ИСТИНА

The latest quantitative assessment of soil losses for the entire area of the Russian Plain was undertaken in the middle of 1980th, when maps of soil losses and gully density were constructed. Modified version of USLE model and State Hydrological Institute erosion model were used for evaluation of soil losses during warm period of year and period of snow-melting respectively. Active gully heads were identified by using large scale maps combine with using aerial photographs. Land use transformation combined with climate changes and crop rotation modification during last 25-35 years lead to changes of soil erosion rates in different parts of studied area. Complex approach is applied for assessment of recent trends of sheet, rill and gully erosion in different landscape zones of study area. Investigation is undertaken in 6 selected sectors (area of each transect is about 6-10 thousand km2), uniformly distributed over the area of the Russian Plain. Changes of the different factors, including some meteorological and hydrological parameters, land use change, USLE C-factor, were determined for the period 1990-2014. A set of field methods was used for quantification of sediment redistribution rates for the key small catchments. Particular attention is given to evaluation of gully head retreat dynamic, which is evaluated for three time intervals. Contribution of each from above mention factors on erosion rate trend changes is different in the different landscape zones of the Russian Plain.