How soil erosion model conceptualization affects soil loss projections under climate change

JPC Eekhout and J de Vente

July 8-18, 2019

IUGG General Assembly, Montreal, Canada

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Climate change will most likely cause an increase of extreme precipitation and consequently an increase of soil erosion in many locations worldwide. Different soil erosion model concepts are used to assess the impact of climate change on soil erosion at large spatial scales, such empirical and process-based models. However, there is little knowledge of the implications of model concepts on projected soil erosion rates. Here we assessed the impact of climate change with the 3 most used soil erosion model concepts, i.e. empirical with yearly time steps (RUSLE), empirical with daily time steps (MUSLE) and process-based with daily time steps (SPHY-MMF). We applied the models to 2 contrasting Mediterranean catchments (SE Spain), where climate change is projected to significantly decrease the annual precipitation sum (Sierra de Segura) or significantly increase extreme precipitation (Guadalentin), based on the RCP8.5 climate change scenario. Depending on the model, soil erosion is projected to decrease or increase in the study area, where RUSLE projects a significant decrease, MUSLE a significant increase and MMF a significant increase in only 1 of the catchments. The differences between the model projections are inherently a result of their model concept, such as a low temporal resolution (RUSLE) and the exclusion of crucial soil erosion processes (MUSLE). To assess the impact of climate change on soil erosion, it is important to select a soil erosion model that runs at an appropriate temporal resolution and accounts for the most relevant processes that may be affected by climate change.