JAUE2022-025: Efficacy of Rain Barrels and Rain Gardens to Reduce Urban Pluvial Flooding

Abstract

In recent years, flooding in densely built-up residential areas has tended to increase because of the increased frequency of heavy rain and climate change. Urban pluvial flooding mitigation is needed by reducing the runoff of sewer systems with green infrastructure solutions. Rain barrels (RBs) and rain gardens (RGs) are considered effective stormwater management methods. This study aimed to verify the effectiveness of RBs and RGs in reducing urban pluvial flooding in densely built-up residential areas. This research takes a case study in Miyahara-Cho, Saitama City. This research involves the analysis of the depth of the outlet, the total runoff of the sewer systems, and the flood condition in the sewer to verify the rainwater runoff control effect of RBs and RGs through simulation using EPA stormwater management model version 5.1 (SWMM-5.1). This study simulates two main types of rainfall events: short duration and long duration. The result of short-duration rainfall showed that the combination of rain barrels and rain gardens is highly effective and can be expected to reduce the impact of excess runoff. In the case of long-duration rainfall, the volume and speed of stormwater runoff of the first peak rainfall are reduced.