USING THE RASTER CALCULATOR TOOL TO APPRAISE RIVERBED ELEVATION CHANGES NEARBY HYDROTECHNICAL OBJECTS ON ALLUVIAL RIVERS

Summary The paper presents the results of analyses of morphological changes of the Dnieper River bed, in a section of direct influence of the dam in Kaniv (Central Ukraine). The regulation of the Dnieper River flow with a cascade of storage reservoirs, which were built in the years 1938 to 1975. The Kaniv dam caused significant changes in its active river channel and hydrological regime. In 2015, data on the riverbed morphology was collected. Specific river depth measurements carried out with ingle beam echosouder (SBES) and then compared with archival bathymetric maps from 1962, 1981. The tests cover the active Dnieper river channel of 600 – 1500 metres in width, from dam to Zapoviednik Island river kilometre. The paper includes the results of morphometric analyses of vertical and horizontal changes of the riverbed below dam. Morphometric analyses were performed on raster files with GIS tools, including the Raster Calculator with Map Algebra algorithm. The obtained results enabled the assessment of selected morphological parameters are formed in the tested river reach.