Abstract

Representative bed material samples were taken from the gauging sites located on two rivers, Samaru River and Goruba River, in the Kubanni Watershed for sieve analysis to obtain the grain size distribution of the bed materials. The analyses of the grain size distribution showed that the bed load accounted for 7% of the total suspended sediment load of 19,039,450 kg/annum in the Kubanni Watershed. Samaru River bed material had a geometric mean particle size, D₅₀, of 0.38 mm and consequently, the river transported bed material of larger diameter than Goruba River with bed material of lesser D₅₀ of 0.30 mm. It is recommended that 7% of the total suspended load should be used as bed load estimate for sedimentation studies in the basin and also, this simple method should be encouraged for estimating bed load transport in other basins. 

Key words: Kubanni Watershed, bed load, sediment load, sieve analyses, transport.