GIS-based rapid assessment of erosion risk in a small catchment in the wet/dry tropics of Australia

Assessing the impact of various land uses on catchment erosion processes co mmonly requires in-depth research, monitoring and field data collection. as well as the implementation of sophisticated modelling techniques. This pap er describes the evaluation of a geographic information system (GIS)-based rapid erosion assessment method, which allows the user to quickly acquire a nd evaluate existing data to assist in the planning of more detailed monito ring and modelling programmes. The rapid erosion assessment method is based on a simplified version of the revised universal soil loss equation (RUSLE ), and allows the rapid parameterization of the model from widely available land unit and elevation datasets. The rapid erosion assessment method is e valuated through the investigation of the effects of elevation data resolut ion on erosion predictions and field data validation. The use of raster dig ital elevation model (DEM)-derived data, as opposed to vector land unit rel ief data, was found to greatly improve the validity of the rapid erosion as sessment method. Field validation of the approach, involving the comparison of predicted soil loss ratios with adjusted in-stream sediment yields on a subcatchment basis, indicated that with decreasing data resolution, the re sults are increasingly overestimated for larger catchments and underestimat ed for smaller catchments. However, the rapid erosion assessment method pro ved to be a valuable tool that is highly useful as an initial step in the p lanning of more detailed erosion assessments. Copyright (C) 2001 Commonweal th of Australia.