Supply and demand of agricultural water resources under future saline-alkali land improvement

Abstract

The reserve resources of cultivated land in China are generally limited, but the number of saline-alkali land is large and has great development potential. Due to the current single development model and high pressure on water resource consumption, it is urgent to explore diversified governance models and effective water resource management. This study selected the western Jilin Province (WJP), which is located in the concentrated distribution area of soda saline-alkali land in Northeast China. By coupling PLUS model-InVEST model-crop coefficient method, eight different scenarios were designed at the same time, and the situation of normal year and dry year was considered. The changes of agricultural water resources supply and demand (AWRSD) under different scenarios in 2040 were systematically quantified. The results showed that the utilization efficiency of saline-alkali land in WJP was improved through effective land remediation. Especially in the saline-alkali land improvement scenario and the comprehensive development scenario, the area of saline-alkali land will decrease by 1188.49 km² and 1709.75 km² by 2040, respectively. Under the traditional irrigation mode, the future agricultural water resources supply (AWRS) (31.89 ×10⁸ ∼ 36.95 ×10⁸ m³) cannot meet the agricultural water resources demand (AWRD) (44.6 ×10⁸ ∼ 87.28 ×10⁸ m³), and the contradiction of water shortage in dry years is particularly prominent. Rice planting area is the key area of agricultural water resources pressure. The expansion of water-intensive crops and the changes of land use and precipitation jointly affect agricultural water resources. The study proposes to construct a deeply coupled climate-land-hydrological model to cope with the challenges of agricultural water resources under future climate change, and to achieve the synergistic goal of efficient utilization of water resources and sustainable management of saline-alkali land by constructing a governance model of 'water saving irrigation-planting structure optimization '. The research results can provide a scientific basis for future regional land use planning and water resources allocation.