Didovets I. Assessment of climate change impact on the water runoff and flood regime of Ukrainian Rivers using the eco-hydrological model SWIM.

The dissertation is devoted to the study of the climate change impact on the water runoff of three river basins representative for different natural zones of Ukraine (Teterev, West Bug, Samara) and the flood regime of mountain rivers (Tisa and Prut) by the end of the century. The objects of the study are patterns of formation of river runoff and extreme hydrological events. The subject of the study is the assessment of river runoff and flood regime changes under climate change impact. The methodology of the research can be divided by main steps: 1) preparation and setup of the hydrological model; 2) selection and preparation of climate scenarios; 3) assessment of climate change impact on river runoff; 4) assessment of climate change on floods; 5) analysis of uncertainty. The model SWIM was prepared, calibrated and validated for the five river catchments within Ukraine. The sensitivity analysis for the basic parameters of each catchment was done. The effectiveness of river runoff modelling was estimated and compliance to world standards was shown. A number of climate scenarios based on various global and regional climatic models and using different downscaling techniques by the end of the century have been analyzed and prepared. The 7 climate scenarios (RCP 4.5 and RCP 8.5) were used for the Teteriv, Samara and Western Bug basins. For the Tisza and Prut basins were used 8 climatic scenarios (RCP 4.5 and RCP 8.5). For the assessment of changes of the river discharge and climate parameters under climate change impact in the three river catchments (Teteriv, Western Bug and Samara), the period from 1981 to 2010 was selected as the reference (according to a period of bias correction of climatic scenarios). The future period was divided into three intervals: 2011-2040, 2041-2070 and 2071-2100. Each period was compared to the reference period. Changes for the Prut and Tisza catchments were analysed just for the period from 2071 to 2100 and compared with the reference (1981-2010). Changes of climate parameters (air temperature and precipitation) in all case studies areas were analysed. Depending on the area, the average annual and monthly discharge changes, together with 25, 75, 95 and 98 quantiles changes were analysed by the end of the century.