Integrating Climate Projections and Geospatial Analysis to Identify Rainwater Harvesting Suitability in Lombok Island, Indonesia

Water scarcity is a growing challenge exacerbated by climate change, particularly in regions like Lombok Island, Indonesia, where water resources are crucial for sustainable development. This research aims to identify suitable locations for Rainwater Harvesting (RWH) by integrating geospatial analysis, the Analytic Hierarchy Process (AHP), and climate projections using CMIP6 data. The study utilizes multiple parameters, including rainfall, land use/land cover (LULC), slope, drainage density, soil texture, and runoff depth, to develop a comprehensive suitability map for RWH.

Historical rainfall data from CHIRPS (1981–2010) and future rainfall projections for mid-century (2031–2060) and end-century (2071–2100) under SSP2-4.5 and SSP5-8.5 scenarios were analyzed to account for climatic variations. Each parameter was processed using geospatial tools, with weights assigned through AHP based on expert input, ensuring a robust multi-criteria decision-making framework. Suitability maps were generated for each temporal scenario, highlighting areas with high to very high potential for RWH, particularly in North and East Lombok.

The results reveal dynamic shifts in RWH site suitability over time, with increasing precipitation under SSP5-8.5 scenarios expanding high-suitability areas. These findings highlight the potential for RWH to manage water resources adaptively in response to projected climate variability. By aligning the outputs with existing water management infrastructure, such as dams, the study provides actionable insights for regional planners and policymakers.