Comprehensive evaluation of water resources sustainability in Sistan and Baluchestan, Iran: A TOPSIS-Cloud-Bayesian approach

Study region: This study focuses on Sistan and Baluchestan Province, located in the southeast of Iran, a hyper-arid region characterized by water scarcity, wetland degradation, and high dependency on transboundary water sources, particularly the Helmand River. Study focus: The primary aim of this study is to assess the Water Resources Carrying Capacity (WRCC) in the province, considering various socio-economic, hydrological, agricultural, and ecological factors. A hybrid framework combining the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), Forward Cloud Model (FCM), and Bayesian Networks (BN) was developed to evaluate WRCC across four regional clusters: Sistan Plain, Urban Centers, Coastal Areas, and Rural Baluchestan. Forty indicators were employed, weighted through the Analytic Hierarchy Process (AHP) and Entropy method. The analysis spans the period from 2010 to 2023, highlighting critical vulnerabilities in certain regions and offering an integrated perspective on water management. New hydrological insights for the region: The findings reveal a declining WRCC trend over the past decade, with rural Baluchestan and Sistan Plain showing critical vulnerabilities due to low precipitation and high dependency on the Helmand River. Coastal Areas demonstrate relative resilience due to advanced infrastructure, while Urban Centers face moderate constraints due to over-extraction of groundwater. The study emphasizes the critical role of transboundary water governance, especially the reduction in Helmand River inflows, and identifies key challenges such as climatic conditions and infrastructural limitations. Tailored strategies, including securing bilateral water agreements, improving irrigation efficiency, and promoting water harvesting, are essential to ensure sustainable water management and enhance regional resilience in line with Sustainable Development Goal 6.