Rainfall-Runoff Simulation of Lab-Scale Roof Catchment for Rainwater Harvesting Design

One of the most pervasive anthropogenic activities is urbanization, which transforms natural lands into impervious surfaces that cannot be permeated by rainwater. Since the majority of rainwater remains above the surface, surface runoff is increased. Water abstraction in the Philippines increases annually. Rainwater harvesting (RWH) systems have been used as an alternative water source to meet demand. The main objective of this study is to characterize roof runoff harvested from urban areas in the Philippines. The results from this study aim to provide design criteria for building a RWH system. A rainfall simulator is constructed in order to simulate various rainfall events. Regression analysis was used to calculate the runoff coefficient to provide a concept of the potential design. Findings show that starting at 20.8 mm/hr at 0.5 runoff coefficient, the rainfall intensity drops by 16.4 mm/hr as the runoff coefficient increases. Linear rainfall-runoff relationship aids design, more research is needed for variations