Sediment yield of a forest river basin in Ghana

Abstract

The Pra River Basin, located in south central Ghana is a forest basin that has been engulfed by certain anthropogenic activities particularly illegal small scale mining (popularly called galamsey) and serious concerns have been raised by stakeholders within the basin of the level of pollution due to the release of sediments into the water bodies. This study was undertaken to assess sediment yield levels within the Pra Basin through field data collection to ascertain stakeholder's perceptions and suggest remedial measures to the land degradation problem in the basin.Suspended sediment concentration measurements were undertaken for 10months in selected stream discharge measuring stations within the basin by coupling dip and integrated sampling approaches. Samples were analyzed using the evaporation method. Daily mean suspended sediment concentration was calculated from which monthly and annual suspended sediment yields were derived. Suspended sediment concentration (mg/l) and sediment yield (tyr−1) of the Pra Basin were found to be very high resulting in a high annual specific suspended sediment yield (tkm−2yr−1). Illegal small scale gold mining along the rivers and alluvial gold mining within the basin were found to be the probable cause for the high sediment levels of the rivers. To promote coordinated development and sustainable management of the resources of the basin, there is the need to resource agencies in charge of regulating natural resource utilization to control land use activities particularly galamsey. This will reduce fluvial sediment concentration and sustain good water quality of the rivers and promote socio-economic development in the basin.