The Middle Route of the South-to-North Water Diversion Project (MRP) is an important water supply for 20 large cities and 100 counties in Northern China. However, since 2016, the growth of large filamentous algae clusters has threatened the safety of the main canal water supply and water quality. In this study, a field investigation, monitoring, and hydrodynamic simulation were performed to analyze the hydrodynamic habitat conditions in areas with vigorous algae growth and establish a relationship between the hydrodynamic habitat conditions of the main canal and the growth, distribution, and correlation of macrobenthic algae in the main canal. The results showed that: (1) algae zones in the main canal are more likely to appear along curves, and the largest algal zone was at the front of the large curved section; (2) the length of the algae growth zone is related to the flow rate; and (3) a lower flow velocity in the main canal facilitates faster growth of an algae zone. This study provides specific and effective suggestions for the key prevention and control positions, which has important guidance on improving the efficiency of algae control in the main canal.

The application of automatic control to irrigation canals is an important means of improving the efficiency of water delivery. The Middle Route Project (MRP) for South-to-North Water Transfer, the largest water transfer project in China, is currently under manual control. Given the complexity of the MRP, there is an urgent need to adopt some form of automatic control. This paper describes the application of model predictive control (MPC), a popular real time control algorithm particularly suited to the automatic control of multi-pool irrigation water delivery systems, to the MRP using a linear control model. This control system is tested in part of the MRP by means of numerical simulations. The results show that the control system can deal with both known and unknown disturbances, albeit with a degree of resonance in some short pools. However, it takes a long time for the MRP to reach a stable state under the MPC system and the calculation time for the whole MRP network would be too long to satisfy the requirements of real-time control. Suggestions are presented for the construction of an automatic control system for the MRP.

For an open channel with cascade pumping stations, the water level immediately upstream of the pumping station should be kept constant to ensure pumping stability and lining safety. In this study, a simple method was proposed to determine the control time of the pumping station to ensure a stable water level immediately upstream of the pumping station using reverse analysis. The variable discharge process and fixed water level were taken as the upstream and downstream boundaries of the one-dimensional open channel hydrodynamic model, and the discharge process of the pumping station was obtained under ideal conditions. The control time was determined by the equivalent water volume change considering the step change of the discharge of the pumping station. A case study was performed using the Jiaodong water diversion project from Songzhuang sluice to Huibu pumping station (G1–P1), and the effects of the initial discharge, variable discharge, and downstream water level on the control time were investigated. The results show that (1) the larger the initial discharge, the shorter the control time; (2) increasing the upstream discharge reduced the control time, while decreasing the upstream discharge increased the control time; (3) the control time decreased with the increase of the water depth immediately upstream of the pumping station.

This study focuses on the regulation demand of the cascade gates group water diversion project during the flow adjustment period. A multi-objective optimization regulation model was coupled with the one-dimensional hydrodynamic model and the multi-objective genetic algorithm. Gate opening was used as the decision variable to generate the local operation-oriented cascade gates group regulation scheme. This study considered the Shijiazhuang to Beijing section of the middle route of the South-to-North Water Diversion Project. The optimal operation model has a better control effect than the conventional control method, and the number of gate operations was reduced by 23.38%. The average water level deviation was less than 0.15 m when the feedforward control time of the cascade gates group water diversion project was not more than 24 h. The basic mechanism of maintaining water level stability during the short-term scheduling of the cascade gates group water diversion project makes use of the volume capacity, or the space of the channel pool adjacent to the water demand change position, in advance. The multi-objective optimal regulation model of the cascade gates group that was constructed in this study can quickly generate regulation schemes for different application scenarios.