三峡库区生态屏障范围界定

Study on a method to define ecological barrier range in Three Gorges reservoir area

为有效保护三峡库区生态环境,应在库区175m淹没线以上建立生态屏障区。本文针对生态屏障的内涵及其具有的功能,提出了具体的生态屏障界定标准并建立了数学模型,提出了生态屏障建设相对适宜度。以忠县洋渡镇作为实例,利用Grid-Xinanjiang产流模型,计算研究区域内各网格单元的产流开始时间;利用网格水滴汇流模型,统计研究区各网格单元到达库区175m淹没线的汇流时间;利用收集到的地形、地貌和土地利用等资料统计研究区各单元的地形起伏、土壤质地、生态屏障投资费用等情况,在此基础上得到了洋渡镇生态屏障建设相对适宜度分布情况。通过计算缓冲区情景与高程情景下不同阈值的生态屏障平均相对适宜度变化曲线,确定了相应情景的生态屏障范围阈值;并通过对比2种阈值的生态屏障范围与适宜度的分布图,认为高程情景优于缓冲区情景。

The internal and surrounding water quality and environment in Three Gorges Area have changed significantly after construction.To effectively protect the ecological environment,an ecological buffer zone is planned to establish above the contour line at 175 meter which represents normal high water level.In this paper,a specific definition standard index named ＂relative ecological barrier construction fitness＂ of ecological barrier has been provided and the corresponding mathematical model built based on the ecological barrier theory for finalizing the best scope of ecological barriers.Taking the Yangdu town of Zhongxian county as an example,the Grid-Xinanjiang runoff generation model was used to calculate each grid cells＇ runoff start time,the grid water drop concentration model was used to statistic the convergence time of each grid cells.The undulating terrain,soil texture and ecological barrier investment costs were calculated base on the topography and land use data.By computing the average fitness curve of ecological barrier construction relative suitability index on buffer and elevation scenario,the corresponding optimal threshold value was determined.According to the distribution map of the scope of ecological barriers and index,the conclusion is that the elevation scenario is superior to the buffer one.