Expected climate change impacts on surface water bodies in Lithuania

The study evaluated climate change impact on water flows and nutrient loads to surface water bodies in Lithuania by applying the SWAT model. Seven RCM and GCM combinations were selected and RCP4.5 and RCP8.5 climate change representative concentration pathways were selected for the study. The study concluded that an annual and winter increase in most river water flows are expected. The change will be driven by rising precipitation, mainly in the regions where it is already high. Less snow would result in less surface runoff, substituted by increased lateral and groundwater flows because of more water percolating through the soils. As a result, water flows could be expected to increase by 9.7% for RCP4.5 and by 35.4% for the RCP8.5 climate scenario by the end-century. Whereas sediment transport and phosphorus loads would tend to decline a little bit (median results are -11.4% and -5.6% respectively for the RCP4.5 scenario, -13.3% and -7.4% for the RCP8.5 by the end of century). Conversely, temperature driven nutrient mineralization and increased leaching are expected to cause a significant increase in nitrogen loads (by 23.1% for the RCP4.5 scenario and by 64.4% for the RCP8.5 by the end of century). Overall, it could be concluded that climate change related hydrometeorological and water quality changes were found to be the most profound for the end-century RCP8.5 climate change scenario.