Hydrogeology of Chad

From MediaWiki
Revision as of 08:15, 8 September 2015 by Beod (talk | contribs) (→‎Surface water)
Jump to navigation Jump to search

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

Most of the textual information on this page was taken from the chapter on Chad in the report‘Groundwater in North and West Africa’ (UN 1988). This information is outdated. If you have more recent information on the hydrogeology of Chad, please get in touch.

Compilers

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

Geographical Setting

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

General

Estimated Population in 2013* 12,825,314
Rural Population (% of total) (2013)* 77.8%
Total Surface Area* 1,259,200 sq km
Agricultural Land (% of total area) (2012)* 39.7%
Capital City N'Djamena
Region Central Africa
Border Countries Niger, Libya, Egypt, Sudan, Central African Republic, Cameroon, Nigeria
Annual Freshwater Withdrawal (2013)* 879.6 Million cubic metres
Annual Freshwater Withdrawal for Agriculture (2013)* 76.4%
Annual Freshwater Withdrawal for Domestic Use (2013)* 11.8%
Annual Freshwater Withdrawal for Industry (2013)* 11.8%
Rural Population with Access to Improved Water Source (2012)* 44.8%
Urban Population with Access to Improved Water Source (2012)* 71.8%

* Source: World Bank


Climate

Chad has a varied climate. In the south, rainfall is high - an annual average of 1000 to 1400 mm. In the central zone, average annual rainfall is between 700 and 1000 mm. In the north, the climate is semi-arid, with average annual rainfall between 200 and 700 mm. The far north is arid, with total annual rainfall below 500 mm. The dry northern zones have high evaporation of around 2200 to 2300 mm.

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

Southern Chad is drained by two main perennial rivers: the Chari and its largest tributuary the Logone, both of which receive flow mainly from tributaries from outside the country. The Chari river drains into Lake Chad, which is the largest surface water resource in the country. The Lake Chad basin is one of the best studied in Africa, and is shared by a number of countries, including Chad, Niger, Nigeria and Cameroon. As well as the Chari river, it is fed by two other smaller rivers flowing from Nigeria and Cameroon.

In the central and northern parts of the country, all the rivers are ephemeral, generally flowing only for a few hours after heavy rain, or at most for a few months each year.

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

Soil

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

Land cover

Land cover in Chad is largely controlled by climate. In the wetter southern zone, arable crops are and forest are widespread. In the central zone, arable crops and forest become rarer and land cover becomes dominated by grassland and savanna. In the dry north, vegetation is scarce.
Land Cover Map of Chad(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 Chad. More information is available in the report ‘Groundwater in North and West Africa: Chad’ (1988) (see References section, below).

The geology map shows a simplified version of the geology at a national scale (see the Geology resources page for more details).

Geological Environments
Key Formations Period Lithology Structure
Geological Environment 1
Name of formation1 Time period Description Structure
Geological Environment 2
Geological Environment 3


Hydrogeology

This section provides a summary of the hydrogeology of the main aquifers in Chad. More information is available in the report ‘Groundwater in North and West Africa: Chad’ (1988) (see References section, below).

The hydrogeology map 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).

 


Unconsolidated

Named Aquifers Period General Description Water quality

Sedimentary - Intergranular Flow

Named Aquifers Period General Description Water quality

Sedimentary - Intergranular & Fracture Flow

Named Aquifers Period General Description Water quality

Sedimentary - Fracture Flow

Named Aquifers Period General Description Water quality

Basement

Named Aquifers Period General Description Water quality


Groundwater Status

Groundwater quantity

Groundwater quality

Groundwater use and management

Groundwater use

Groundwater management

Groundwater monitoring

Transboundary aquifers

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 Chad.

These, and others, can be accessed through the Africa Groundwater Literature Archive

United Nations. 1988. Groundwater in North and West Africa: Chad. United Nations Department of Technical Cooperation for Development and Economic Commission for Africa, Natural Resources/Water Series No. 18, ST/TCD/5.


Return to the index pages

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