Abstract
Rainwater collection and effective water resource management are essential for boosting water availability, land productivity, and groundwater levels in dry places like Iraq, which is susceptible to climate change and drought. This work develops a GIS-based rainfall harvesting (RWH) method in the western Karbala Governorate, Iraq, to address water shortages and future groundwater replenishment and irrigation demands. LARS-WG 8 was used to study how climate change affects rainfall in Karbala to assess whether rainwater collection is feasible and sustainable. The research found that annual rainfall in the Karbala governorate would grow by 18%-24 % in the 21st century, highlighting the necessity of rainwater collection for water resource sustainability. Themed RWH layers were created using ArcGIS software and the multi-criteria decision-making technique. The Analytic Hierarchy Process determined tier weights based on seven factors. Based on literature, local experts, and statistics, rainfall, curve number, slope, stream order, soil texture, land use, and runoff depth were considered. The consistency ratio of 2.6 % validated the comparison component weights and showed that each criterion was appropriately weighted. The most RWH weights (47 % total) were rainfall and runoff depth. The map classified RWH areas as high, medium, or low appropriateness. Results indicated the three groups were uniformly distributed. The results appeared; study area lands have 34.4 % (745 km(2)) medium suitability, 34.2 % (752 km(2)) low suitability, and 31.8 % (697 km(2)) high suitability, largely in the central sections. Sensitivity analysis was applied to find the most sensitive characteristics, establish how each of the seven criteria affects the ideal RWH locations, and ensure that future research focuses on the right elements. The results of this study are novel in Karbala and help policymakers develop effective water management and resource allocation policies, promoting RWH as an alternative water supply in West Karbala and other water-scarce locations.