Individual and combined impacts of future land-use and climate conditions on extreme hydrological events in a representative basin of the Yangtze River Delta, China

Abstract

Land use/cover changes (LUCC) as well as climate change have the potential to significantly alter the characteristics of extreme hydrological events under changing environments. This study evaluates the individual and combined impacts that LUCC and climate change have on extreme hydrological events using Soil and Water Assessment Tool (SWAT) applied in the Xitiaoxi River Basin (XRB). Two future land-use conditions, projected by CA-Markov model, and 21 climate scenarios, downscaled from three general circulation models, are considered. The results show that urban area would expand dramatically from 4.4% to 12.63%, which mainly occupy the forest-grass and agriculture land. The LUCC will decrease low flow index as well as increase high flow index, annual maximum 1-day and 5-day streamflow. Extreme precipitation indices all exhibit trends toward an increase in future occurrence. Furthermore, in testing the response of extreme hydrological events to climate change, most extreme hydrological indices are predicted to become greater than they were throughout the 1970s. The combined effects of LUCC and climate change would increase all extreme hydrological indices. Moreover, the climate change would contribute >50% of these hydrological impacts. These findings indicate that the XRB will experience more severe extreme hydrological events in both flooding and drought due to climate and land-use change. It is advised that disaster mitigation measures must be updated accordingly to respond to this changing situation.