Influence Of Engineered Soil Media Composition To The Hydraulic Performance In Rain Garden System

Stormwater had been identified as one of the factor that causes surface runoff on the ground. The runoff is caused by the inability of the water to infiltrate into the soil, causing the water to stay on the ground and causes major problems such as flooding and water ponds. Rain garden is one of the best management practice approach in handling this matter. A rain garden promotes infiltration to the soil beneath, reducing the surface runoff thus solving floods problems. The objective of this study is to investigate the effects of soil media composition to the hydraulic performance in a rain garden system. Three types of soil media composition is used, which are fine river sand, coarse river sand, and leaf composts, which are made up of shredded dry leaves. The study is done by using sand column to represent a bioretention system, which are divided into three layers; the drainage layer, soil filter layer and ponding layer at the top. In order to analyse the hydraulic performance of the system, a few parameters had been identified as indicators in this study, which are the flow of water, soil hydraulic conductivity, water removal efficiency, and water holding capacity. A coarser grain material had been known to give a greater flow and hydraulic conductivity, however, an addition of fine sand and leaf composts helps in water removal and water drainage, which is also a good parameter for a better rain garden system.
Keywords: rain garden, best management practice, hydraulic conductivity, soil media composition, water removal efficiency