IRRIGATION DRAINAGE DESIGN AND MANAGEMENT MODEL - VALIDATION AND APPLICATION

The Colorado State University Irrigation and Drainage (CSUID) model is a simulation model, which can be used in the design and management of conjunctive irrigation and drainage systems. It is based on the numerical implementation of a quasi-three-dimensional finite-difference model, which solves the Richards equation and the advective-dispersive transport equation for one-dimensional vertical flow and salt transport in the variably saturated zone above the water table; and it also solves the depth-averaged Boussinesq equation and two-dimensional advective-dispersive transport equation for areal flow and transport in the fully saturated zone below the water table, In this paper, the model is validated and applied. Its performance is compared to known analytical solutions of simplified problems, the performance of other numerical models, and results of reported laboratory and field experiments. Its capabilities as a design and management tool are demonstrated by considering a hypothetical field problem. It is shown that the model can be used to evaluate design and management strategies to achieve the improved performance of conjunctive irrigation and drainage systems.