Reuse Simulation in Irrigated River Basin

Irrigation in a river basin generally implies that the drainage water from upstream schemes is reused in the downstream schemes. The processes of water and salt movement in the schemes (over the soil surface, through the soil profile, and through the substrate) are successfully modeled in other studies. In the model presented here (called RE‐USE), these processes are linked for a series of irrigation schemes along a river. The model can be run for variable conditions (agricultural, soil, hydrological, and climatological) and variable regimes (irrigation and drainage), although these conditions and regimes have to be similar for all considered schemes. Time‐dependent variables may be defined on a daily basis (e.g., for rainfall) or on a monthly basis (e.g., irrigation‐water requirements). The model is used to explore relationships between annual rainfall, irrigation efficiency, and irrigation‐induced soil salinization. The usefulness of the model in evaluating strategies for irrigation‐water management in a basin has also been demonstrated.