长江中下游地区旱涝急转演变特征及成因分析（英文）

Analysis of evolutionary characteristics and causes of drought-flood abrupt alternation in middle and lower reaches of Yangtze River Basin

摘要

【目的】受亚热带季风气候影响，长江中下游地区旱涝急转(DFAA)事件频发，严重威胁流域可持续发展。因此，准确识别和分析DFAA事件演变规律及成因，对区域制定防灾减灾策略具有重要意义。【方法】以短周期旱涝急转指数(SDFAI)作为DFAA事件识别指标，分别探讨长江中下游地区旱转涝(DTF)事件和涝转旱(FTD)事件发生频次、影响范围和强度时空特性；其次采用多尺度地理加权回归(MGWR)模型和随机森林(RF)模型量化DFAA事件的气象和大气环流驱动因子。【结果】结果表明：(1)长江中下游DTF事件和FTD事件交替出现，年最大DTF和FTD强度分别呈减小和增加趋势，发生由DTF模式向FTD模式的转变；(2)DTF和FTD事件发生次数均主要集中在22~26次，影响范围均为轻度最大，发生强度均以中度等级为主；在空间分布上，湖南西部、安徽南部及江苏南部是DTF事件频发区，湖南和湖北南部是FTD事件频发区；(3)气温(TEM)和降水(PRE)为DFAA事件的气象主导因子，作为第一和第二影响区域占比超过50%,但日照时数(SSD)有29.12%的区域为FTD的第一影响区域，厄尔尼诺-南方涛动(ENSO)和太阳黑子(Sunspot)是影响DFAA事件的主要大气环流因子。【结论】长江中下游地区DTF事件发生强度、频次和范围相较大于FTD事件，湖南、湖北中部和安徽南部是DFAA频发区，TEM和PRE是DFAA事件的气象主导因子，ENSO和Sunspot是大气环流主导因子。研究结果可为该地区DFAA事件监测及应对提供科学指导。

Abstract

[Objective] Under the influence of the subtropical monsoon climate, drought-flood abrupt alternation(DFAA) events frequently occur in the middle and lower reaches of the Yangtze River Basin(MLRYRB), posing a serious threat to the sustainable development of the river basin. Therefore, accurately identifying and analyzing the evolution patterns and causes of DFAA events is of great significance for formulating regional disaster prevention and mitigation strategies. [Methods] The short-cycle drought-flood abrupt alternation index(SDFAI) was employed as an indicator for identifying DFAA events to examine the spatiotemporal characteristics of drought-to-flood(DTF) and flood-to-drought(FTD) events in the middle and lower reaches of the Yangtze River, including their frequency, spatial extent, and intensity. Furthermore, the multiscale geographically weighted regression(MGWR) model and the random forest(RF) model were used to quantify the meteorological and atmospheric circulation factors of DFAA events. [Results] The result showed that:(1) DTF and FTD events occurred alternately, with the annual maximum intensity of DTF events showing a decreasing trend and that of FTD events showing an increasing trend, indicating a shift from DTF-dominated to FTD-dominated patterns.(2) The number of occurrences of both DTF and FTD events was primarily concentrated between 22 and 26 times, with the slight events exhibiting the broadest spatial extent and moderate-intensity events being the most frequent. Spatially, western Hunan, southern Anhui, and southern Jiangsu were DTF-prone areas, while southern Hunan and southern Hubei were more susceptible to FTD events.(3) Temperature(TRE) and precipitation(PRE) were the dominant meteorological drivers of DFAA events, serving as the primary or secondary influencing factors in more than 50% of the region. However, sunshine duration(SSD) was the primary influencing factor for FTD events in 29.12% of the region. The El Ni1o-Southern Oscillation(ENSO)and Sunspot were the major atmospheric circulation factors influencing DFAA events. [Conclusion] Compared to FTD events, DTF events exhibited greater intensity, frequency, and spatial extent in the MLRYRB. Hunan, central Hubei, and southern Anhui are regions with frequent occurrences of DFAA events. TEM and PRE are the dominant meteorological drivers of DFAA events, while the ENSO and Sunspot were the key atmospheric circulation factors. These findings can provide scientific guidance for improving the monitoring, prediction, and management of DFAA events in this region.

关键词

短周期旱涝急转指数 / 多尺度地理加权回归 / 随机森林 / 驱动因素 / 长江中下游 / 大气环流 / ENSO / 影响因素

Key words

short-cycle drought-flood abrupt alternation index / multiscale geographically weighted regression / random forest / driving factor / middle and lower reaches of Yangtze River Basin / atmospheric circulation / ENSO / influencing factors

基金资助

国家重点研发计划项目(2023YFC3209800)

湖北省自然科学基金(2022CFB554)

湖北省自然科学基金(2022CFD037)

中央级公益性科研院所基本科研业务费青年科学家培育项目(CKSF2025156/SZ)