Soil Erosion and Sediment Yield Modelling in the Pra River Basin of Ghana using the Revised Universal Soil Loss Equation (RUSLE)

Abstract

There has been an upsurge of uncontrolled land use activities in the Pra River Basin in Ghana which are likely to promote surface soil erosion into the fluvial sediment transport system of the basin. The revised universal soil loss equation (RUSLE) was integrated with Geographic Information System (GIS) to model the spatial patterns in soil erosion and sediment yield in 2008 within the catchment. Parameters of the model were formatted as raster layers and multiplied using the raster calculator module in ArcGIS to produce a soil erosion map. The concept of sediment delivery ratio (SDR) was used to determine the annual sediment yield of the catchment by integrating a raster SDR layer with that of the soil erosion map.

Predicted soil loss and sediment yield were found to be low due to good soil protective cover by vegetation and tree crops as well as a low relief of the physical landscape. Though, the elements and processes prevailing in the basin in 2008 result in low surface soil erosion and sediment yield, this condition could degenerate into very severe surface soil erosion if the current state of land degradation, particularly small scale mining (galamsey) activities are allowed to continue.

Keywords: Geographic information system; Pra River; revised universal soil loss equation; sediment delivery ratio; soil erosion modelling; sediment yield modelling