Ensuring Water Justice and Achieving Sustainable Development Goals in Megacities Through Cooperative Bargaining Solutions

Abstract Water scarcity and insecurity remains a critical challenge for the megacities of Global South, disproportionately impacting vulnerable and low-income communities. In Karachi, one of Pakistan’s largest cities, almost 45 percent of domestic water demands are unmet due to governance failures and infrastructural inefficiencies. Our study applies a novel integrated Water Evaluation and Planning (WEAP)-Nash Bargaining Solution (NBS) framework that simulates future water demands and optimizes fair and equitable allocation of water among the seven administrative divisions of the city. Under WEAP, the projected satisfaction ratio with no intervention declined from 60 percent in 2023 to 30 percent in 2040, whereas the integrated strategy improved the demand satisfaction to 100 percent for all seven districts by 2036. Our results also indicate that water allocation under NBS, weighted by the Multidimensional Poverty Index (MPI), would enhance equity at the district level with Karachi East’s allocation increasing from 60 to 96 percent in addition to the allocation improvements for other marginalized areas. These results highlight the importance of embedding socio-economic considerations within technical water allocation models. This would also directly contribute to achieving Sustainable Development Goals (SDGs) 6 and 10, ensuring access to water and reducing inequality, respectively.