Command Area Water Demands. I: Validation and Calibration of UCA Model

Simulation of aggregate water demands by areas commanded by canal and lateral turnouts is an important input to the operation and management of the irrigation delivery system. A computer simulation model to predict these command area water-demand functions was developed and reported by Keller in 1987. To test the validity of the model, data from an existing irrigation project in the Delta, Utah, area were used to simulate the aggregate irrigation demand of five turnouts operated on a demand basis. During the model calibration process, the influence of three important variables in the operation stage on the prediction of demand was identified using the cumulative water-demand curve. The key variables were: (1) Management-allowable depletion (MAD); (2) irrigation application uniformity (IAU); and (3) initial soil moisture (ISM).