Analysis of water resources carrying capacity and obstacle factors in Gansu section of the Wei River basin using combined weighting TOPSIS model.

Water resource carrying capacity is an important indicator for measuring sustainable development. Given the rapid economic and social development in China today, coordinating the sustainable development of water resources, socio-economy, and eco-environment has become an urgent problem to be solved. This study takes the Gansu section of Wei River mainstream basin (GWRB) as a case study and constructs a three-dimensional WRCC evaluation system and status standards. Based on this research framework, we analyzed the trends in WRCC changes of GWRB from 2008 to 2022. Additionally, we conducted an in-depth study of the internal relationships and influencing factors within the WRCC system. The results show that the combination weighting method of multi-weight models avoids the one-sidedness of single weighting, leading to a more realistic distribution of weights. The result status standard derived from the indicator status standard prevents a disconnect between the result and the status, making the evaluation more rational and accurate. The WRCC of the GWRB increased from 0.098 (overloaded) in 2008 to 0.621 (weakly bearable) in 2022. During this period, the eco-environmental system improved from critical to bearable, while the socio-economic system improved from overloaded to weakly bearable. Due to geographical and climatic limitations, the water resource system continued to bear significant pressure and remained in overloaded state for most of the time. The key factors limiting the further improvement of WRCC in the GWRB are per capita water resources, utilization rate of water resources, COD emission per 10,000 yuan of GDP, ecological water use rate, water consumption per 10,000 GDP and agricultural water use rate. To improve the WRCC, we propose a series of targeted recommendations based on the research findings. The proposed research framework can also serve as a reference for related studies in arid and semi-arid regions.