The Assessment of the Amount of Soil Material Deposited on the Bottom of a Dry Erosive-Denudation Valley

The work presents the results of research on erosion and landform changes of a bottom of a dry erosive-accumulation valley in Elizówka in 1958, 1970 and 2016. The changes have been examined with the use of geodetic topographic surveys techniques. The research field was a 480-metres long part of the valley bottom. The topographic surveys in 1958 and 1970 were conducted with longitudinal (parallel to the bottom of the valley) and cross (every 20 metres) sections method. In 2016 the modern measuring devices were used. All the results, together with coordinates of points and historical data were converted into GIS spatial layer. The altitude values formed the input data for interpolation of rasters showing changes of the topography in three periods. Three TIN models were also developed to distinguish erosion and accumulation zones plus the quantity of eroded and accumulated material. The valley on the majority of its length has been raised and has changed from V-shaped into U-shaped. Accumulation of the soil material led to levelling the bottom. Accumulation concentrates along a flow line, while soil washout mainly at the bottom of slopes. The thickest sediment layers were observed in the lowest part. For the whole 1958–2016 period a total of 3470 m³ soil material has been deposited on the area of about 1.62 ha, while in the same time only 130 m³ has been eroded (from 0.22 ha).