Implications of model uncertainty for the mapping of hillslope-scale soil erosion predictions

An integrated modelling approach (MIRSED) which utilizes the process-based soil erosion model WEPP (Water Erosion Prediction Project) is presented for the assessment of hillslope-scale soil erosion at five sites throughout En gland and Wales. The methodology draws upon previous uncertainty analysis o f the WEPP hillslope soil erosion model by the authors to qualify model res ults within an uncertainty framework. A method for incorporating model unce rtainty from a range of sources is discussed as a first step towards using and learning from results produced through the GLUE (Generalized Likelihood Uncertainty Estimation) technique. Results are presented and compared to a vailable observed data, which illustrate that levels of uncertainty are sig nificant and must be taken into account if a meaningful understanding of ou tput from models such as WEPP is to be achieved. Furthermore, the collectio n of quality, observed data is underlined for two reasons: as an essential tool in the development of soil erosion modelling and also to allow further constraint of model uncertainty. Copyright (C) 2001 John Wiley & Sons, Ltd .