RAINWATER HARVESTING FOR FLOOD PEAK REDUCTION IN WAY AWI CATCHMENT, INDONESIA

Abstract

This study is motivated by floodings which occur frequently in Jagabaya village, Way Awi catchment, Bandar Lampung city, Indonesia. In addition to the intensity of rainfall, this area is considered as an urban area with intense housing and insufficient drainage capacity during heavy rain. This study aims to analyze flood peak reduction by simulating the application of rain barrels for each house. The volume of rain barrels used in the simulation is 0.5 to 5 m3. An Intensity-Duration-Frequency (IDF) curve is generated using
short-duration rainfall data (i.e. 5, 10, 15, 30, 60, 120, 180, 360 and 720 minutes) recorded from Panjang Meteorological Bureau, Lampung. The rational method, a simple rainfall-runoff model, is used to calculate runoff generated both from catchment and rooftop. The result shows that the application of rain barrels may reduce flood peak up to 28% for 2 year return period of flood, while for 100 year return period of flood, the reduction may reach 13.64%. From this study, it can be concluded that rainwater harvesting utilizing rain barrel is significant in reducing flood peak. Furthermore, this result can be used to persuade both the society as well
as the local government to do such flood mitigation in this densely populated urban area.