北运河北京段水生态承载力研究及关键控制要素识别

Water Ecological Carrying Capacity and Identification of Key Control Factors:a Case Study of Beijing Section of North Canal

北运河水系一直存在水资源缺乏、水环境污染、水生态功能不足等问题,未来北京市副中心高标准建设的加速还会增加流域的生态环境负担.因此需明确北运河北京段水生态承载力的时空变化特征,识别其关键控制要素,提升水生态承载力以满足区域发展需求.本文从水资源、水环境、水生态3个方面构建区域水生态承载力评价指标体系,收集1995—2018年北运河北京段的评价指标数据,运用熵权法确定指标权重,分析北运河北京段的水生态承载力状况及关键控制要素.结果表明:1995—2015年,北运河北京段整体处于超载或临界超载状态,2018年水生态承载力有所提升,达到安全承载状态;各子流域间水生态承载力差异显著,其中,位于北运河上游的沙河子流域在1995—2000年处于安全承载状态,在2005—2018年处于临界超载状态,水生态承载状态相对较好,但仍有改善的空间;1995—2018年,清河、温榆河和凉水河等子流域水生态承载状态处于超载状态,水生态承载状态相对较差,需加大水生态承载力提升力度;影响区域水生态承载力的关键要素为河岸带林草覆盖率,其次水环境质量也对水生态承载力具有重要影响.研究显示,北运河北京段水生态承载力的提升需在改善区域生态环境状况的同时加强对水资源的综合利用.

The North Canal water system has always had problems such as lack of water resources,water environmental pollution,and insufficient water ecological functions.In the future,the acceleration of the high-standard construction of the Beijing sub-center will also increase the ecological environment burden of the basin.Therefore,it is necessary to clarify the temporal and spatial characteristics of the water ecological carrying capacity in the Beijing section of the North Canal,identify its key control elements,and increase the water ecological carrying capacity to meet the needs of regional development.This paper constructed an evaluation index system for the water ecological carrying capacity of the river basin from the three aspects of water resources,water environment,and water ecology,collected the evaluation index data of the Beijing section of the North Canal from 1995 to 2018,and used the entropy weight method to determine the index weights.The water ecological carrying capacity and key control factors of the Beijing section of the North Canal were analyzed.The results showed that from 1995 to 2015,the entire Beijing section of the North Canal was overloaded or critically overloaded.In 2018,the ecological carrying capacity of the water was improved to reach a safe carrying capacity,and the ecological carrying capacity of the water differed significantly among the sub-basins.Among them,the northern part was located in the north.The Shahe River Basin upstream of the canal was in a safe carrying state during 1995-2000,and was in a critical overload state during 2005-2018.The water ecological carrying state was relatively good,but there was still room for improvement.From 1995 to 2018,the water ecological carrying capacity of Qinghe,Wenyuhe and Liangshuihe sub basins was overloaded,and the water ecological carrying capacity was relatively poor,and more efforts should be made to increase the water ecological carrying capacity.The key factor affecting the water ecological carrying capacity was the coverage rate of forest and grass in the riparian zone,and the water environmental quality also had an important impact on the water ecological carrying capacity.Studies have shown that to the improve the water ecological carrying capacity in the Beijing section of the North Canal,it is necessary to strengthen the comprehensive utilization of water resources while improving the regional ecological environment.