Quantifying the Resilience of Urban Drainage Systems Using a Hydraulic Performance Assessment Approach

Abstract

Although considerable progress has been made towards achieving sustainable urban water management, urban drainage systems (UDSs) are increasingly threatened by multiple and uncertain drivers of future change. Building the resilience of UDSs to flooding is increasingly recognised as an imperative to promoting the long term sustainability of the urban areas they serve. This paper describes a methodology that combines the use of hydraulic performance assessment with utility performance functions to quantify the resilience of UDSs during flooding (exceedance) conditions. Utility performance functions, which relate the overall UDS performance to flood depths, are derived from existing flood depth-damage data for UK residential properties for various rainfall return periods and are used to estimate UDS residual functionality and hence resilience to pluvial flooding. The study shows that by introducing a storage tank for flow attenuation, the duration of nodal flooding and the flooded volume can be reduced by 6 to 10% and 18 to 38%, respectively and the overall system resilience to flooding can be increased by 8.0 to 9.5%.