三峡水库运行前后洞庭湖水资源量变化

为研究三峡水库运行前后洞庭湖水资源量变化情况，通过利用1994-2019年165个时相的多平台中高分辨率（15~30 m）卫星遥感数据，城陵矶多年日观测水位数据和洞庭湖区降水量、蒸发量等资料，采用掩膜处理、K-Means聚类分析提取水面信息，结合观测数据进行统计分析，研究了1994年以来洞庭湖水面面积与湖容变化情况.结果表明:三峡水库运行后洞庭湖年均水面面积由1 077.46 km2减少到857.13 km2，减幅达20.45%，但是2011年后当城陵矶水位大于26.34 m时水面有所增加；三峡水库对下泄量的调控在缓解洞庭湖洪涝灾害隐患的同时，也使得低枯水位提前1个月，且对洞庭湖枯水期的补给水量极其有限；三峡水库运行后洞庭湖湖容明显减小，且当城陵矶水位越高时，洞庭湖湖容减幅越大；当水位小于20 m时三峡水库运行前后两个时段的湖容逐渐接近.洞庭湖水资源量变化主要受出入湖径流影响，"四水"径流是影响洞庭湖水资源量的主要因素，"三口"径流的减少也对洞庭湖水资源量的变化起着重要作用.同时，湖区年均降水量的减少和蒸发量的增加也是引起洞庭湖水资源量减少的原因之一.研究成果为三峡工程运行后治湖思路调整、洞庭湖区水资源保护和长江流域生态修复提供了客观资料. 

Changes of Water Resources amount in Dongting Lake before and after the Operation of the Three Gorges Reservoir

In order to study the changes of water resources amount in Dongting Lake before and after the operation of the Three Gorges Reservoir, this research used 165 multi platform high-resolution (15-30 m) satellite remote sensing data of 1994-2019, combined with the daily observation water level data of Chenglingji for many years and the data of precipitation and evaporation in Dongting Lake area, the water surface information extracted by mask processing and K-means clustering analysis, studies the changes of water surface area and lake capacity of Dongting Lake since 1994. Theoperation of the Three Gorges Reservoir significantly influenced the changes of water resources in Dongting Lake. In this study, 165 multi-platform satellite data were combined with the daily hydrological and meteorological data to explore the changes of water area and lake capacity of Dongting Lake since 1994. The water surface information was extracted by using mask processing and K-means clustering analysis. Results showed that:after the operation of the Three Gorges reservoir, the annual average water surface area decreased from 1 077.46 km2 to 857.13 km2, with a decrease of 20.45% at the water level in Chenglingji was more than 26.34 m after 2011.At the same time, the regulation of the Three Gorges reservoir not only alleviated the hidden danger of the flood disaster of Dongting Lake, but also advanced the dry water level by one month. In addition, the supply water for Dongting Lake was extremely limited during low water level period. After the operation of the Three Gorges Reservoir, the lake capacity of the Dongting Lake was significantly reduced, especially the higher the water level, the greater the reduction; When the water level is less than 20 m, the lake capacity gradually approaches during the before and after operation periods of the Three Gorges Reservoir. The change of water resources of Dongting Lake is mainly affected by the inflow of the lake.The runoff of "four waters" was the main factor determining the water resources of Dongting Lake, but the reduction of runoff of "three outlets" also playedan important role. At the same time, the decrease of annual precipitation and the increase of evaporation were also the reasons for the decrease of water resources in Dongting Lake. The research results provided objective data for the adjustment of lake management ideas, the protection of water resources in Dongting Lake area and the ecological restoration of the Yangtze River basin after the operation of the Three Gorges Reservoir.