Hydroeconomic Optimization of Integrated Water and Salinity Management in an Arid Agricultural Region

Water shortage and salinization are the main challenges confronted by irrigated agriculture in semiarid and arid regions. As one of the top-three largest irrigation districts in China, the Hetao Irrigation District faces pressing challenges to reduce irrigation water use and mitigate soil and groundwater salinization. Managing water and salinity requires understanding and analyzing not only the hydrologic and agronomic processes involved but the cropping and irrigation decision-making of farmers. With this aim, we build a hydroeconomic optimization model, which integrates the agrohydrological processes of water and salt balance in the crop root zone and underlying aquifer into economic optimization of water allocation and crop production. The positive mathematical programming method is used to calibrate the model such that it can replicate base-year observations. Model results highlight that a portfolio of interventions is necessary for alleviating soil and groundwater salinization and maintaining agricultural productivity and revenues; it is thus crucial to understand their long-term, cumulative effects for the sake of sustainable irrigated agricultural production. The model can assist decision-making for water and salinity management in the HID and offer useful insights for water and salinity management in irrigated agriculture of other arid regions in the world.