A GIS-based approach to determine the priority area for rainwater harvest in Kupang

Kupang, a pivotal economic and administrative hub in Nusa Tenggara Timur, Indonesia, faces recurring droughts resulting in crop failures, food insecurity, and health problems. Addressing this water crisis entails rainwater harvesting as a potential solution. This study establishes a comprehensive framework for prioritizing rainwater harvesting areas in Kupang. Using the weighted overlay method and open-source GIS software, our approach involves three stages: identifying drought and flood priority zones, defining suitability indicators, and quantifying the potential of rainwater harvesting systems. By leveraging climatological, geological, and hydrological information, we determine priority areas for drought and flood management. Our analysis of rainwater harvesting suitability integrates climatological information, land use and land cover mapping, runoff potential assessment, and water use index. Quantification of rainwater harvesting system requirements hinges on rooftop area and population data. The entire wards in Kupang are classified as high priorities for drought mitigation. Therefore, rainwater harvesting is a viable strategy for all wards. The most prioritized and in-demand wards, Oesapa, Sikumana, Lasiana, and Liliba, have the potential to install a minimum of 12,000 rainwater harvesting systems, each with a 1500-liter volume barrel.