Nyong River Basin Cameroon

Location

latitudes 2°48’ N and 4°32’ N and longitudes 9°54’ E and 13°30’ E

Catchment size

27 800 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

The Nyong River flows in the low-relief South Cameroon Plateau landscape and then joins the coastal plain by a series of falls corresponding to the scarp of the passive margin. The basement of the Nyong River basin is mostly silicates, composed of dominant granito-gneis (Precambrian and Panafrican in age) intermingled with less abundant mafic to ultramafic rocks from Precambrian greenstone belts (Regnoult, 1986). Soils are deep mature lateritic regolith (reaching up to 50m on the plateau) and hydromorphic soils in the valleys.

Topography

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

Braun, J.-J., Marechal, J.-C., Riotte, J., Boeglin, J.-L., Bedimo, J.-P.B., Ngoupayou, J.-R.N., Nyeck, B., Robain, H.,Sekhar, M., Audry, S., Viers, J. (2012): Elemental weathering fluxes and saprolite production rate in a Central African lateritic terrain (Nsimi, South Cameroon). Geochimica et Cosmochimica Acta, 99, 243–270, DOI: dx.doi.org/10.1016/j.gca.2012.09.024.
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.