中文摘要：

根据河流的自然和社会功能将河流流量分为环境流量与水利流量,并探讨其确定方法及计算模型。以环境流量作为河流健康表征因子,通过建立二元水循环下河流环境流量最小阈值模型,探讨了河流环境流量的预警问题,并以颍河登封河段为案例进行分析。计算结果表明：二元水循环条件下,河流环境流量是决定河流健康的主要因子,它与开发利用率、回归率、消耗率、污径比等有直接的函数关系。应用河流环境流量最小阈值模型能预警河流健康,具有广泛应用前景。

英文摘要：

Based on the natural and social functions of rivers,the river flows can be divided into environmental flow（EF） and conservancy flow（CF）,and their determination methods and calculation models are discussed.The EF is considered as the characteristic factor for river health,which is predicted by establishing its minimum threshold models in dualistic water cycle.The situation of Dengfeng reach in the Yinghe River is taken as an example to study the characteristics of enviromental flow.The results show that the EF is the main factor to determine the river health in dualistic water cycle,and there are direct functional relationships between EF and development-utilization rate,withdrawal rate,consumption rate and dilution-ratio.The minimum threshold model of EF can be applied to predict the river health.It has wide application prospect.