Graph-theoretical representation of impact propagation in urban stormwater networks

Abstract

Any disruptions in urban stormwater networks (USNs), such as sewer or manhole failures, can propagate impacts beyond their immediate spatial location (e.g., upstream or downstream). However, determining where and to what extent these impacts propagate is often challenging due to the complex hydraulic behaviour of such systems. This study introduces a modelling framework using graph theory to represent the consequences of failure propagation. The framework quantifies the impacts of junction failures on other elements of USNs through hydrodynamic modelling. These impacts are then decoupled from the physical USN topology and represented as a directed and weighted graph, termed "impact network", where edge weights capture the actual consequences beyond the failure’s point of origin. The application of the proposed framework was demonstrated through systematic investigations of a real-world case study. This analysis led to the identification of the most influential nodes driving impact propagation and the most affected nodes exposed to the propagated impacts. Furthermore, the spatial interconnections between the impact network and critical urban locations were analysed, enabling the prioritisation of nodes of strategic importance.