Transforming flood risks into water resources - A multivariate GIS suitability analysis of stormwater harvesting in Palestine

The Palestinian West Bank has an arid to semi-arid climate, characterized by chronic water scarcity and recurring flash floods. To reduce flood susceptibility and increase water security, this study employs a geographic information system (GIS)-based multi-criteria decision analysis to identify suitable sites for stormwater harvesting in a politically and environmentally sensitive region. This approach includes stormwater harvesting system identification, equal and Analytical Hierarchy Process (AHP)-based variable weighting, suitability mapping, sensitivity analysis, and result triangulation. Hydrological and administrative overlays were used to refine the analysis and assess feasibility. Results indicate that while flood events are underreported, over 5% of the study area is at high risk of recurring floods. Constructed wetlands, retention ponds, and detention ponds emerged as the most suitable systems, while other methods demonstrated more localized applicability. The AHP technique identified precipitation and population density as the two prioritized criteria in their respective classes for suitability analysis. Sensitivity analysis validated the robustness of both equal- and expert-weighted models, with nuanced advantages for expert-weighted maps. Accounting for seasonal variability and inefficiencies, the estimated annual harvestable volume of 305 MCM could cover domestic water use while reducing hazards in highly suitable, high-risk zones. However, because most suitable sites lie within Israeli-administered territory, implementation relies on transboundary collaboration. These findings demonstrate that stormwater harvesting remains a critical climate adaptation strategy in regions contending with both environmental vulnerabilities and geopolitical constraints.