

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

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 Terms of use for more information.

Geographical Setting

Niger. 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 resource page.

General

Capital City Niamey
Region Western Africa
Border Countries Nigeria, Benin, Burkina Faso, Mali, Algeria, Libya, Chad.
Total Surface Area* (km2) 1,266,700
Total Population (2015)** 19,899,000
Rural Population** (2015) 16,290,000
Urban Population** (2015) 3,609,000
Human Development Index (HDI) (highest = 1)** 0.3483

* Source: World Bank ** Source: FAO Aquastat

Niger is a landlocked country in West Africa, with mainly gentle relief.


Climate

The north and largest part of Niger has an arid Saharan climate; the southern part has a semi-arid Sahelian-Sudanian climate.

Rainfall is highly irregular both spatially, seasonally and inter-annually, but in general there is a long dry season from October to May, and a shorter rainy season from June to September.

Evaporation varies between 1,700 mm and 2,100 mm of water per year (FAO Aquastat).


Koppen Geiger Climate ZonesAverage Annual PrecipitationAverage Temperature

Average monthly precipitation for Niger showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall Average monthly temperature for Niger 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)


More information on average rainfall and temperature for each of the climate zones in Niger can be seen at the Niger 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 resource page.

Surface water

There are two major river basins in Niger: the watershed of eastern Niger, which are dominated by the Lake Chad basin and the Komadougou Yobe; and the watershed of Western Niger, which is dominated by the Niger River and its tributaries. Most surface runoff is in the Niger River (90%) and its tributaries from the right bank.

In addition, Niger's surface drainage network includes over 1,000 ponds, of which about 175 are permanent. These ponds are often hydraulically connected to aquifers: for example, the Tabalack and Madarounfa ponds (FAO Aquastat).

Niger currently has about 10 dams, with a theoretical total capacity of about 76 million cubic metres (FAO Aquastat).

Niger had an area of ​​4,317,589 ha of internationally important wetlands in 2013. The W" National Park was the first site designated in 1987, and since then 11 other RAMSAR sites have been designated, including wetlands of the Niger Valley, Korama and Komadougou Yobe, natural lakes and ponds, fossil streams and oases.


Major surface water features of Niger. 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 resource page.

Soil

Soils in NIger are largely sandy or sandy-clay, and typically poor in nutrients and organic matter. The cultivable soils are 80% dune and 15 to 20% percent moderately clayey hydromorphic soils (FAO Aquastat).



Soil Map of Niger, from the European Commission Joint Research Centre: European Soil Portal. For more information on the map see the soil resource page.

Land cover

Three quarters of the area of Niger is Sahara desert. The southern part of the country lies in the Sahelo-Sudan zone (FAO Aquastat).




Land Cover Map of Niger, from the European Space Agency GlobCover 2.3, 2009. For more information on the map see the land cover resource page.

Water statistics

1997 2005 2010 2012 2014 2015
Rural population with access to safe drinking water (%) 48.6%
Urban population with access to safe drinking water (%) 100%
Population affected by water related disease 3,143,000
Total internal renewable water resources per capita (cubic metres/inhabitant/year) 175.9
Total exploitable water resources (Million cubic metres/year) 5,000
Freshwater withdrawal as % of total renewable water resources 2.9
Total renewable groundwater (Million cubic metres/year) 2,500
Exploitable: Regular renewable groundwater (Million cubic metres/year) No data No data No data No data No data No data
Groundwater produced internally (Million cubic metres/year) 2,500
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)
Industrial water withdrawal (all water sources) (Million cubic metres/year) 13.7
Municipal water withdrawal (all water sources) (Million cubic metres/year) 61.7
Agricultural water withdrawal (all water sources) (Million cubic metres/year) 656.5
Irrigation water withdrawal (all water sources)1 (Million cubic metres/year) 656.5
Irrigation water requirement (all water sources)1 (Million cubic metres/year) 201.2
Area of permanent crops (ha) 100,000
Cultivated land (arable and permanent crops) (ha>) 16,000,000
Total area of country cultivated (%) 12.63
Area equipped for irrigation by groundwater (ha) 1,370
Area equipped for irrigation by mixed surface water and groundwater (ha) no data no data no data no data no data no data

These statistics are sourced from 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 Aquastat Main Database.

1 More information on irrigation water use and requirement statistics

Geology

This section provides a summary of the geology of Niger. The geology map below shows a simplified overview of the geology at a national scale. For more information on the datasets used in the map see the the Geology resource page.

