Impact of expected increase in precipitation intensities on soil loss—results of comparative model simulations

Abstract

The impact of the expected climate change on the frequency and extent of soil erosion processes is hardly assessable so far. This is mainly because available models of climate change reliably produce at best mean daily precipitation data, whereas erosion is the result of extreme but short time rainfall and runoff events, normally lasting no longer than a few hours. The frequency and intensity of these extreme rainfall events are expected to increase in some regions, which could lead to increased erosion rates. Mathematical models are able to describe erosion rates under conditions of these extreme events, however, so far prognostic meteorological data necessary for the application of these models are not available. The use of a new method for the projection of meteorological time series and their extremes using global climate simulations [ Enke, W., Spekat, A., 1997. Downscaling climate model outputs into local and regional weather elements by classification and regression. Climate Research 8, 195–207; Enke, W., 2000. Regionalisierung von Klimamodellergebnissen mittels des statistischen Verfahrens der Wetterlagenklassifikation und nachgeordneter multipler Regression für Sachsen. 5. Deutsche Klimatagung, Hamburg, 2–6. Oktober 2000; Enke, W., 2003. Regionaler Wandel im Freistaat Sachsen. AZ. 13-8802.3521/51, Im Auftrag des Sächsischen Landesamtes für Umwelt und Geologie; Enke, W., Deutschländer, Th., Schneider, F., Küchler, W., 2005. Results of five regional climate studies applying a weather pattern based downscaling method to ECHAM4 climate simulations. Meteorologische Zeitschrift 14, 247–257; Enke, W., Schneider, F., Deutschländer, Th., in press. A novel scheme to derive optimized circulation pattern classifications for downscaling the forecast purposes. Theoretical and Applied Climatology] permits for the first time an approximation of future soil loss. This research is based on simulated, high resolution data for extreme rainfall events in the period of 2031–2050, which reproduces the mean frequency, intensity and duration of future events with high precipitation intensities relevant to erosion within the investigated seasonal period from June to August. The simulations are performed for two exemplary sites in Saxony, based on the EROSION 2D model ( Schmidt, J., 1990. A mathematical model to simulate rainfall erosion, Catena, Suppl. 19), which is a process-based soil erosion model for simulating soil erosion and deposition by water on single slopes. Simulated precipitation for the 2031–2050 time period is used to model soil loss, and results are compared to soil loss based on 20 years of measured precipitation from 1981 to 2000. The simulation results allow the impacts of climate change on erosion rates to be quantified by comparing current climate with predicted, future climate. However, expected changes in land use due to changed economic conditions are not taken into account in this analysis.