Predicting spatial patterns of sediment delivery and impacts of land‐use scenarios on sediment transport in Czech catchments

Abstract

AbstractFor the Czech Republic one of the most dangerous effects of soil erosion and sediment transport processes is water quality degradation, due to secondary pollutants. The WaTEM/SEDEM model, developed at Katholic University (KU) Leuven in Belgium, was tested as a prediction tool within several different Czech catchments. WaTEM/SEDEM is a spatially distributed soil erosion model running on raster GIS basis.The Watershed of Hostivar reservoir (ca 100 km2) is examined in this study. Soil loss and sediment transport have been estimated for the present state of the land use. Terrain surveys allowed us to identify actual erosion and deposition spots within the watershed and compare these with the model prediction. From the surveys, covering as yet only one season, the spatial accuracy of the model (correspondence of erosion/sedimentation occurrence with prediction) was estimated as 56 per cent. In 32 per cent the surveyed effects were predicted wrongly and in 12 per cent the correspondence was not clear.Different scenarios of possible land use changes were applied and their effect on sediment transport and the reservoir's siltation have been determined. The scenarios describe several land‐use management alternatives. C‐factor changes (crop rotation changes) were applied to selected fields—either the fields with highest soil losses or the fields with highest sediment yields (transition fields). Affected areas were increased in five steps up to ten per cent of the catchment's area. From the scenarios it is clear that focussing on ‘transition’ fields with high sediment outflow and converting them to sediment ‘traps’ gives rise to more efficiency concerning the prevention of siltation than assessing the fields only by considering the USLE erosivity prediction. Copyright © 2009 John Wiley & Sons, Ltd.