Drought-flood abrupt alternation dynamics and their potential driving forces in a changing environment

Compared with a single drought or flood, drought-flood abrupt alternation (DFAA) may have more adverse impact on water resources management, crop production, and food security. However, existing studies have paid seldom attention on the evolution characteristics of DFAA in northern China, and their driving factors have not yet been fully revealed. To this end, DFAA events such as drought to flood (DTF) and flood to drought (FTD) are examined from 1960 to 2010 in the Wei River basin (WRB) located in northern China, which is the largest tributary of the Yellow River Basin. Firstly, the long-cycle drought-flood abrupt transition index (LDFAI) is defined to identify DFAA events during the flood season of WRB. Secondly, the spatiotemporal evolution characteristics and future trend variability of DFAA events are explored based on LDFAI. Finally, the driving factors of DFAA events are comprehensively evaluated using qualitative and quantitative combination framework. Results indicate that (1) the frequency of DTF events in the WRB presents a less-more-less variation pattern from southwest to northeast and shows a significant spatial difference. However, the FDT events are vice versa; (2) the flood season is dominated by FTD events in the WRB, and the upstream of the WRB and Jing River basin (JRB) are dominated by the DTF events before mutation point; (3) the four sub-regions of the WRB show oscillation changes of DTF-FDT with 35-year period, and are prone to DTF events after 2010 years; and (4) average water vapor pressure is the dominant factor of DFAA events in the WRB compared with other meteorological factors, whereas Arctic Oscillation among multiple teleconnection factors exerts strong impacts on DFAA dynamics. The findings may be significant to the early warning and prevention of flood and drought disasters in the WRB under the challenge of future climate change.

Automated summary

Compared with a single drought or flood, drought-flood abrupt alternation (DFAA) may have more adverse impact on water resources management, crop production, and food security. However, studies on the evolution characteristics of DFAA in northern China have been limited, and the driving factors have not been fully revealed. Research in the Wei River basin (WRB) shows that DTF events exhibit a less-more-less variation pattern from southwest to northeast, while FTD events show the opposite pattern. Additionally, the flood season in the WRB is dominated by FTD events, with upstream areas experiencing DTF events prior to a mutation point.