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Most studies about the automatic control of open canal irrigation systems only focus on the distant downstream water level, which ignores the fact that the offtakes may be located anywhere along the canal. Such a simplified control strategy is likely to result in uncontrollable and inefficient water delivery. Therefore, a multi-point hydraulic control method is proposed, in which a simplified Saint-Venant model is formulated to describe the hydraulic states of multiple controlled points. Then, it is underlined that the controlled points with and without the offtakes may have different control objectives. It is suggested to implement soft constraints to the downstream end when there is no offtake, meaning that moderate water level fluctuations are acceptable. Model predictive control (MPC) is applied for control tests. By comparing with the common MPC controller, where the Integrator Delay model and hard constraint are used for distant downstream water level control, the proposed MPC controller successfully improved the water level control stability before the offtakes and the water supply reliability by 91 and 69.5% under the conventional condition and by 54.9 and 27.1% under the water-deficient condition. Accordingly, the proposed multi-point hydraulic control method shows great potential for the precision irrigation of large irrigation districts .

The emergency control of Menglou~Qifang inverted siphon, which is about 72 km long, is the key to the safety of the Northern Hubei Water Transfer Project. Given the complicated layout of this project, traditional emergency control method has been challenged with the fast hydraulic transient characteristics of pressurized flow. This paper describes the application of model predictive control (MPC), a popular automatic control algorithm advanced in explicitly accounting for various constraints and optimizing control operation, in emergency condition. For the fast prediction to the pipe-canal combination system, a linear model for large-scale inverted siphon proposed by the latest research and the integrator-delay (ID) model for open canals are used. Simulation results show that the proposed MPC algorithm has promising performance on guaranteeing the safety of the project when there are sudden flow obstruction incidents of varying degrees downstream. Compared with control groups, the peak pressure can be reduced by 17.2 m by MPC under the most critical scenario, albeit with more complicated gates operations and more water release (up to 9.75 × 104 m3). Based on the linear model for long inverted siphon, this work highlights the applicability of MPC in the emergency control of large-scale pipe-canal combination system.

<p>Canal automatic control is an important tool to improve the management level of water distribution systems, while an important method to evaluate the effect is controller is using numerical simulations. The free-surface flow in such system can be modelled using the Saint-Venant equations, while the regulating gates are usually treated as inner boundaries where gate discharge formula is adopted. In the previous research, the Saint-Venant equations are normally discretized using the implicit finite difference methods because of their accuracy and simplicity. However, it is difficult to incorporate the inner boundary conditions in the computation of implicit method. To circumvent this problem, this paper presents a hybrid discretization method, which adopts the state-of-art finite volume methods at regulating gates and finite difference methods elsewhere. This new discretization method can preserve the computational speed advantage of finite difference method and capture the wave propagation near the regulating gates. Which can provide reliable evidence for the design of controllers.</p>