The southern half of the Russian Plain comprises the southern part of the forest, forest– steppe and steppe landscape zones, and it is one of the major agricultural regions in the Russian Federation. It is characterized by a temperate continental climate with a mean annual precipitation of 400–600 mm, one third of which falls during the 5 to 6 months long cold season. The precipitation and moisture availability gradually decrease in the south–southeastern direction. In the central part of the Russian Plain, around the city of Moscow, the annual precipitation is in the range of 600–700 mm while the annual precipitation near the northern coast of the Caspian Sea on the southwest of the Russian Plain is less than 200 mm. The relief of the southern half of the Russian Plain is composed of a combination of uplands and lowlands strongly dissected by fluvial networks down to bedrock and overlain by Pleistocene loess of varying thicknesses. Loess and moraine are the parent material for local soils in the central and southern parts and in the northern part of the area, respectively. Soils types change from the north to the south, from the podzol and grey forest soils to some types of chernozem in the middle, and the chestnut soils in the south of the steppe zone. Soil erosion during snow-melt events and rainstorms occurs mostly on arable lands of the Russian Plain. Mean annual soil losses from cultivated lands are estimated by soil erosion models to vary from 1 to 3 t ha within the lowlands to 6 to 8 t ha in the uplands, with the maximum (10 t ha) predicted near the Caucasus Mountains in the Stavropolskiy Krai (Sidorchuk et al., 2006). The intensity of gully erosion has been relatively low during the last two decades; however, there were a few stages during the period of the intensification of land cultivation when it was high, in particular in the uplands. The collapse of the Soviet Union in 1991 caused a serious crisis in agriculture. Part of the arable lands were abandoned and some changes in crop rotations occurred. In addition, global warming has led to changes in the proportion of soil losses from cultivated lands during snow-melt events or rain storms. Different indicators can be used for evaluating the trends in soil erosion rates, as there is a lack of monitoring data. Indicators can be split into two groups. The first group includes hydro-meteorological and agricultural parameters, namely: recurrency of extreme rains during the warm part of the year, maximum water discharges and duration of spring floods, type of crops and/or crop rotations, and area of arable lands. The second group includes characteristics of gully retreat, and sediment deposition rate dynamics in the different sediment sinks along pathways from cultivated slopes to the river channel. Four transects were selected within different landscape zones of the southern half of the Russian Plain for evaluation of contemporary trends of erosion rates on the arable lands, based on application of different indicators (Figure 1A). Each transect crossed both upland and lowland areas of the different landscape zones, and was contained within the administrative region of Russia. Typical soil types and crop rotations were represented within each transect. Maximum reduction of the agricultural land area was observed in 2003 (Figure 1B). Later on the
In order to investigate links between basin/land-use characteristics and sediment fluxes of rivers within the Oka River basin, a database has been compiled from observations obtained at 25 gauging stations located in different parts of the basin. Relatively high correlations have been found between sediment yield from basin hillslopes and river sediment yield for: (i) rivers of the forest and northern part of forest-steppe zones (r 2 = 0.50); and (ii) rivers of forest-steppe zones (r 2 = 0.52). A linear positive relationship (r 2 = 0.71) has been found between sediment delivery ratio and weighted average gradient of river channel separately for the large river basins and small river basins of the forest zone. A negative relationship between sediment delivery ratio and forested area within basins is found separately for the small (S < 2500 km 2 ) rivers and large rivers of the Oka River basin. The influence of other factors as well as the problem of small river aggradation is also discussed.
Relationship of deposition rate on small basin bottoms with the bottom structure was studied. Morphometric anal-ysis and radioisotope method ( |,7 Cs) were used. Researches were carried out at Central Russian Upland. Empirical interrelations between the structure of small basins and the deposition rates were revealed. Basins with curved longi-tudinal profiles have an accumulative layer increasing with basin order. Basins with straightened profile are charac-terized by decreasing thickness of accumulation layer as order of basin is growing. Linear correlation between accu-mulation volumes and areas has been established: V =8175 + 48, where V - mid-annual volume of deposition on a basin bottom of any order, m 3 ; S - basin area of this order, km 1 . The correlation between sediment accumulation rate and morphometric parameters of small basins may be used for estimation of total accumulation on the bottom for the "cesium" period.
The restructuring of the lower reach of the Koiavgan Creek channel (the right bank tributary of the Djankuat River) occurred on 1 July 2015 after continuous rainfall with a total precipitation amount of 227 mm. This led to the breakthrough of the Djankuat Glacier lateral moraine. The lower reach of the creek channel was initially formed at the junction of the bedrock slopes and lateral moraine and descended sharply at the end of the moraine to a wide glacial valley of the Djankuat River. The part of the channel from the end of the moraine line to the creek’s outlet in the bottom of the glacial valley had a height difference of 125 m at a distance of about 250 m. The active landslide has been recorded in the place of future breakthrough based on interpretation of 2014 summer satellite image. The linear erosion began to form on the wall of the disruption. Thermokarst processes probably also contributed to this breakthrough. The total volume of sediment eroded during the breakthrough and for four years after is 156 500 m 3 . The breakthrough has formed the largest sediment cone 300 meters wide and more than 200 m long in the bottom of the Djankuat River valley.
'/%3e%3cpath id='b' d='M658.84 441.31c-7.618 16.446-22.845 19.271-36.164 5.995 0 0 5.354-3.783 11.086-4.826-1.075-4.574 1.13-10.902 4.235-14.324 3.258 2.227 7.804 6.689 8.96 11.874 8.03-1.04 11.883 1.282 11.883 1.282z'/%3e%3cuse xlink:href='%23b' transform='rotate(9.37 700 804)'/%3e%3cuse xlink:href='%23b' transform='rotate(18.74 700 804)'/%3e%3cpath fill='none' stroke='%23f8c300' stroke-width='16' d='M603 478a340 340 0 0 1 194 0'/%3e%3cg transform='translate(700 380)'%3e%3cg transform='translate(0 -140)'%3e%3cpath id='c' d='m0-513674 301930 929245-790463-574305h977066l-790463 574305z' transform='scale(.00005)'/%3e%3c/g%3e%3cg id='d'%3e%3cuse xlink:href='%23c' transform='translate(-70 -121.244)'/%3e%3cuse xlink:href='%23c' transform='translate(-121.244 -70)'/%3e%3cuse xlink:href='%23c' transform='translate(-140)'/%3e%3c/g%3e%3cuse xlink:href='%23d' transform='scale(-1 1)'/%3e%3c/g%3e%3c/g%3e%3c/svg%3e)
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
