Distributed modelling of mean annual soil erosion and sediment delivery rates to surface waters

Soil erosion on arable land and on steep vineyards is a major problem in the state of Hesse (21,115 km2) in central Germany. The aim of a joint study between the Research Centre Jülich and the Hessian Agency for the Environment and Geology was to identify parcels which are severely affected by water erosion and to identify areas at risk for sediment input to surface waters. For this purpose, the ABAG, an adaption of the USLE approach to German conditions, has been employed with the best available data sets on K-, C-, R- and LS-factors. Model results show that soil losses in Hesse vary between < 0.5 and > 15 tonnes/(ha·year). The mean loss amounts to ca. 4.3 tonnes/(ha·year). The sediment delivery ratios for 450 sub-catchments range between 0.5 and 78% with a mean of 18%. An uncertainty analysis based on Gaussian error propagation and Monte Carlo simulation showed that the uncertainty of model results induced by input data is ± 1.7 tonnes/(ha·year) or ± 34%. The model results are employed for further use in a soil erosion atlas and internet-based soil data viewer.