基于GIS的长江三峡水库消落带生态类型划分及其特征

利用GIS技术,以水位高程变化、库岸坡度和小尺度地形地貌特征为依据,在数字地形图上,制作水位高程-坡度图和小尺度地形地貌图,通过图形叠加分析,对长江三峡水库消落带进行生态类型划分。结果表明:三峡水库消落带生态类型可划分为经常性水淹型(缓坡型、陡坡型)、半淹半露型(缓坡型、陡坡型)、经常性出露型(缓坡型、陡坡型)、岛屿型(常淹型、出露型)、湖盆-河口-库湾-库尾型(湖盆型、河口型、库湾型、库尾型)、峡谷型等6大类12个亚类;半淹半露型、经常性出露型和湖盆-河口-库湾-库尾型,占消落带总面积的82.2%,应以人工生态修复为主、自然恢复为辅;而经常性水淹型、岛屿型和峡谷型占17.8%,应以自然恢复为主、人工生态修复为辅。

GIS-based division of ecological types and their characteristics of water-level-fluctuating zone in the Three Gorges Reservoir of Yangtze River

By using GIS technology, and taking water level change, bank slope of reservoir, and small scale geomorphology as the environmental evaluation indicators, the water level elevation-slope and spatial geo-morphological maps of the Three Gorges Reservoir were drawn, based on the digital topographic map, and, through overlay analysis, the ecological types of water-level-fluctuating zone (WLFZ) in the Reservoir were classed. The ecological types of the WLFZ could be classified into 6 classes and 12 subclasses, including perennial submerged WLFZ (gentle slope and steep slope), periodic submerged WLFZ (gentle slope and steep slope), perennial non-submerged WLFZ (gentle slope and steep slope), island WLFZ (submerged and non-submerged), lake basin-estuary-reservoir bay-reservoir tail WLFZ (lake basin, estuary, bay, and reservoir tail), and valley WLFZ. The periodic submerged WLFZ, perennial non-submerged WLFZ, and lake basin-estuary-reservoir bay-reservoir tail WLFZ together accounted for 82.2% of the entire WLFZ area, indicating that the three main ecological types should be artificial ecological restoration-based and supplemented by natural recovery, while the perennial submerged WLFZ, island WLFZ, and valley WLFZ accounted for 17.8% of the entire WLFZ area, which should be natural recovery-based and supplemented by artificial ecological restoration.