Evaluation of water-resource carrying capacity in Daman Irrigation District in the middle reaches of Heihe River

To assess the state of the water-resource carrying capacity and promote the rational development of water resources in the Daman Irrigation District in the middle reaches of the Heihe River, an evaluation system with 11 indicators was constructed under the “water resources-society-economy-ecology” framework. The changing trends of the water-resource carrying capacity in the irrigation district from 2014 to 2023 were evaluated using the TOPSIS model based on game theory with combined weights. The indicators constraining the water-resource carrying capacity were identified using the obstacle degree model. Finally, the coupling coordination degree among the subsystems of water-resource carrying capacity was analyzed using the improved coupling coordination degree model. The results indicate that: (1) the overall water-resource carrying capacity of the Daman Irrigation District is at level IV (mildly overloaded), showing a downward trend from 2014 to 2018 and an upward trend from 2019 to 2023. (2) The water-resource carrying capacity is constrained by the amount of water resources per unit area, the utilization coefficient of irrigation water, the per capita water resources, and the proportion of groundwater. (3) The subsystems of water-resource carrying capacity in the Daman Irrigation District are antagonistic; the overall coupling coordination degree is at the brink of imbalance. To ameliorate this situation, the Daman Irrigation District should optimize the allocation of water resources, establish a dynamic monitoring system that integrates water resources, social economy and ecology, and incorporate the index data of industrial structure into the evaluation of water-resource carrying capacity. These recommendations would improve the applicability and reliability of evaluating water-resource carrying capacities in irrigation districts.