Self‐Adaptive Control of Surface Irrigation Advance

Abstract

The controllability of surface irrigation advance is examined by analytical means and numerical tests based on the linearized zero‐inertia model. First, the inflow hydrograph is proved to be identifiable from advance data. Then, it is shown that it is possible to control the advance rate by adjustment of the inflow rate. Field parameter heterogeneities are automatically taken into account, so a predetermined advance trajectory is obtained under arbitrary field conditions. The model utilizes a tentative time increment, during which a trial value for inflow is adopted. The resulting wave advance is simulated by the zero‐inertia model. Discrepancies between the actual and desired advance rate are then used to construct an objective function, whose minimization leads to a correction of the inflow rate for the next time increment of inflow. Finally, examples of self‐adaptive control are presented, in which an irrigation stream is led into a field of unknown parameters. The model uses real‐time information for the identification of the parameters and simultaneous control of the inflow rate to achieve a desired advance rate.