One of the most critical processes for the long-term management of groundwater resources is Groundwater Potential Zonation (GWPZ). Despite their importance, traditional groundwater studies are costly, difficult, complex, and time-consuming. This study aims to investigate GWPZ mapping for the Al-Qalamoun region, in the Western part of Syria. We combined the Multi-Influence Factor (MIF) and Analytic Hierarchy Process (AHP) methods with the Geographic Information Systems (GIS) to estimate the GWPZ. The weight and score factors of eight factors were used to develop the GWPZ including drainage density, lithology, slope, lineament density, geomorphology, land use/land cover, rainfall, and soil. According to the findings, about 46% and 50.6% of the total area of the Al-Qalamoun region was classified as suitable for groundwater recharge by the AHP and MIF methods, respectively. However, 54% and 49.4% of the area was classified as having poor suitability for groundwater recharge by the AHP and MIF methods, respectively. These areas with poor suitability can be utilized for gathering surface water. The validation of the results showed that the AHP and MIF methods have similar accuracy for the GWPZ; however, the accuracy and results depend on influencing factors and their weights assigned by experts.

Today's world is plagued with water shortages, especially in developing countries. The problem is made worse by increasing water demands and decreasing rainfall occurrences in arid and semi-arid areas. Rainwater harvesting (RWH) has the potential to be a viable solution for this issue, as it can augment existing water supplies in the long term. This study aimed to identify suitable areas for RWH using a multi-criteria decision analysis (MCDA) based on the analytic hierarchy process (AHP) method, combined with geographic information system (GIS) and remote sensing (RS) techniques. This study has been carried out in the Al-Qalamoun Basin, the western part of Syria, which has not been studied for rainwater harvesting before. To fill this gap, a potential RWH map was created in the Al-Qalamoun Basin using nine factors, which are land use and land cover (LULC), soil texture, slope, rainfall, curve number (CN), stream order, distance to faults, distance to roads, and distance to residential areas. All thematic layers were allocated appropriate weights and combined using the weighted Overlay process (WOP) in ArcGIS 10.8 to produce a RWH map of the study area. The findings indicated that about 18.1% of the total study area was classified as most suitable and suitable for RWH. Validation of the RWH map with the existing dams indicated that the methodology adopted in this study had a high capacity to identify sites suitable for RWH. The study presents a useful and inexpensive tool for decision-makers to avoid unsuitable sites and focus on the most suitable sites for constructing dams.