A global modeling approach to the hydraulic performance evaluation of a sewer network

Abstract

This paper presents an objective methodology for evaluating hydraulic sewer networks performance. Two methods of computing hydraulic performance index are presented. One method uses the nonlinear reservoir model to generate runoff hydrograph at outlets of each of the drainage basins at street section scale level. Dynamic wave equations are used for routing these hydrographs through the drainage network to obtain flow depth and level within pipes and manholes. The second method computes this index using a generalized rational hydrograph model applied to the entire upstream basin, aggregated as a single node. The hydraulic model uses a simple energy balance equation applied to each evaluated individual sewer. The case study compares these approaches by applying the methodology to small hypothetical and real networks. Slightly better results were obtained with the generalized rational method than with the nonlinear reservoir method. The generalized rational method was able to forecast measured discharges at the outlet of subcatchments with a level of accuracy acceptable to sewer network management and evaluation needs.