Hydrologic effects of climate change in a sub-basin of the Western Bug River, Western Ukraine

Today, integrated water resources management (IWRM) is an important approach for sustainable management and protection of catchment areas. One of the core challenges for a successful IWRM program is the assessment of climate change impacts on the quantity and quality of water resources as well as related socioeconomic sectors. In this context, the climate impact on the hydrology of the catchment “Inflow Reservoir Dobrotvir” situated in Western Ukraine was investigated. The results of the regional climate model CCLM (COSMO—Climate Limited-area Modeling) were used to evaluate the climate conditions for two 30-year future periods in the framework of the future emissions scenarios A2 and B1 as laid out by the IPCC. Based on the projected climatic conditions, a hydrologic impact study was conducted using the Soil Water Assessment Tool (SWAT). Signals of possible future climate and future water budgets were analyzed having the period 1961–1990 as a reference for current climatic conditions. Climatic and hydrologic indices were calculated to assess possible risks and opportunities for the water management sector. In a more generic manner, the implications of climatic changes for the sectors of agriculture, forestry, ecology, energy business and human health were examined with respective literature. Increasing temperatures, declining summer rainfalls and a decreasing climatic water balance were the primary simulated results for the period 2071–2100. These meteorological conditions lead to decreasing soil water content as well as decreasing runoff and groundwater recharge through nearly all seasons. Reduced water yields may affect the energy sector, water supply and water quality negatively. Water stress, especially in summer, might cause declining yields in agriculture and forestry. By contrast, rising temperatures will lead to an extended growing season, which represents an opportunity for higher agricultural and silvicultural yields. However, rising temperatures may also cause indirect effects such as higher risks of pest infestation and germs, which can have a negative impact on a variety of the evaluated socioeconomic sectors. In this work, the impact of possible future scenarios on climate and hydrology as well as resulting risks and opportunities have been identified to serve as a basis for further investigations.