Variability of suspended sediment yield in the Pra River Basin, Ghana

Accurate information on catchment's sediment yield is inevitable for improved catchment and water resources management. This study assesses the levels of sediment loads in the Pra River Basin, Ghana and explores its spatial variabilities. The determination of the sediment yield involved field work and laboratory analysis. River discharges were measured using acoustic Doppler current profiler (ADCP). Suspended sediments were collected using the integrated sampler. Sediment concentration analysis was performed using evaporation method whilst the data were analysed using correlation and analysis of variance. Suspended sediment concentrations and river discharges were measured and analysed at nine hydrological stations within the basin. Results indicate that sediment yields from the basin are very high (ranging between 13.29 and 215.02 tkm(-2) yr(-1)) and differ significantly (p = 0 < 0.01) with respect to the contributing drainage basins. The rivers in the galamsey prone basins are highly polluted with sediment than the others. Variations in the catchment's sediment concentration can be attributed to the differences in the intensity of anthropogenic activities within nearby drainage basins. Higher sediment concentrations for low flows and lower concentrations for high flows were observed across the sub-basins. This variability indicates that river discharges alone is not a dominant factor for river sedimentation but rather the influence of land cover, catchment characteristics and activities. Sediment fluxes observed present better understanding of the sediment controlling factors. It is therefore important to explore how land use activities and catchment characteristic influence the variation in catchment sediment yield by incorporating them into sediment prediction models.