基于二元水循环的河流生态需水水量与水质综合评价方法——以辽河流域为例

通过考虑水的自然循环与水在人类活动影响下的循环（二元水循环）,后者包括水资源开发利用率、耗水率、污水排放浓度影响,探讨了二元水循环下河流生态需水“质”与“量”的综合评价,以区别以往仅从自然水循环（一元）出发评价河流生态需水的缺陷。建立了二元水循环下的河流生态需水的水量与水质计算方法．并确定了河流生态需水的“质”与“量”的评价标准．实现了河流生态需水水量与水质的综合评价。以辽河流域为例进行实证分析。计算了一元水循环下西辽河、东辽河、辽河干流、浑太河、东北沿黄渤海诸河等水资源分区的河流生态需水．分别占径流的39.3％、63．0％、43．9％、43．3％、43．5％,采用Tennant推荐流量及等级进行评价,结果是：除西辽河属于“中”等级外,东辽河、浑太河、辽河干流、东北沿黄诸河等均在“好”等级以上．东辽河达到“极好”等级。与之对应的二元水循环下的河流生态需水比例分别是57．5％、74．1％、60．8％、60．3％、60．4％,综合评价结果显示：从水量角度评价,西辽河不能达到生态需水“量”的标准,其余能够达标,从水质角度评价,西辽河、浑太河、辽河干流、东北沿黄诸河等均不能够达到“质”的标准。东辽河可以达标。从“量”与“质”相结合的角度评价．仅有东辽河可以达标。因此．水质状况是决定辽河流域河流生态需水是否满足生态系统需求的主要问题。

Water Quantity/Quality Combined Evaluation Method for Rivers' Water Requirements of the Instream Environmental Flow in Dualistic Water Cycle: A Case Study of Liaohe River Basin

Based on the analysis of the relationship among environmental flows of river requirements, the efficiency of water resource utilization and the consumption coefficient, and discharge concentration of waste water, the water quantity and water quality calculation method of environmental flows of river requirements in dualistic water cycle is developed, and the criteria for environmental flows of river requirements are established. Taking Liaohe River as demonstration, the environmental flows of river requirements for Xiliao River, Dongliao River, Liaohe River artery, Huntai River and northeast rivers along Huangbohai (Huanghai and Bohai seas) in unitary water cycle make up 39.3%, 63.0%, 43.9%, 43.3% and 43.5% of runoff, respectively. Evaluated according to Tennant recommended flow and grade, the results show that: except Xiliao River which is "median", the rest are all above "good", and even the Dongliao River is "very good". The corresponding proportion of environmental flows for each river in dualistic water cycle is 57.5%, 74.1%, 60.8%, 60.3% and 60.4%, respectively. The combined evaluation results show that evaluated from the angle of "quantity", except Xiliao River, the rest rivers can all achieve the "quantity" criterion of environmental flows requirements, but if evaluated from the angle of "quality", only Dongliao River can meet the "quality" standard, and by water quantity/quality combined evaluation method, only Dongliao River can achieve the criterion.