Modelling mean annual sediment yield using a distributed approach

In this paper a spatially distributed model for the calculation of sediment delivery to river channels is presented (SEDEM: SEdiment DElivery Model). The model consists of two components: (1) the calculation of a spatial patt ern of mean annual soil erosion rates in the catchment using a RUSLE (Revis ed Soil Erosion Equation) approach; and (2) the routing of the eroded sedim ent to the river channel network taking into account the transport capacity of each spatial unit. If the amount of routed sediment exceeds the local t ransport capacity, sediment deposition occurs. An existing dataset on sedim ent yield for 24 catchments in central Belgium was used to calibrate the tr ansport capacity parameters of the model. A validation of the model results shows that the sediment yield for small and medium sized catchments (10-50 00 ha) can be predicted with an average accuracy of 41 per cent. The predic ted sediment yield values with SEDEM are significantly more accurate than t he predictions using a lumped regression model. Moreover a spatially distri buted approach allows simulation of the effect of different land use scenar ios and soil conservation techniques. Copyright (C) 2001 John Wiley & Sons, Ltd.