Ecological scheduling of the middle route of south-to-north water diversion project based on a reinforcement learning model

The Middle Route of the South-to-North Water Diversion project (MRP) effectively alleviates the problem of serious shortage of water resources in North China. However, owing to the long-term operation of this project, abnormal algal proliferation has occurred in the upper reaches of the main canal, and the water diversion outlet is easily blocked by the large colonies of algae falling into the canal, which has seriously threatened the water quality and water supply safety of the canal. In light of this issue, this study coupled the reinforcement learning model with the one-dimensional hydrodynamic model of the series sluice group to build an ecological scheduling model for prevention and control of algal proliferation in the MRP. The model was applied to the canal section (approximately 300 km long, from No. G2 to No. G17) where in algae grows easily. The results show that: (1) The model can achieve the desired reciprocating adjustment of the canal water level in the process of decline stability rise within 0.8 m and stably maintain the low water level for more than 72 h; (2) during the process of ecological scheduling, the maximum drawdown of water level satisfying the safety regulation and control constraints of the MRP is 1.0 m; (3) for an ecological regulation water level drop greater than 0.3 m, it is more difficult to restore the initial water level, and the water level rise range should therefore be greater than the decrease range; (4) the constructed model exhibits high robustness. Even for an observation error level less than 0.08 m, the success rate of the model can still exceed 80%. The ecological scheduling scheme generated by the model can be used to destroy the algal habitat conditions through hydrodynamic dynamic regulation, whereby decisional support can be provided for the prevention and control of abnormal proliferation of algae in the main canal.

Automated summary

By building an ecological scheduling model, this study successfully addressed the issue of abnormal algae proliferation in the Middle Route of the South-to-North Water Diversion project, ensuring comprehensive protection of water quality and supply safety in the canal.