Assessing Rainwater Harvesting Potential in Seawater-Based Communities Using the Case Study of Poblacion Sitangkai, Philippines

A lack of fresh water is a serious issue in communities near or surrounded by seawater, such as Sitangkai Poblacion, where they rely heavily on the ocean for their water source. QGIS with vector grid as the tool will help to study the possibility of efficient rainwater harvesting. Data processing for analysis of rainfall data from Weatherlink station in Bongao, Tawi-Tawi, and roof area digitization conducted for Sitangkai Poblacion. The spatial distribution of rainwater harvesting was assessed systematically at the 200 m x 200 m vector grid level. Data was collected on monthly precipitation during June 2023 and March 2024 to estimate possible water collection volumes. The results present significant grid-to-grid variability in the potential for rainwater harvesting, driven by roof area and regional rainfall patterns. The months when there was a lot of rainfall during the rainy season are significantly associated with the month peak rainwater harvesting occurred; this means an ideal time to boost water collection. The study demonstrates the necessity of specific rainwater harvesting approaches that focus on dominant household variables in conjunction with improved storage and holistic water handling procedures for sustainable solutions for these areas. Vector grid in QGIS can be a potential methodology for researchers to spatially analyze and guide sustainable water resource planning addressing freshwater scarcity.