National-scale analysis of future river flow and soil moisture droughts: potential changes in drought characteristics

The potential impact of climate change on drought is of increasing concern, especially due to recent occurrences of major events across the globe. Here a national-scale grid–based hydrological model is used to investigate potential future changes in river flow and soil moisture droughts across Great Britain. The analysis uses ensembles of climate model data for four time periods (1930s, 1980s, 2030s and 2080s) under a “business-as-usual” (RCP8.5) emissions trajectory. The results show that the severity of droughts is projected to increase in the future. River flow droughts in southeastern regions are projected to increase in peak intensity and lengthen slightly, whereas peak intensities are projected to decrease for much of the rest of Britain. Droughts with the largest spatial extent across Britain are projected to increase in area for both river flow and soil moisture. More extreme droughts than previously experienced could have a significant impact on the aquatic environment as well as the availability of water for industry, agriculture and public water supply. Regional- to national-scale droughts could have implications for potential mitigation measures such as water transfer between regions. In turn, this could lead to social and economic impacts, especially as there are also likely to be future increases in demand.