Beyond traditional water resources reliance: unlocking Pakistan’s national water harvesting potential via analysis of opportunities and risks

Global water security is increasingly threatened by climate variability, rising demand, and fluctuating transboundary inflows. This study proposes harnessing Pakistan’s largely untapped rainfall-induced runoff as a sustainable pathway to address national water scarcity. We provide the first high-resolution assessment of urgency and water harvesting potential across the most populated provinces in Pakistan. Our work integrates hydrometeorology data, physiographic conditions, and land use to develop novel indices, including water harvesting potential (WHP) and storage urgency index (SUI). Our flow severity analysis revealed increasingly frequent low-flow years at key reservoirs since 2015, underscoring the unreliability of upstream sources and compromising their role in water storage, irrigation, and hydropower generation. Concurrently, rainfall trends across different regions in Pakistan have shown significant increases since 2010, with many districts now exceeding their 95th percentile thresholds on an annual basis. Disparities in SUI and WHP are highlighted as priority intervention areas. Rahim Yar Khan, Rajanpur, Jamshoro, and Tharparkar districts were identified as top-priority areas under the SUI framework, characterized by a high physical potential and increasing rainfall trends. Southern Punjab and Sindh emerge as high-priority areas mainly because they show increasing rainfall trends and higher rainfall variability, which raises runoff and water-related risk. Furthermore, net command area investigation across high-priority districts suggests that out of a gross 23.7 million acres, 13.9 million acres (~ 60%) remain viable after excluding risks related to flooding, salinity, and waterlogging. The study underscores the pressing need for decentralized water storage strategies, particularly in high-risk areas, to develop climate-resilient water systems.