Other sources of geological information

A geological map of the Republic of Niger at 1: 2 million scale, published in 1966, was published in paper form, and may be available from the Centre de Recherche Geologique et Miniere in Niamey.

A BRGM project in 2011 helped to set up a geographical information system (GIS) for geological and mining data, although it may not still be available.


Geology of Niger 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 resource page.
Geological Environments
Basin Age Lithology and Structure
Sedimentary
cross-basin Quaternary Away from the Chad and Iullemedan Basins (see below), smaller outcrops of Quaternary sediments can be found, including alluvial sands and gravels in river valleys; lacustrine silts and clays and evaporite deposits in former lake beds; and some small areas of aeolian dune sands.
Chad Basin Cretaceous-Quaternary The Chad Basin is a major geological feature: a sedimentary depositional basin that extends over large parts of a number of countries including Chad and Nigeria. In Niger, the Chad Basin extends over much of the east and north of the country. The Basin contains a great thickness of sedimentary rocks dating from the Cretaceous to Quaternary in age - it is more than 3,500 m thick at its thickest known points, although the total thickness in Niger is uncertain. These sedimentary rocks are underlain by Precambrian bedrock.

The youngest and uppermost formation is the Chad Formation, largely of Quaternary age, which can reach many hundreds of metres thick. It consists of unconsolidated fine to coarse grained sands and gravels with sandy clays. These include extensive aeolian (dune) sands, and also lacustrine (lake and lake-margin), alluvial fan and deltaic deposits. Much of the sequence is sandy or gravelly, but there are frequent lacustrine clay layers. Abrupt changes in clay and sand content are common, and the sediments usually occur as overlapping lenses.

The Chad Formation is underlain by the Continental Terminal formation, largely of Tertiary age, which consists of alternating, usually loosely consolidated, sandstones, siltstones, shales and mudstones.

Below the Continental Terminal there may be consolidated sedimentary rocks of Cretaceous age, dominantly marine but some continental sediments - including sandstones, siltsones, marls/calcareous mudstones and limestones.

Iullemeden (also called Niger) Basin Cretaceous-Quaternary The Iullemeden Basin lies immediately west of the Chad Basin and covers most of the western part of Niger. The Basin extends beyond Niger to parts of Mali, Benin and northwest Nigeria (it is called the Sokoto Basin in northwestern Nigeria). The total sedimentary sequence in the basin reaches several thousand metres thick.

The youngest and uppermost sediments in the basin are unconsolidated Quaternary sediments, including extensive aeolian (dune) sands and alluvial deposits.

Below this are consolidated Tertiary sedimentary rocks: chalky limestones, mudstones and shales.

The lower parts of the Iullemeden Basin sequence are rocks of Cretaceous age, including: argillaceous siltstones and clays of Upper Cretaceous age; marine and lagoonal limestones, dolomitic limestones and sandstones of Cenomanian to Turonian age; coarse grained sandstones of Middle to Upper Cretaceous age; and sandstones and mudstones of Continental Terminal/Continental Intercalaire type.

Mesozoic-Palaeozoic Cambrian-Cretaceous Older sedimentary rocks crop out most on the northeast of the country, and in parts of the north, adjacent to Precambrian basement. These rocks include sandstones and siltstones of Triassic and Jurassic age; Carboniferous calcareous sandstones; Devonian argillaceous sandstones; and Ordovician sandstones and limestones.
Igneous - largely volcanic
Basement
Precambrian Plutonic grantitic and gneissose and undifferentiated crystalline metamorphic rocks.

Hydrogeology

This section provides a summary of the hydrogeology of the main aquifers in Niger. More information is available in the report UN (1988) (see References section, below).

The most extensive and productive aquifers of Niger are sedimentary formations known as the Continental Terminal and Continental Intercalaire, across much of the west (the Iullemeden Basin) and east (the Chad Basin) of the country. Weathered Precambrian crystalline basement aquifers also play an important role in the supply of water to rural centres, particularly those of Liptako and Damagaram-Mounio. Other significant aquifers are the Quaternary and Tertiary aquifers in the Lake Chad basin and the Agadez sandstone aquifer.

The hydrogeology map shows a simplified overview of the type and productivity of the main aquifers at a national scale (see the Hydrogeology map resource page for more details).

Hydrogeology of Niger at 1:5 million scale. For more information on how the map was developed see the Hydrogeology map resource page

.

