Calculating Rainwater Harvesting on Roofs Using Drone Photogrammetry

Abstract

This study addressed the growing scarcity of water in urban areas and proposed rooftop rainwater harvesting as a sustainable alternative. The main objective was to develop and implement a system for estimating the rainwater harvesting potential of rooftops using a drone and meteorological data. Orthomosaics were generated to calculate the area of each roof, and a weighted runoff coefficient was determined based on the predominant materials. Using a mathematical model, we estimated that the annual catchment volume ranges from 90 m³ to 285 m³, depending on the size and composition of the surface. The results showed that rooftops with a higher proportion of waterproofed concrete exhibited the greatest collection potential. Overall, the combination of drones, open source GIS, and freely available climate data provides an accurate, efficient, and replicable methodology for urban contexts with limited resources, and its adoption could reduce average residential water consumption by up to 20%.