Based on ecology and hydrodynamics, a model for evaluating the estuarine ecological water requirement for flood season was established. Fishes was chosen as estuarine aquatic ecosystems key populations, and salinity was determined as the key ecological factor based on characteristics of estuarine aquatic ecosystems. The model was tested on the data from the Zhangweixin River Estuary(ZRE) in Haihe basin. The improved entropy method was used to evaluate the priority conservation order of fishes, and Scomberomorus niphonius and Cynoglossus semilaevis was identified as the priority conservation target in the ZRE and its adjacent sea area. On this basis, the relationship between estuarine salinity and discharge was simulated by using one-dimensional flow and salinity mathematical model. Under the condition of suitable salinity of target species spawning and nursery, minimum and medium ecological flow for flood season was 10.1 and 57.5 m3/s, respectively in the ZRE. The result revealed the change law of fish habitat salinity and estuarine ecological water requirement caused by hydrodynamic characteristic changes.