Unconsolidated

Named Aquifers Period General Description Water quality
Alluvium, aeolian deposits Quaternary Where thick enough and dominated by sand and/or gravel, can be highly permeable with high storage potential. Alluvial deposits in valleys typically have shallow water tables and can form productive local aquifers. Aeolian deposits on plateaus can be dry.

Sedimentary - Intergranular Flow

Named Aquifers Period General Description Water quality
Chad Basin (Chad Formation) Quaternary Overall, dominated by loosely consolidated sands with significant permeability, forming a highly productive aquifer. Some areas are dominated by low permeability clays. Where clays are interbedded with sands, it forms a multilayered aquifer, sometimes artesian.

Surface layers recharged by direct rainfall infiltration; deeper layers have more restricted recharge.

Sedimentary - Intergranular & Fracture Flow

Named Aquifers Period General Description Water quality
Chad Basin (Continental Terminal, Cretaceous-Tertiary undifferentiated) Tertiary Overall, dominated by sandstones with significant permeability, but some areas dominated by low permeability siltstones and clays. Where clays are interbedded with sandstones, it forms a multilayered aquifer, sometimes artesian.

Surface layers recharged by direct rainfall infiltration; deeper layers have more restricted recharge.

Iullemeden (Niger) Basin (largely Continental Terminal, Continental Intercalaire) Cretaceous Sandstones, often coarse grained, and clays, limestones and silts. Unconfined in its eastern part, becoming confined towards the west below younger clays, with artesian conditions found especially in deep valleys. The Tegama sandstones form a particularly productive aquifer unit, about 500 m thick, but buried beneath about 500 m of younger cover. Low direct recharge to unconfined areas because of low rainfall.
Palaeozoic-Mesozoic sedimentary Ordovician - Jurassic Shallower, younger sandstones tend to show more intergranular flow; older, deeper sandstones and limestones tend to be dominated by fracture flow. Aquifers can be very deep - e.g. an Ordovician aquifer at more than 800 m deep.

Shallower aquifers typically form unconfined aquifer, with recharge from direct rainfall infiltration and from infilration of ephemeral river flow. Deeper aquifers are often confined, and artesian - e.g., the Carboniferous Farazekat sandstone aquifer has artesian flows of between 3 and 30 m³/hour. Deeper aquifers have relatively low recharge.

Groundwater in deeper aquifers can be highly mineralised.


Basement

Named Aquifers Period General Description Water quality
Basement Precambrian Discontinuous, low productivity aquifers controlled by the thickness and nature of weathering (regolith) and the presence of deeper fractures. Where weathered products are dominated by argillaceous material, yields are particularly low.

Groundwater Status

Niger has vast quantities of groundwater stored in deep sedimentary aquifers, much of which is likely to be ancient 'fossil' water that is not actively recharged because modern rainfall is so low. Shallower aquifers, particularly alluvial aquifers in valleys and local weathered (regolith) aquifers in basement, store much smaller amounts of groundwater, but are recharged annually by seasonal rainfall, on which they rely very heavily. In 1995, OSS estimated that Niger used less than 10% of its total groundwater resources; by 2003, this was estimated at 20% (Conseil National de l'Environnement Pour un Developpement Durable).

Some of Niger's groundwater is highly mineralised, related to high evaporation (in shallow aquifers) and/or to age and dissolution of aquifer minerals; however, this is not recognised as a widespread problem (UNICEF 2010). Borehole databases indicate that fresh groundwater occurs across the southern region; there is not enough information for other areas to assess the situation (UNICEF 2010). There are also known local problems of bacterial and nitrate contamination, related to human and animal waste disposal (UNICEF 2010).

Groundwater use and management

Groundwater use

Groundwater is a vital resource in Niger: used for rural drinking water supplies across the country; for piped urban water supplies in some areas, such as Niamey; and for agriculture, in particular irrigation.

In rural areas, groundwater is abstracted both from unimproved hand dug wells, and from improved hand dug wells and drilled boreholes.

FAO Aquastat reports (2005) that groundwater is the main source of irrigation water for most small farmer who practise irrigation, mainly abstracted from hand dug wells, and mainly applied by manual watering. A minority of small farmers use drilled boreholes. In total across Niger (data from FAO Aquastat, 2005), 64% of irrigation water was from hand dug wells and 5% from boreholes.

However, most (over 90%) large private or government-owned irrigation schemes use surface water.

