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
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

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.