Assessment of the Expected Runoff Change in Spain Using Climate Simulations

An assessment has been conducted of the potential effect of climate change on runoff in Spain in the 21st century. Runoff depths were calculated with a precipitation runoff model that used as input downscaled global climate model (GCM) outputs. The spatial and temporal resolution of the calculations was 1 km(2) and 1 month, respectively. The assessment consisted of comparing runoff values of the baseline period, 1961-1990, with those of three 21st century periods, 2011-2040, 2041-2070, and 2071-2100, all estimated with simulated temperature and precipitation time series. Twelve climate simulations (i.e., combinations of a GCM, a greenhouse gas emissions scenario, and a downscaling algorithm), and whose variability reflects the uncertainty over the future climate, were considered. Based on the results, a decline in runoff is to be expected throughout the country. With respect to the baseline period, and depending on the climate simulation considered, runoff depths are expected to change in the range of +1 to -22% in 2011-2040, -5 to -34% in 2041-2070, and 0 to -40% in 2071-2100. (C) 2014 American Society of Civil Engineers.