Evaluation of the sediment delivery ratio of small watersheds in the forest-steppe and steppe regions of the Russian plain

Dependence between sediment delivery ratio (SDR) and morphometric parameters of a set of 27 previously studied small watersheds located in the central and southern parts of the Russian plain in various geomorphological conditions in the areas of active agricultural development is established. The SDR of small riversheds were determined using field methods. When comparing the SDR with individual terrain characteristics, there is no direct linear relationship between each of the parameters and SDR. The highest value of the correlation coefficient between the SDR and relief indicators of the small rivershed was obtained for the average steepness of the watershed area (r = 0.52). As one of the verified morphometric characteristics, the parameter of the planimetric form of the rivershed area (the circularity coefficient) was used. The resulting equation includes several morphometric parameters: the ratio of area and perimeter (derived from the circularity coefficient) and the amplitude of absolute heights. These parameters allow taking into account the watershed planimetric form and the landform energy potential. About half the SDR values, obtained by the equation, deviate within ±10% of the initial values. For watersheds with SDR > 50%, the calculated values are significantly different from the initial values due to the spread of data in this area. The obtained equation of SDR can be used together with land-use remote sensing data to study the dynamics of sediments redistribution in river basins.