长江流域六省(市)夏秋季生态干旱综合强度评估

Assessment of comprehensive intensity of ecological Drought in summer and autumn in six provinces(city)of Yangtze River Basin

2022年的长江流域大旱对农业、能源、生态等方面产生了严重影响。8月11日,水利部针对干旱影响最为严重的安徽省、江西省、湖北省、湖南省、重庆市和四川省启动了抗旱IV级响应,有关六省(市)生态系统受旱程度的定量评估亟待开展。鉴于此,本研究基于标准化生态缺水指数和改进的归一化差异水体指数,分别评估了干旱对六省(市)陆地和水域生态系统产生的影响,基于干旱事件特征分析研究区夏秋季生态干旱综合强度的年际变化,最后探讨了2022年生态干旱的主要原因。结果表明:(1)6月为生态干旱的起始阶段,7—9月陆地系统生态干旱严重程度和影响范围均不断增加,10—11月随着降雨量增加、植被需水量减小,干旱缓解,水域系统生态干旱不断加重并持续至11月;(2)1982—2022年六省(市)生态干旱综合强度呈波动增加态势,2022年均达到或接近历史同期的最大值,高强度区的面积占比高于历史平均水平的67.4%;(3)2022年降水和地表水偏少导致的低生态供水强度,与高温日数较长导致的高生态需水强度相叠加,引发了1982年以来最为严重的生态干旱。

The severe drought in the Yangtze River Basin since June 2022 has had a significant impact on agriculture,energy,and ecology.On August 11,the Ministry of Water Resources launched a level IV response to drought in Anhui,Jiangxi,Hubei,Hunan,Chongqing,and Sichuan provinces,which are the most severely affected areas of the Yangtze River Basin.At present,there are few studies on the quantitative assessment of ecological drought.In view of this,the standardized ecological water deficit index was constructed to evaluate the impact of drought on the terrestrial ecosystem in six provinces(city).Modified normalized water difference index was used to evaluate the its impact on aquatic ecosystem.Then,the interannual variation of comprehensive intensity of ecological drought in the study area was calculated based on the characteristics of drought events.Finally,the reason for ecological drought in 2022 was discussed.The results showed that:(1)June is the initial stage of ecological drought.From July to September,the severity and affected area of terrestrial ecological drought are increasing.As the rainfall increased and vegetation water requirements decreased from October to November,drought severity released.(2)During the period 1982 to 2022,comprehensive intensity of ecological drought in study region experienced an increasing and fluctuating trend.In 2022,the proportion of high-intensity areas reached its highest level since 1982,which was 67.4% higher than the historical average.(3)Ecological drought from June to November 2022,the most serious since 1982,was caused by the low intensity of ecological water supply and the high intensity of ecological water demand,which induced by less precipitation and surface water,and long high temperature days,respectively.