Anthropogenic activities alter drought termination

Abstract

Despite the increasing influence of human activities on water resources in our current Anthropocene era, the impacts of these activities on the duration, rate and timing of the recovery of drought events, known as the drought termination phase, remain unknown. Here, we present the first assessment of how different human activities (i.e. water abstractions, reservoirs, water transfers) affect drought termination. Six case studies in Europe were used to analyse the human influence on streamflow drought termination characteristics. For all case studies, we compared the drought and drought termination characteristics derived from a human-influenced time series of streamflow (observation data) and a naturalised time series (modelled data) for the same period. Overall, results clearly demonstrate the influence of human activities on drought terminations in all the studied catchments. Groundwater abstractions, reservoirs and mixed influences were all found to increase the average duration of drought termination, whereas water transfers into the catchment decreased drought termination duration. Results also show that average drought termination rates increased in all case studies due to the human influence. Furthermore, start and end months of the termination phase were more skewed to certain months in human-influenced data than in the naturalised situation. Future research could extend this new knowledge by looking to add further case studies and covering different human activities to gain a wider understanding on how human actions modify hydrological droughts and their recovery. Furthering this work could also help to improve the forecasting of drought recovery in the Anthropocene, which is important for informing drought management decisions.