Water resources response to changes in temperature, rainfall and CO₂ concentration: A first approach in NW Spain

Assessment of the diverse responses of water resources to climate change and high concentrations of CO2 is crucial for the appropriate management of natural ecosystems. Despite numerous studies on the impact of climate change on different regions, it is still necessary to evaluate the impact of these changes at the local scale. In this study, the Soil and Water Assessment Tool (SWAT) model was used to evaluate the potential impact of changes in temperature, rainfall and CO2 concentration on water resources in a rural catchment in NW Spain for the periods 2031-2060 and 2069-2098, using 1981-2010 as a reference period. For the simulations we used compiled regional climate models of the ENSEMBLES project for future climate input data and two CO2 concentration scenarios (550 and 660ppm). The results showed that changes in the concentration of CO2 and climate had a significant effect on water resources. Overall, the results suggest a decrease in streamflow of 16% for the period 2031-2060 (intermediate future) and 35% by the end of the 21st century as a consequence of decreasing rainfall (2031-2060: -6%; 2069-2098: -15%) and increasing temperature (2031-2060: 1.1 ° C; 2069-2098: 2.2 °C).