Sustainable flood management in nonurban-urban watersheds using green-grey infrastructures: A cooperative perspective

Flood management in complex watersheds that include both urban and natural areas presents significant challenges due to the contrasting hydrological and hydraulic dynamics of these regions. This study proposes an integrated framework that combines Green Infrastructure (GI) in urban areas with detention dams in upstream nonurban regions to mitigate flood risks comprehensively. Using the Wadi Al-Sarami watershed in Oman as a case study, the research employs multi-objective optimization algorithms to design and evaluate potential scenarios for both interventions. Detention dams were optimized to reduce peak flow entering urban areas, while GI measures were configured to enhance infiltration and manage local runoff. The scenarios were then integrated to develop macro-level flood management plans that implement a balanced approach across the watershed. A cooperative game theory framework was applied to resolve conflicts among key stakeholders, namely the Ministry of Agriculture, Fisheries, and Water Resources (MAFWR), Sohar Municipality (SM), and urban residents. This study also applied Shapley and Tau value methods for allocation to ensure a fair distribution of benefits among the stakeholders and to encourage cooperation. The results indicated that the integrated approach could achieve a peak flow reduction of up to 72.5% and a 71.8% decrease in urban runoff volume. This paper presents a framework that shows that technical optimization needs to be integrated with stakeholder collaboration for sustainable flood management. This research provides a scalable and adaptable solution for addressing the increasing flood risks associated with urbanization in complex watersheds.