Abstract: Guangdong Province boasts many reservoir projects, particularly small-scale ones which contribute greatly to flood prevention and irrigation while posing adverse impacts on the eco-environment along rivers. The objective of this research is to ensure sufficient ecological flow of downstream rivers. With Maodun Reservoir in Beijiang River Basin as a case study, we calculated the ecological flow using Tennant method and determined the priorities and sequences of operative functions of the Maodun Reservoir according to the Water Law (2016) of the People’s Republic of China and other laws, and further compiled the operation chart of Maodun Reservoir. Results showed that the improved method was able to obtain the comprehensive water supply-irrigation operation chart accurately at one stroke on the premise of guaranteeing the ecological runoff. In the meantime, the improved approach avoided disadvantages from using the lower boundary line of reservoir water level in relatively abundant incoming flow conditions as a guidance to operate in dry season. Specifically, those periods with an increased water supply were removed from calculation, rendering a more reasonable water demand. In addition, by doing this, we prevented the water supply restriction curve from crossing with the damage prevention curve, thereby avoiding the inaccuracy in the operation chart while enhancing the practical value of compiling comprehensive operation scheme with chronological series method.

Key words: reservoir, ecological flow, scheduling figure, programming, Beijiang River Basin