ИСТИНА

Case studies focus on predicting soil erosion rates using different Cs-137contamination levels as markers of erosion processes. This study was performed in western and central parts of the Bryansk Region with different Cs-137 contamination levels (from 7 to 2000 kBq/m2) obtained by air gamma survey, with 100 m resolution and soil classes from grey loamy soils (landscapes of the Opolje) to sandy podzol soils (landscapes of Polesje). Cs-137 patterns were investigated to estimate soil redistribution rates in different slope positions. In addition to the Cs-137 contamination, SRTM DEM parameters, such as slope angle, flow tracing, upslope area, wetness index etc. were estimated. To assess the relationship of Cs-137 with various landscape factors derived from DEM we used different statistical models, such as GLM, GAM. The SRTM DEM has a grid size of about 90 m, which is not sufficient for distributed erosion modeling at the landscape scale. The scaling problem arises because of the mismatch between SRTM DEM pixel dimension and the size of the erosion network (with width about 10-50 m) that concentrates Cs-137 and soil erosion products. To build a hydrologically correct flow tracing with resolution 25 m an original downscaling procedure was applied.