Distributed modelling of urban runoff using a meta-channel concept

Abstract

Hydraulic flood routing is advantageous for computational accuracy; however, it requires individual calculations of an extensive pipe network in the case of a two-dimensional analysis. In this study, a method for considering the characteristics of a two-dimensional pipe network has been developed using the meta-channel concept to simplify the detailed calculations involved in the estimation of runoff from urban catchments. In essence, the meta-channel concept turns a two-dimensional pipe network into a one-dimensional pipe with an effective hydraulic geometry. Once such geometry has been identified, the flood routing can then be performed for an urban drainage system. A nonlinear diffusion wave equation, derived from the Saint-Venant equation, was used for flood routing, with an explicit method used for the numerical solution. The celerity and diffusion coefficients, which are two parameters of the diffusion wave equation, were estimated for the Goonja drainage from a two-dimensional pipe network using the meta-channel concept. A comparison of the results of the meta-channel-based pipe routing with the distributed SWMM simulation and observed data, showed close similarities, and identified the applicability of the meta-channel concept in an urban drainage setting.