Impact of climate extremes on agricultural water scarcity and the spatial scale effect

Amid the escalating frequency of climate extremes, it is crucial to determine their impact on agricultural water scarcity to preserve agricultural development. Current research does not often examine how different spatial scales and compound climate extremes influence agricultural water scarcity.Using an agricultural water scarcity index(AWSI), this study examined the effects of precipitation and temperature extremes on AWSI across secondary and tertiary river basins in China from 1971 to 2010. The results indicated a marked increase in AWSI during dry years and elevated temperatures. The analysis underscores that precipitation had a greater impact on AWSI than temperature variation. In secondary basins, AWSI was about 26% higher than the long-term average during dry years, increasing to nearly 49% in exceptionally dry conditions. By comparison, in tertiary basins, the increases were 28% and 55%, respectively. In hot years, AWSI rose by about 6.8%(7.3%for tertiary basins) above the average, surging to about 19.1%(15.5% for tertiary basins) during extremely hot periods. These results show that AWSI assessment at the tertiary basin level better captured the influence of climate extremes on AWSI than assessments at the secondary basin level, which highlights the critical importance of a finer spatial scale for a more precise assessment and forecast of water scarcity within basin scales. Also, this study has highlighted the paramount urgency of implementing strategies to tackle water scarcity issues under compound extreme dry and hot conditions.Overall, this study offers an in-depth evaluation of the influence of both precipitation and temperature variation, and research scale on water scarcity,which will help formulate better water resource management strategies.