A pragmatic approach for soil erosion risk assessment within policy hierarchies

This paper presents a methodological framework for scale-specific assessment of soil erosion by water. The framework enables the definition of hierarchical, functional and modular nested reference units which result from the integrated consideration of policy, process and model hierarchies. The framework is applied on three planning levels: at first, large scale zones are designated that show a defined risk potential for soil erosion (first level: catchments and drainage areas in the German Federal State of Saxony-Anhalt, ca. 20,000 km2). By both increasing model complexity and spatio-temporal resolution of input data, the results are locally specified within these risk zones (second level: designated farms and fields in a study area of 141 km2). This is the basis for the prediction of soil erosion areas and sediment transport to hydrologic drainage networks as well as for small scale management and measure planning (third level: designated field blocks in the study area). On this level, the mitigation of soil erosion and sediment entry to the river system is demonstrated by simulating the introduction of conservation management practices, vegetation and riparian buffer strips.We used a modified version of the empirical Universal Soil Loss Equation (USLE) ABAGflux, which includes functions to better describe sedimentation and sediment transport to hydrologic drainage networks. Aggregation and statistical methods like SICOM and k means cluster analysis were applied for objective ranking and classification of the simulation results. The study aims at contributing to an improved applicability of data and methods for the assessment of soil erosion by water and soil protection on relevant planning scales. In addition, the results are considered to be important for an improved transfer of methods developed in science to their application in soil erosion risk management.