Reservoir sedimentation and hydrological effects of land use changes-case study of the experimental Dicina river watershed

Abstract

Dams have always been a precious means of collecting, storage and managing of water resources throughout history. Today, there are about 845000 dams with a total volume of about 6000 km(3). Reservoir sedimentation is a very complex problem both worldwide and in Serbia. Natural conditions and anthropogenic activities have strong influence on sedimentation intensity and hydrological processes, which is represented at the experimental watershed of the Dicina River, in Western Serbia. Reservoir of 340000 m(3) was formed after construction of a 17 m high dam, in 1966. Sedimentation of the "Velika Dicina" reservoire was determined on the basis of a survey from October 1966 to October 2011, along longitudinal profile, 750 m upstream from the dam, with 15 cross section profiles (at a spacing of 50 m). Land use changes were analyzed on the basis of a comparison of watershed conditions in 1966 and 2012, using the CORINE methodology and the MapInfo software. Sediment yield of the area and intensity of erosion processes were estimated on the basis of the "Erosion Potential Method" (EPM). The hydrological conditions in 1966 and 2012 (after the performed Erosion and Torrent Control Works-ETCWs) were assessed on the basis of a historical overview of land use changes and their impact on computed maximal discharges. Total quantity of deposited sediment in the reservoir amounts to 18750 m(3). Intensity of sedimentation has continuously been decreasing since 2002 as the consequence of land use changes, performed ETCWs and depopulation. The values of computed maximal discharges and volumes of computed hydrographs are significantly reduced. Depopulation caused a decrease in the anthropogenic pressure on the agricultural and forest surfaces in the watershed. The realization of restoration works contributed to a decrease in the annual yield of erosive material from W-a=16007 m(3) to W-a=1930 m(3).