Numerical simulation and control mode of soil water and salt movement in arid salinization region

In arid oases irrigation areas, soil secondary salination is one of the main problems leading to land desertification, so as to imperil the soil quality, growing of crops and agricultural production, even leading to abandonment of agricultural soils. Most salinization processes of salt accumulation in irrigated lands are largely determined by the salinity of the irrigation water and the groundwater level in the areas. So it is very crucial to control groundwater and slat for agricultural development. In this study, a two-dimensional numerical model for the soil water and salt movement was constructed, and it was calibrated and experimentally validated using data from long irrigation experiments in Yanqi basin during April 15th to December 30th in 2010 with total up to 260 days. Acceptable agreement between the model simulations and the observed data was achieved. The results show that the model is creditable. Taking wheat as an example, and considering crop's water requirement and soil salinity change, the practical irrigation program and irrigation water quantity were worked out. Based on the optimized irrigation program and irrigation water quantity, the reasonable controlled depth for groundwater and salinity regulation was determined that taking the different groundwater depths as macro-control criterion. The research can provide a theory basis for rational utilization of water resources and water-salt regulation in arid regions.