Climate change impacts on concurrences of hydrological droughts and high temperature extremes in a semi-arid river basin of China

Hydrological droughts are natural hazards with devastating impacts on different sectors, which may cause even more adverse impacts if concurring with high temperature extremes. Though many studies have evaluated changes in individual hydrological droughts and high temperature extremes, the impact of climate change on their concurrences (or compound extremes) is still lacking. In this study, we investigated changes in compound hydrological droughts and high temperature extremes (CHDHEs) for the period 1961-2016 in the Luanhe River Basin, a semi-arid basin of China. We employed the Variable Infiltration Capacity (VIC) model to simulate runoff, based on which the temporal and spatial variation of CHDHEs was investigated. Results showed that the frequency of CHDHEs increased by 160% from 1961 to 1988 to the recent period 1989-2016. At the spatial scale, a significant increase in the frequency of CHDHEs was shown over 67.37% of the study area. Temperature was shown to play a significant role in the variation of CHDHEs with an average contribution of 57.57%. Results in this study can provide valuable insights for understanding the risk of compound droughts and high temperature extremes in the Luanhe River Basin under global warming.