Abstract: With continuous development of hydropower on the Wu River, the regulating functions of its upstream reservoirs show great impacts on the hydrological environment and flood defense of a downstream reservoir. This paper develops mathematical models for this river and demonstrates their applications to simulation of the hydrodynamics that are influenced by the scheduling conditions of upstream reservoirs, focusing on influences of joint scheduling on the runoff and storage capacity of the Dongfeng reservoir. The results show that: 1) the inflow of Dongfeng is affected by the operation of upstream reservoirs and its seasonal variations are reduced, with the annual mean high-low inflow ratio decreasing from 5.75 to 4.22 when the upstream Yinzidu operates and further up to 1.96 when both Yinzidu and Hongjiadu are jointly operated and scheduled. 2) The pressure of flood control on Dongfeng can be relieved by running the upstream reservoirs. Its capacity increases by 14.4% and 38.7% in the above two cases respectively. Furthermore, the hydrological environment of Dongfeng can be improved by joint operation of the two cascade reservoirs upstream, thus playing a better role in flood control and power generation.