ABSTRACT
A kinematic-wave model was developed to interact upon a non-linear optimization process for solving the inverse furrow irrigation problem, which consists to determine the soil water infiltration characteristics from the advance phase measurements. The model simulates the advance phase for different combinations between the Kostiakov-Lewis parameters, purposing to minimize the discrepancies between the simulated and measured advance times. This model is part of a computer program, named SIRTOM (Surface Irrigation Real-Time Optimization Model), developed for solving the inverse problem. Based on the fund inverse solution, SIRTOM predicts the irrigation system performance on a real-time basis, that is, during the irrigation event. The model's ability to solve the inverse problem was tested under different field conditions. The simulated advance fittings were performed for advance phases measured in irrigation events under continuous and variable flow conditions. As an innovation of this research, the variable flow management strategy has the purpose to change the advance trajectory, whenever it would be detected that the current trajectory will be a disaster for the irrigation system performance. The analysis showed that the simulation model developed in this research is viable in the solution of the inverse problem, since for all field conditions tested, it interacted satisfactorily upon the fitting process. It was verified that the solution for the furrow irrigation inverse problem is possible even during early stages of the advance phase, which substantially strengthens the SIRTOM program to make diagnosis of the irrigation system performance and to suggest for the irrigators alternatives for improving it in a real-time basis.
Key words:
furrow; advance; performance; irrigation management