Simplified hydraulic modelling in model predictive control of flood mitigation measures along rivers

Model predictive control (MPC) is an advanced technique for controlling water resources systems over short-term prediction horizons by optimizing control trajectories of hydraulic structures. Future system states are forecasted by an internal model that simulates the system response to a set of external disturbances and control inputs. This paper deals with the design and numerical implementation of dedicated simplified hydraulic models for representing flood routing processes in MPC. We present alternatives for the numerical implementation in simulation mode as well as first-order sensitivity mode and discuss the trade-off between model accuracy and computational performance in sequential and simultaneous MPC set-ups in application to two test cases: The first one is a fictitious estuary case with little potential for simplifying the full dynamic model. The second case is an application of MPC to the control of flood detention measures along the Rhine River in Germany. Both cases show the high potential of the inertial models with a semi-implicit time integration in combination with a sequential MPC set-up.