Modelling of Grassed Road Divider as Bio-Retention System for Urban Road Drainage

Abstract

An evaluation on the applicability of bio-retention system in grassed road divider under high rainfall of equatorial region was conducted by developing computer-aided stormwater models using USEPA SWMM 5.1. The models simulated road runoffs with and without bio-retention systems. A single unit of bio-retention system tested here was 3 m in width, 6 m in length with 150 mm of ponding depth and 600 mm of soil/storage depth. Results indicated that soil types of loamy sand, sandy loam and loam showed similar performance in reducing runoff. With installation of bio-retention system, road runoff could be reduced 40-50% when subjected to 60 minutes of 2-, 5- and 10-year ARI rain events. The results obtained from the simulation were encouraging that bio-retention system in grassed road divider could function to augment the existing urban road drainage.