Moving from reliability to resilience-based evaluation of urban drainage infrastructure: A case study of Kampala, Uganda

Abstract

The performance of existing urban drainage systems (UDSs) in various cities is increasingly threatened by multiple and uncertain threats such as climate change, rapid urbanisation and infrastructure failure which lead to negative flooding impacts and consequences. However, conventional urban drainage design and rehabilitation approaches tend to focus on minimising the probability of hydraulic failures resulting from a chosen design storm as a basis for determining the flood protection service level delivered by a given system (Butler and Davies, 2011; Sun et al., 2011; Thorndahl and Willems, 2008). Such hydraulic-reliability based approaches may be insufficient for ensuring accepteable flood protection levels in cities during unprecedented extreme events. Consequently, to enhance the resilience of UDSs, new and computationally efficient evaluation approaches that can enable explicit consideration of vital interactions between threats, system performance and resulting failure impacts during both normal and exceptional loading conditions are required (Butler et al., 2014; Kellagher et al., 2009; Mugume et al., 2015).