基于分布流量法的长江宜昌段生态需水研究

Ecological Water Requirement in Yichang Section of the Yangtze River Based on Distribution flow Method

以流量指标的多概率密度法为基础,提出了分布流量法(DFM)、生态流量指数(DEFI)、分布流量法评价等级标准(DFGS)。以宜昌段为例,将分布流量法与传统的水文生态流量计算方法、流量评价方法及鱼类生态流量计算结果相比较,并对变异前后河流生态需水满足率和生态流量指数得分的变化进行评价。结果表明,分布流量法考虑了河流天然径流的年内、年际丰枯变化过程,减弱了极端流量事件及流量年内分布不均的影响,能够满足河流生态系统对径流的实际需求,优于传统水文方法,有较强的时空适用性,并具有一定的推广价值。应考虑年际丰、平、枯变化,以高于或接近变异前的生态流量等级和生态流量指数得分作为水资源和生态流量管理的标准。

A distribution flow method(DFM)and its ecological flow index(DEFI)and evaluation grade standard(DFGS)are proposed to study the ecological flow of rivers on the basis of Multi-probability density estimation.Taking the Yichang section of the Yangtze River as an example,The proposed DFM compared with traditional calculation method of hydrological ecological flow,method of flow evaluation,and calculation result of fish ecological flow,and the changes in river ecological flow satisfaction rate and ecological index score before and after variation are evaluated.Results show that the DFM considers the intra-and inter-annual variations in natural runoff,thereby reducing the in⁃fluence of extreme flow and uneven flow distribution during the year.The method can meet the actual runoff demand of river ecosystem,is superior to traditional hydrological method, and presents strong space-time applicability and certain application value.Inter-annual changes inwet, normal, and dry seasons should be considered, and the ecological flow level and ecological flow index scores higher or close to those be⁃fore the variation should be used as the criteria for water resources and ecological flow management.