Assessment of Water Resources Carrying Capacity in Watersheds Using a Combined Simulation and Indicator-Based Approach:Case Study: Maharlo Catchment, Iran

Abstract

 Water Resources Carrying Capacity [WRCC] originates from the broader ecological notion of carrying capacity within natural resource management. This study refines and applies the WRCC concept by integrating simulation modeling, indicator-based evaluation, and a pressure–support framework to deliver a comprehensive assessment of water sustainability. A novel evaluation framework was proposed to address shortcomings in existing methods, particularly the limited consideration of environmental health and the substitutability of assessment indicators. This integrated approach was applied to the Maharlo catchment in southern Iran from 2003 to 2023. For a more nuanced understanding, the study period was segmented into three phases: 2003–2009, 2010–2017, and 2018–2023, with evaluations performed on annual and multi-year scales. Results indicate that water usage remained within the carrying capacity only during the first phase. The second and third phases witnessed increasing water resource stress. According to standardized evaluation criteria, WRCC and environmental health declined by one level in the latter periods, reaching their lowest levels by the final phase. The pressure–support analysis further illustrates a consistent rise in stress levels on water resources, coupled with a diminishing capacity for support. These outcomes suggest that regional development policies have prioritized rapid economic expansion over environmental constraints. Given the strong consistency between the model outputs and observed field conditions, the proposed framework can serve as a practical tool for evaluating water management policies in other similar watershed contexts.