Climate change impact on the Nemunas River basin hydrology in the 21st century

Climate change is likely to alter the runoff regime and its origin in the Nemunas River basin. The changes in runoff volume, seasonality and lood regime might affect hydropower production management, the potential of a forthcoming nuclear power plant and the stability of ecosystems. The water balance model WatBal was used to estimate the changes in the Nemunas River basin hydrology during the periods 1981-2000 and 2081-2100. The monthly air temperature and precipitation projections for the 21st century were estimated using the CMIP 5 model outputs. The two most diverse representative concentration pathways, RCP2.6 and RCP8.5, were analysed in this study to evaluate the spectrum of probable changes in the Nemunas River basin hydrology. The results revealed that the hydrological response to climate change in the Nemunas River basin would be most likely related to the change in snow climate. The projected magnitude of runoff changes during winter and spring is comparable for both scenarios, but the most important distinction is the difference in the cold-season hydrological regime, and especially water supply during winter and spring. According to the climate change scenarios both rain-snow and only rain dominant hydrological regimes are probable in the Nemunas River basin at the end of the 21st century.