COMPLETE HYDRODYNAMIC BORDER-STRIP IRRIGATION MODEL

In this study, a hydrodynamic model is presented for simulating all th e phases of border-strip irrigation. The explicit, second-order accura te MacCormack scheme is used for solving the governing equations of su rface irrigation. In this method, the advance and recession fronts nee d not be considered explicitly and any infiltration equation can be co upled to the surface flow equations easily. The empirical Kostiakov eq uation (Model 1DKO) and the analytical Parlange equation (Model 1DPA) for infiltration are considered in this study. The implicit Parlange e quation is solved using the Newton-Raphson technique. The models are v alidated using the experimental data available in literature. The pres ent results are also compared with the earlier numerical results based on the characteristic method. A simple subgrid technique is introduce d in order to obtain a high grid resolution near the advancing front a nd at the same time achieve a minimum computational cost. This is base d on using two different grid sizes for computation An equation for th e optimum grid size ratio is presented and is validated using numerica l experimentation.