Sanaga River basin Cameroon

Location

latitudes 3°38’ N and 7°22’ N and longitudes 9°38’ E and 14°54’ E

Catchment size

135 000 km²

Climate

Sub-Humid to Equatoria
the seasonal rainfall variations exhibit a typical bimodal distribution with MAR values between 1600-1800 mm/a in the north and northwest, to an equatorial climate with four seasons (MAR from 1600-2500 mm/a
downstream (westwards), the climate passes progressively to an equatorial monsoon climate (2000–3000 mm/a P).

Geology

In a large part of its basin, the Sanaga River drains the South Cameroon Plateau, a vast undulating landscape locally interrupted by inselbergs with successive steps at fault traces and mostly covered by thick mature lateritic regolith mainly developed on a granitogneissic basement (Ségalen, 1967). The South Cameroon Plateau is referred to as a Miocene lower planation surface (Guillocheau et al., 2015). It is bordered to the north and west by the Cameroonian Ridge, which is composed of a succession of high plateaux and volcanic massifs. This ridge can be subdivided into two very distinct regions: the Adamawa Plateau and the Western Highlands. These topographic units are composed of a Precambrian basement (comprising 89% plutonic and metamorphic rocks), which in places is covered by recent eruptive volcanic rocks and sedimentary formations (Regnoult, 1986).

Soils are deep mature lateritic regolith (reaching up to 50m on the plateau) and hydromorphic soils in the valleys.

Topography

Sanaga River drains the South Cameroon Plateau 650–850 m a.s.l.

Vegetation/Land use

tropical rainforest
upper Nyong basin is covered by semi-deciduous forest characterized by Stertuliaceae and Ulmaceae
marsh forest and water meadows are found and raffias (Raphia montbuttorum) grow in the swampy depressed zones (Santoir and Bopda, 1995) for 150 km upstream of the Upper Nyong basin
downstream climatic transition leads to a change in vegetation cover from semi-deciduous forest to the east to littoral forest (Lophira alata) to the west, passing by evergreen forest (Caesalpinaceae)
in the whole basin, vegetation cover is significantly damaged by agroforestry, logging, and slash and burn practices; human activities include moderate industrial forestry, traditional shifting cultivation (manioc and other tubers, banana, corn, peanuts, cocoa beans and tomatoes) without significant fertilizer inputs

Context of investigation

sediment transport
isotopes
land management
catchment hydrology

Measurements/Equipment

runoff since 1960 with five stations

Links to project webpages

Indo French Cell for Water Sciences

References

Ngoupayou, J.R.N., Dzana, J.G., Kpoumie, A., Ghogomu, R.T., Takounjou, A.F., Braun, J.J., Ekodeck, G.E. (2016):Present-day sediment dynamics of the Sanaga catchment (Cameroon): from the total suspended sediment (TSS) to erosion balance. Hydrol. Sci. J., 61(6), 1080-1093, DOI: 10.1080/02626667.2014.968572.
Regard, V., Carretier, S., Boeglin, J.-L., Ngoupayou, J.-R.N., Dzana, J.-G., Bedimo, J.-P.B., Riotte, J., Braun, J.-J. (2016): Denudation rates on cratonic landscapes: comparison between suspended and dissolved fluxes, and 10Be analysis in the Nyong and Sanaga River basins, south Cameroon. Earth Surf. Process. Landforms 41, 1671–1683, DOI: 10.1002/esp.3939.