Developing a Simple Approach for Estimating the Infiltration Capacity of Infiltration Gutters

Abstract

Infiltration gutters are often applied to address the urban hydraulic impact resulting from rapid urbanization. Despite their applicability in many of Asia's fast growing middle-sized cities, their characteristics and performance, however, have not been properly understood for supporting sound design. To this end, this study assessed their performance and proposed a simple approach based on Darcy's law for estimating the infiltration capacity of an infiltration gutter. Permeable-brick infiltration gutters were constructed and tested on-site. Water infiltrated through three scenarios, i.e., the surfaces of two vertical sides (NFS-2S), the bottom (NFS-B), and three faces (NFS-3S) of the gutter, which were measured under steady state conditions. Test results indicate that specific infiltration area per unit length (Au.s), denoting the final infiltration rate divided by the saturated hydraulic conductivity of the soil, and the designed water depth (H) are linearly dependent on each other for NFS-2S and NFS-3S but not for NFS-B. Experimental results also indicate that when the bottom of the gutter is clogged, the gutter still retains about 93% of its infiltration capacity. Based on these on-site tests, this study thereby developed a simple tool using Darcy's law to design infiltration gutters.