Rainwater Harvesting Ponds Suitability maps coupling Hydrological and Socio-Economic criteria, a case study in the Shouf area, Lebanon

RainWater Harvesting Ponds (RWHPs) represent a critical adaptation measure for enhancing water availability for irrigation, reducing downstream surface runoff, and controlling soil erosion in Mediterranean mountain regions experiencing increasing hydro-climatic stress. The Shouf Biosphere Reserve (SBR) area in Lebanon presents an important case study for RWHP implementation, given the presence of hundreds of such infrastructures, built as both private and public initiative from the ‘60s and the climate vulnerability despite the high density of RWHPs in the SBR region, their historical placement was largely experience-based, or politically driven, lacking integrated hydrological, erosion, socio-economic assessment, resulting in widespread siltation and structural failure. Addressing this gap an integrated an evidence-based methodology is proposed that integrates hydrological and socio-economical factors to identify suitable RWHP sites in the area surrounding the SBR and offering a transferable methodology for comparable Mediterranean mountain contexts The study employed a multi-criteria approach integrating Geographic Information Systems (GIS), Multi-Criteria Decision-Making (MCDM), soil erosion modeling through the Revised Universal Soil Loss Equation (RUSLE), and participatory research. The results were obtained and the model calibrated through sensitivity analysis using 400 existing RWHPs mapped in the study area, which were categorized by public and private ownership. Biophysical and socio-economic criteria were integrated, including land use classification, soil data, rainfall patterns, digital elevation models, administrative boundaries, road networks, and water sources. Decision-makers and farmers' consultations provided crucial socio-economic insights and spatial context. The two final suitability maps, one for private and one for public ponds had a spatial distribution with the following statistical quartiles: Q1 = 6.15, Q2 (median) = 6.60, Q3 = 6.96 for private ponds and Q1 = 6.00, Q2 (median) = 6.50, Q3 = 7.00 for public ponds. Field-based site assessments conducted in five high-suitability areas ( >7.5) validated the model outputs, as several sites for RWHP were identified on field, demonstrating good performance of the methodology. The consultations revealed spatial variability in water sources and irrigation practices, confirming the relevance of pond infrastructure under increasing climate variability. However, the study identified the critical need for a cadastral map, currently unavailable in Lebanon, to enable a more realistic implementation process. This study represents the first applied research on RWHP suitability in the SBR area and the first to couple hydrological and socio-economical factors in the Lebanese context. The demonstrated methodology provides a valuable data-based decision support tool that can be scaled up at the national level for RWHP implementation, contributing to climate adaptation strategies in water-stressed Mediterranean regions.