Groundwater management and monitoring

A recent German Development Cooperation project, the Integrated Water Resources Management Programme, is providing advice to the Niger Basin Authority on groundwater protection. Project work has included the collection and assessment of groundwater data and maps in the Niger basin in order to develop a groundwater database, and to form the basis for future development of a basin hydrogeological map and groundwater modelling. The project also initiated groundwater level monitoring using existing boreholes, using collected data to create groundwater level contour maps for aquifers around Niamay (Menge 2013, Vassolo et al. 2015).

Information on water boreholes and hand dug wells is stored in at least two databases, one for the central region, and one that in theory covers the whole country, although there is little groundwater source data for the north and east of Niger. Of a total of more than 24,000 wells and boreholes identified by the Ministry of Water, a UNICEF study (2010) identified some 11,000 for which some information was available. Many of these, but not all, had information on borehole rest (static) water level, but none had geological log or water quality information.

Transboundary aquifers

The Niger Basin Authority (NBA) was established in 1980, with nine member states, and is based in Niamey. It has been engaged in transboundary surface water management for many years, but has not engaged extensively in groundwater management. A recent German Development Cooperation project, the Integrated Water Resources Management Programme is providing advice to the Niger Basin Authority on groundwater protection (see Groundwater management section, above).

The Iullemeden aquifer system (SAI), shared by Mali, Niger and Nigeria, includes two major sedimentary aquifers: the Continental Intercalaire and the Continental Terminal. It covers an area of ​​approximately 500 000 sq km, and is the main source of sustainable water for the vast majority of the populations of this region. The Sahel and Sahara Observatory (OSS) initiated and implemented the SAI project between Niger, Mali and Nigeria, and set up joint a consultation structure in 2008.

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 Niger. Most of these, and others, can also be accessed through the Africa Groundwater Literature Archive.

Chippaux JP, Houssier S, Gross P, Bouvier C and Brissaud F. 2002. Pollution of the groundwater in the city of Niamey, Niger. Bull Soc Pathol Exot. 95(2), 119-23.

Descloitres M, Chalikakis K, Legchenkoa A, Moussa, Genthon P, Favreaud G, Le Coz M, Boucher M et Oï M. 2013. Investigation of groundwater resources in the Komadugu Yobe Valley (Lake Chad Basin, Niger) using MRS and TDEM methods. Journal of African Earth Sciences 87, 71-85.

Favreau G, Leduc C, Seidel JL, Ousmane SD and Mariotti ANDRÉ. 2003. Land clearance and nitrate-rich groundwater in a Sahelian aquifer, Niger. International Association of Hydrological Sciences 278, 163-167.

Favreau G, Cappelaere B, Massuel S, Leblanc M, Boucher M, Boulain N and Leduc C. 2009. Land clearing, climate variability, and water resources increase in semiarid southwest Niger: A review. Water Resources Research, 45(7).

Leblanc MJ, Favreau G, Massuel S, Tweed SO, Loireau M and Cappelaere B. 2008. Land clearance and hydrological change in the Sahel: SW Niger. Global and Planetary Change, 61(3), 135-150.

Menge S. 2013. Campagne de mesure des eaux souterraines dans la région de Niamey, Niger, 4ème trimestre 2012. Rapport de projet "Appui à l’ABN pour la Gestion des Eaux Souterraines (AGES)", elaboré par Autorité du Bassin du Fleuve Niger (ABN), Niamey et Institut Fédéral des Géosciences et des Ressources Naturelles de l’Allemagne (BGR), Hannover, 31 pp, Niamey.

MHE & BRGM. 1986. Programme d’urgence pour le renforcement de l’alimentation en eau potable des quartiers de la périphérie de Niamey (Niger).

Schlüter T. 2006. Geological Atlas of Africa.

Torou BM, Favreau G, Barbier B, Pavelic P, Illou M and Sidibé F. 2013. Constraints and opportunities for groundwater irrigation arising from hydrologic shifts in the Iullemmeden Basin, south-western Niger. Water International, 38:4, 465-479, DOI: 10.1080/02508060.2013.817042

UNICEF. 2010. Etude de faisabilité des forages manuels: identifiaction des zones potentiellement favorables. Republique du Niger Ministere de l'Eau, de l'Environnement et de la Lutte Contre Le Desertification.

United Nations. 1988. Groundwater in North and West Africa: Niger. United Nations Department of Technical Cooperation for Development and Economic Commission for Africa.

Vassolo S, Schuler P, Guero A, Rabé S, Mounkaila M and Menge S. 2015. Caractérisation des eaux souterraines de la région de Niamey, Niger.Hannover: 50 pp, Hannover.

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