Integrating sustainable urban drainage system into storm water management for an efficient municipal drainage :

Abstract

Flooding of urban areas is a worldwide problem as cities grow and the amounts of impermeable surfaces increase generating more surface runoff. This poses significant challenges to traditional storm water management systems, leading to increased flooding. This thesis explores the integration of Sustainable Urban Drainage Systems (SUDS) as a solution for a more resilient municipal drainage network for Kasese Municipality. The research evaluated the performance of the existing natural and artificial drainage systems within the municipality using hydrologic and hydraulic models in PCSWMM. Rainfall frequency analysis was carried out using the Gumbel distribution after best fit tests and the design storms that correspond to the 2, 5, 10, 25, 50, 100, 200 and 500-year return periods were computed. Using a high-resolution Digital Elevation Model (DEM) of 12.5m, watershed delineation was carried out and the sub-basin parameters calculated accordingly. Using the watershed parameters obtained the design storm and the hydraulic properties of the existing drainage network collected from the field as inputs to PCSWMM, runoff simulations were carried out. The analysis revealed that the current system experiences frequent flooding and high flow rates, highlighting the need for improvement. To address this issue, a multi-objective approach was adopted. Firstly, the TOPSIS method was employed to identify the most suitable SUDS option for stormwater runoff control. In light of the analysis, infiltration trenches emerged as the most effective solution. Subsequently, an infiltration trench design was developed and incorporated into the PCSWMM model using LID controls tool. The results demonstrated a significant reduction in flooding and flow rates following the inclusion of the infiltration trench. This finding suggests that integrating SUDS, particularly infiltration trenches, offers a promising approach to enhance the resilience and sustainability of municipal drainage systems for managing urban stormwater runoff. Keywords: Sustainable Urban Drainage Systems (SUDS), Stormwater Management, Hydraulic Model, Hydrologic Model, PCSWMM, TOPSIS, Urban flooding.