Impact of long-term climate change on flow regime in a Mediterranean basin

Study region: Catchment in Southern Italy Study focus: The flow regime of intermittent rivers is very sensitive to anthropogenic pressures and climate change (CC). This study investigated the long-term impact of CC on the flow regime of an intermittent river system, the Celone River (S-E, Italy), under the Mediterranean climate. The trends in precipitation and temperature measured over the past century were investigated, and the flow regime was characterized by using 27 indicators of hydrological alteration. Climate projections for the future (2030-2059) were used to predict potential CC impact on the flow regime. The Soil and Water Assessment Tool (SWAT) model was run to simulate hydrology for the current and future scenarios. New hydrological insights for the region: A significant increase in temperature and a reduction in the number of days with temperatures below 0 °C was recorded from 1958 to 2012. For the future, climate model projections predicted an increase in the daily temperature and a decrease in rainfall (4-9%) as compared with the baseline (1980-2009). As a result, the model predicted reductions in the mean annual flow by up to 21% and 39% compared to the baseline and the historical period (1965-1996), respectively. It also predicted a reduction in the maximum annual flow recorded over 90 consecutive days up to 18%, and an extension of the no-flowing phase by up to 12 days.