Sub-theme
3. Building Resilience for Disaster Prevention and Mitigation
Topic
3-4. Floodwater resource management and utilization
Body
Xijiang River is one of the longest rivers in southern China. Its downstream reaches the Pearl River Delta, one of China's most economically developed regions. Longtan Reservoir is the largest reservoir built in Xijiang River. During the dry season, the flow of Xijiang River will be increased by replenishing water downstream of the reservoir, so that salinity intrusion in the estuary area will be inhibited to ensure the safe supply of water to the urban agglomeration of the Pearl River Delta. In order to improve the utilization of floodwater resources, this paper compared the correlation between precipitation in the Xijiang river basin in different periods and water replenishment in the dry season, analyzed the filling probability of Longtan Reservoir at different stages in the flood season, and optimized the hydrological forecasting scheme of water replenishment regulation. It aims to cover the shortage of hydrological forecasting scheme for the regulation of water replenishment of the Longtan reservoir. The main conclusion that can be drawn is that there is a clear correlation between the cumulative precipitation from July to March of next year and the water replenishment of Xijiang River in the dry season; and the Longtan reservoir can be stored from dead water level to flood limited water level of 366m from May to August, but it cannot be stored from 366m to normal water level of 375m from September to October in most years since the operation of the reservoir; If the impoundment work is carried out before the dry season, the floodwater resource at the end of the flood season can be fully utilized, and the probability of full storage will be increased from 54% to 77%. The study indicates that the critical hydrological forecast period for the Longtan reservoir replenishment operation is July to October. The long-term runoff forecast is the basis for impoundment work before the dry season. And the short-term flood forecast, which is with higher prediction accuracy, should be carried out for the reservoir operation decision from July to August to avoid the reservoir water level rising too fast. If necessary, the water level of the Longtan reservoir must be lowered to ensure the safety of the reservoir by means of flood pre-discharge.