Water Resources Evaluation in Subtropical Low-Mountain and Hilly Regions with Normal Cloud and TOPSIS Model by building four-dimensional indicator system on Hydrological Zoning

Water resources are fundamental natural assets supporting sustainable socio-economic development and ecological stability. The Taojiang River Basin, a typical subtropical hilly basin within the Poyang Lake region, features rugged terrain, high soil erosion rates, and significant conflicts between agricultural irrigation demands and flood–drought disasters. To scientifically assess the basin’s water resources carrying capacity (WRCC), this study integrates fuzzy and deterministic approaches, considering the basin’s topographical and climatic characteristics. A four-dimensional indicator system was constructed, and both the Normal Cloud Model and the TOPSIS model were applied using 2023 data on topography, climate, and land use. The results show that, under the Normal Cloud Model, the overall basin and Subregions I–III are in a “weakly bearable” state, while the TOPSIS model indicates “critical,” “weakly bearable,” “critical,” and “critical” states, respectively. The two models exhibit consistent overall evaluation trends, and indicators related to the water quantity dimension are identified as the dominant influencing factors. This study demonstrates that integrating deterministic and non-deterministic evaluation frameworks can effectively enhance the scientific robustness and accuracy of WRCC assessment. The findings provide valuable references for evaluating water resource utilization and guiding sustainable water management in subtropical low mountain and hilly regions under data-limited conditions.