ИСТИНА

INTRODUCTION Presence of the relic periglacial features (RPF) in contemporary topography and soil structure far beyond the present southern limits of the permafrost has long been established (Velichko, 1990; Andrieux et al., 2016). Recent progress in studies of the relic cryogenic microtopography has been largely achieved due to latest development of the remote sensing (RS) techniques and especially increasing availability of high-resolution satellite imagery. By present time, morphological classification of relic cryogenic features has been proposed and specifics of their zonal distribution more or less established for the Russian Plain. Significant progress has also been achieved in investigations of role of RPF in structure of modern soils (Makeev, 2009). However, potential relationships between different types of relic cryogenic features and modern hillslope processes, soil degradation processes, sediment export from hillslopes into fluvial network have so far been paid very little attention. Impact of cryogenic microtopography on spatial structure and intensity of human-accelerated soil erosion on agricultural land and its detrimental effects such as decreased soil fertility, small river degradation, reservoir siltation and water quality deterioration is not commonly taken into account for soil erosion mapping and designing soil- and water-conservation measures. Here we aim to discuss possible influence of different types of RPF on rates and patterns of modern soil erosion and deposition processes on cultivated slopes as well as sediment delivery into fluvial network. METHODS The approaches employed include analysis of the RS data, application of several independent techniques for quantitative assessment of soil redistribution on cultivated slopes and in small catchments, morphological and geochemical investigation of soil properties, georadar profiling, high-quality geodetic surveys and airborne photo by unmanned aerial vehicles (UAV). Several case study sites will be selected with various combinations of relic cryogenic feature types, zonal soil types, morphological and morphometric characteristics of cultivated slopes, density and structure of stream network. STUDY SITES AND PRELIMINARY RESULTS Four potential case study sites located in different landscape zones with different modern soil types and RPF spatial patterns (Fig. 1) have been selected so far based on availability of RS data with prominent manifestation of RPF features and existing information on modern soil redistribution rates and patterns. For two of those preliminary information on interaction between modern soil redistribution processes and is available. For the Yaroslavl Region (site 1) it has been found that modern gullies and runoff-concentrating slope depressions continue to experience influence of RPF by partly inheriting their patterns. For the Kursk Region (site 2) clear relationship between RPF types, spatial pattern of soil redistribution and sediment delivery ratios on different slopes has been observed. CONCLUSIONS AND RESEARCH PERSPECTIVES Slopes with RPF are characterized by more complex pattern and higher spatial variability of erosion and deposition and, in some cases, by higher sediment export into adjacent fluvial landforms. Modern linear erosion networks including runoff-concentrating depressions on cultivated fields and gullies in many cases inherit parts of the RPFs, though with more limited spatial extent. Acquired information is important for better understanding of relationships between modern erosion and deposition processes, contemporary spatial heterogeneity of soil structure and relic cryogenic topography formed during the Late Pleistocene glaciation. It can also be employed for optimal design of soil- and water-conservation measures for agriculture-dominated small river basins of the Western European Russia.