Revista Internacional de Métodos Numéricos para Cálculo y Diseño en Ingeniería

When it is carried out any movement of a gate or another mechanism of control of a canal in free surface flow, an answer of the flow can take a lot of time in being noticed in the place of the canal takes place in which it was generated the necessity to increase or to reduce the irrigation demand, for example. Usually, the scheduled perturbations of the flow can be programmed for a future horizon. In this manner, the control action can also be programmed. This work, it shows a feedforward control algorithm that plans the gate trajectories when the demand at offtakes are programmed in a prediction horizon. The Hydraulic Influence Matrix (HIM) or matrix of sensibility of the hydrodynamic conditions in the canals to changes in the parameters of the gate trajectories is a tool that is shown very effective in the control of canals in open loop. The work defines the concept, it presents the form of to calculate and to compile the HIM starting from the complete equations of Saint-Venant in their characteristic form. Later on, it shows up an algorithm in that HIM is used: a feedforward controller algorithm so-called GoRoSo. Known the water demands at offtakes, the algorithm calculates the optimal gate trajectories in advance for a prediction horizon with the objective of keeping constant the water depth at gravity offtakes.