Impact of climate change on water resource availability in a mountainous catchment: A case study of the Toplica River catchment, Serbia

Abstract

The catchment of the Toplica River, situated in an underdeveloped region of southern Serbia, is studied to examine the potential impact of climate change on the hydrologic regime of mountainous catchments. The study projects precipitation (P), air temperature (T), potential evapotranspiration (PET), and discharge (Q) in the entire catchment, as well as groundwater level (GWL) variation in the lowland part of the catchment, according to scenarios RCP4.5 and RCP8.5. Projections of P and T are based on the results of a multimodel ensemble of seven regional climate models from the EURO-CORDEX project. Runoff is simulated by a calibrated HBV-light model. The correlation between GWL and river discharge was modeled by soft computing techniques of artificial neural networks (ANN). The projections pertain to the period from 2021 to 2100. The Mann-Kendall trend test is used to check for a trend and its statistical significance, and the Mann-Whitney test to examine the statistical significance of a change in the mean ensemble median of time-series for the near future (2021-2050) and distant future (2071-2100), relative to the reference period (1971-2000). No notable changes are expected on an annual scale in the study area. However, the results show that the current non-uniformity of the monthly water distribution is growing. In the winter months at the end of the century, in RCP8.5, P and T are expected to increase, as is Q. Groundwater responds to increased river discharges by reduced depths to groundwater (increased GWL). A higher Q increases the flood risk in the winter months. In the warm season, RCP8.5 predicts a decrease in Q and increase in the depth to groundwater in the distant future. Reduced quantities of water in the warm period might have an adverse effect on drinking water supply, agriculture, hydropower, fisheries, ecology, and tourism in the study area.