A sustainable irrigation water management framework coupling water-salt processes simulation and uncertain optimization in an arid area

Field irrigation water management depends on interactions among crop yield, soil water/salt and groundwater/salt in arid irrigation area with shallow-saline groundwater. This paper presents a novel uncertainty simulation-optimization framework for irrigation water allocation and sustainable agricultural environment, which integrates simulation of physical processes of soil-groundwater water and salt balance into an uncertainty-based optimization model. The impacts of crop evapotranspiration, soil water and salt and groundwater levels are interactively involved in the simulation model. Uncertainties (economic and crop parameters, available water amount) presented as fuzzy boundary intervals and probability distribution functions are considered in the optimization model. This field irrigation water allocation framework emphasizes the role of field soil water and salt movement processes to decision-making of irrigation water allocation. Then, the proposed simulation-optimization framework was applied to a case study in the Hetao Irrigation District, an arid area of northwest China where soil salinity is a serious environmental problem induced by irrigation and shallow groundwater. Therefore, optimal irrigation water allocation solutions can be generated for providing decision makers with reliable decision options where the maximum system benefits resulting from sustainable agricultural production are desired. Furthermore, the results can support analysis of interrelationships among system benefits, water allocation planning and groundwater depth, soil salt content constraints. Scenario analysis (groundwater table depth (GTD) = 1, 1.5, 2, 2.5, 3 m and no groundwater exchange consideration) showed that the maximum net benefit could be [27469, 44818] Yuan with the groundwater table depth of 1.5 m. Also, the irrigation water allocation changed when the salt constraint was considered, which indicates that the results obtained by the developed framework can alleviate soil salinization to a certain degree. Therefore, this framework can provide more effective information for the irrigation water management and soil salinization control, which is meaningful for the sustainable development of irrigation agriculture.