Multi-indicator comparison in characterizing spatiotemporal patterns of water disasters and corresponding agricultural applications in the Middle-and-lower Yangtze River

Abstract

Increasing climate change exacerbates drought and flooding disasters, posing significant threats to agricultural production and crop stability. Hydrometeorological indicators are widely employed to assess water disasters, but systematic comparisons of their efficacy in capturing spatiotemporal patterns remain limited. To elucidate the performances of multi indicators across spatiotemporal scales and to reveal water disaster patterns and high-risk zones for key crops, this study introduced five convenient hydrometeorological indicators, i.e., SPI (Standardized Precipitation Index), SPEI (Standardized Precipitation Evapotranspiration Index), PA (Precipitation anomaly), CZI (China-Z Index), and SAPEI (Standardized antecedent precipitation evapotranspiration index) to reveal the spatial-temporal characteristics of drought and flooding in the Middle-and-lower Yangtze River Region (MLRYR, 28°45′N −33°25′N, 113°25′E −118°20′E) across years and the growing seasons of two critical crops. Additionally, the high-risk areas of crop drought and flooding were revealed. The results showed those the temporal trends of both drought and flooding were mostly increasing, and the significant trends of drought were much greater than that of flooding. The SPI detected the most significant trends of both drought and flooding, and the indicator consistency ratios by most indicators were only 29.6 % (drought) and 41.7 % (flooding). The spatial moving direction was “southern to northern” for heavy drought areas and “northern to the northeastern” for heavy flooding areas, and the eastern MLRYR suffered both heavy drought and flooding. The indicator consistency ratio by most indicators was less than 20 % in identifying heavy drought and flooding areas. The significantly increasing trends in rapeseed drought were numerous, while those in cotton drought were few. Heavy drought and flooding areas for cotton were mainly in the southern part, while those for rapeseed were in the western and northeastern parts. Compared with cotton, rapeseed suffered much higher drought and flooding risks, which were concentrated in western provinces. This methodology provides actionable insights for precision agriculture and targeted disaster mitigation strategies in major grain-producing regions.