Effects of Valve Closure Strategies on Hydraulic Transients in Long-Distance Gravitational Water Supply Systems

Terminal valve closures are the main causes of hydraulic transient pressure in long-distance gravitational water supply pipelines. Therefore, reducing the hydraulic transient pressure in water supply systems through appropriate valve closure strategies is crucial. In this study, a mathematical model for the hydraulic transients contained in gravitational water supply pipelines was established using the method of characteristics for transient flows. On the basis of an actual project, MATLAB 2025b programming was used to calculate the effects of different valve closure strategies on the hydraulic transient pressure in a water supply system under various flow rate operating conditions. The results showed that the appropriate valve closure strategy should be determined according to the high-flow-rate operating conditions of the water supply system. Although extending the valve closure time can significantly reduce the fluctuations exhibited by the hydraulic transient pressure, an excessively long closure time may compromise the control efficiency of the water supply system. Compared with the linear valve closure strategy, the two-stage valve closure strategy produces smaller changes in the hydraulic transient pressure, thus reducing the hydraulic transient pressure fluctuations caused by valve closures to a certain extent. The two-stage valve closure strategy decreases the valve closure time and therefore improves the safety and flexibility of pipeline operations. This study provides a reference for determining the optimal valve closure strategy for terminal valves in similar water supply projects.