Geography:
The
Gambia is situated
in the Sahelian zone on
 the West Coast of Africa. It is
one of the smallest
countries in Africa (the smallest being Seychelles archipelago) and has a total area of 11,300 square km, of which about
20 percent is described as wetland. The river runs from east
to west, dividing the country in two strips of land 25 to 50 km wide
and about 300 km long.
The country has a total boundary length of 820
km (510 mi), of which 80 km (50 mi) is coastline. The
River Gambia,
the country's major waterway, rises in Guinea and follows a twisting
path for about 1,600 km (1,000 mi) to the sea.
A flat plateau of tertiary sandstone, capped with an infertile
ironstone crust, gently rises from 10- 15 m at the coast to 100 m at
400 km inland. The rest of the catchments consists of older worn
Paleozoic and Pre-Cambrian rock with a maximum height of about 1500 m
in the Fouta Djallon. Pleistocene and Holocene (Nouakchottian
transgression) exist along the coast, along the estuaries and in river
valleys.
The landscape two major geomorphologic units can be distinguished
between the uplands and the lowlands:
On the upland plateaus, weathered tropical soils are found. These
soils have low intrinsic fertility and low water retention capacity,
but their drainage conditions are good. The plateau is intersected by
watercourses flowing downwards on the lowlands. These streams have
formed narrow fluvio colluvial valleys (Wulumbangos).
The lowlands include the floodplain of the
River Gambia in the Upper
Valley, and tidal plains (Banta Faros) in the Central Valley
and Lower Valley. The soils of the lowlands are flat, fine
textured and poorly drained. In the LV potentially acid sulphate soils
occur, which can become acidic soils unless water logging is
prevented by drainage.
Water Resources:
Outside salinity risk areas (Scott Wilson Kirkpatrick, 1993),
freshwater can be found throughout The Gambia, at depths ranging from
4 to 30 mbgl (metres below ground level). In general, depths increase
with proximity to the border with Senegal. Groundwater recharge
depends on the quantity and spatial and temporal distribution of
rainfall, surface geology, and land use (Howard Humphreys and Sons,
1974; Chow, 1964). Good quality surface water within the country is
only found in the eastern third of the
River Gambia. From June to
December, freshwater availability is boosted by flows from the middle
and upper Gambia River Basin areas. Low flows from January to May are
mostly sustained by local rainfall (Njie, 2002).
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Natural Habitats:
 The main feature of the land is predominantly Guinea woodland
savannah and Sahelian scrub with
with mangroves concentrated near the estuary of the
River Gambia and along its banks
and Bolongs.
The vegetation is comprised of the Savannah type with shrub and
grass understoreys. Mangroves are found in the western half of the
country in the floodplains of the river region. The cultivable land
area is roughly 430,000 hectares, which is 38 percent of the
total area. Back in 2002 available arable land was 250,000 hectares, while 5,000 hectares were
under permanent crops.
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