Future precipitation in a Mediterranean island and streamflow changes for a small basin using EURO-CORDEX regional climate simulations and the SWAT model

Climate change effect analysis on the hydrologic cycle is essential for the assessment of water management strategies. Climate models can provide projections of precipitation changes in the future, based on greenhouse gas emissions scenarios. In this study the EURO-CORDEX (European COordinated Regional Downscaling Experiment) climate models were first analyzed for the island of Sardinia, against observed precipitation for the historical period of 1976–2005. A Multi-Model Ensemble (ENS) was built, weighting different models based on their performance against observed precipitations. Future projections (2071–2100) were analyzed using the 8.5 RCP emissions scenario to evaluate changes in precipitations. Climate models were then used as climate forcing for the SWAT model (Soil and Water Assessment Tool), aiming to evaluate the effects of such changes on streamflow and runoff of two small catchments located in the South-West Sardinia. A general decrease of mean precipitation values, up to 25 % at yearly scale in South-West Sardinia, is expected for the future, along with an increase of extreme precipitation events. Especially in the eastern and southern areas, extreme events are projected to increase by 30%. Such changes reflect on the hydrologic cycle with a decrease of mean streamflow (ranging from −18% to −25%) and runoff (ranging from −12% to −18%), except in spring, when runoff is projected to increase by 20–30%. This study contributes to the analysis of climate change impacts in the Mediterranean, which is considered a hotspot of the global warming, enhancing the use of modeling tools to investigate possible future scenarios.