Influence of ground dykes on shaping of the bottom of the dry valley in the agricultural catchment during heavy rains

Rainfalls, topographic features, type of soil and catchment management are main factors that affect the amount of soil denudation. The studies aimed to evaluate the intensity of water erosion during rainfalls as well as to assess the changes in shape of the flow line crossing ground dykes in the eroded agricultural catchment in Olszanka on Lublin Upland. Studies were carried out within loess catchment under arabie and orchards use in the years 2001-2004. After intensive rainfalls the quanti ty of erosion damages was assessed on a base of recorded erosion and deposition. The studies confirmed the influence of land use on the course of water erosion processes. High efficiency of ground dykes in retention of the eroded soil material was proved. In autumns of 2002, 2003 and 2004 the longitudinal sections of main flow line were analyzed. The amount of alluvial deposits in the valley bottom depended on erosion intensity, slope of flow line and catchment management. While in the upper part of flow line (above ground dyke 6) the increase of alluvial thickness was relatively small, the lower part characterized rather thick layer of acumulated soil material (25 cm)