Water Resources Carrying Capacity in Arid and Semi-Arid Resource-Based Industrial Cities: Dynamic Assessment and Scenario Simulation in Baiyin, China

Arid and semi-arid resource-based industrial cities often face limited water supply, high water demand, and pollution pressure. Using Baiyin City in northwest China as a case, this study assesses water resources carrying capacity (WRCC) with an integrated analytical approach. The indicator system includes 16 indicators covering water resources, population, economy, and water environment. Combined AHP–entropy weighting is used to determine indicator weights. The cloud model is used for grade classification, and a system dynamics (SD) model is used to compare development scenarios. Historical assessment covers 2014–2023, while scenario simulations cover 2024–2035. Per capita water resources (X1), the water resources development and utilization rate (X5), and COD discharge (X15) receive the highest combined weights, accounting for 37.049% of the total weight. WRCC increased from 0.371 in 2014 to 0.635 in 2023, and the grade improved from Grade IV to Grade II, although the trend fluctuated during 2019–2021. By 2035, simulated WRCC reaches 0.705 under the water-saving scenario, 0.655 under sustainable development, 0.643 under natural development, and 0.596 under economic development. Under the scenario settings used in this study, water saving and pollution control lead to higher WRCC values than economic expansion alone.