Evaluation of water resources carrying capacity in Ordos City based on DPSIR -TOPSIS

Ordos City is located in the arid and semi-arid region of northwestern China, where the contradiction between water resource supply and demand is particularly prominent. Assessing water resources carrying capacity (WRCC) is therefore an important basis for achieving sustainable water resource development and utilization in this region. This study constructed an evaluation indicator system by integrating the DPSIR framework based on the synergistic concept of the water resources-water environment-water ecology system. An improved CRITIC method combined with the entropy weight method was applied to determine indicator weights, thereby reducing the excessive homogenization of weights and deviations from practical conditions caused by a single weighting method. Furthermore, the TOPSIS model and obstacle degree model were employed to comprehensively evaluate and diagnose the WRCC of Ordos City. The results showed that: (1) During the study period, the WRCC of Ordos City exhibited an overall trend of “steady improvement-fluctuating adjustment”. The comprehensive evaluation score increased from 0.3871 in 2000 to 0.5605 in 2023, with the overall carrying status improving from Level IV (overloaded state) to Level III (critical state), although it did not reach Level II. All administrative units showed varying degrees of improvement in WRCC, with evaluation results gradually shifting from lower levels toward critical and weak carrying states, accompanied by evident spatial differentiation. (2) Among the five DPSIR subsystems, the Impact subsystem contributed most significantly to WRCC improvement, with its score increasing from 0.2426 to 0.8766. The Driving forces and Response subsystems showed overall increasing trends, whereas the Pressure subsystem declined from 0.7199 to 0.3327, and the State subsystem exhibited considerable fluctuations. These results indicate asynchronous evolutionary patterns among the internal components of the WRCC system. (3) The obstacle degree analysis showed that the Driving forces and Response subsystems had the highest average obstacle degrees, accounting for 32.46% and 24.29%, respectively. During the early study period, ecological water replenishment and green coverage rate were the main obstacles restricting WRCC improvement. By 2023, urbanization rate, population density, ecological flow guarantee rate, ecological water replenishment, and total water use became the major obstacle factors, with total water use remaining among the leading obstacles during 2020–2023. This study reveals the dynamic characteristics of the coexistence between overall WRCC improvement and persistent subsystem constraints in arid resource-dependent regions. It provides an analytical framework for identifying key limiting factors during WRCC evolution and offers references for water resource optimization, ecological protection, and sustainable development management in similar arid and semi-arid regions.