Multi-decade analysis of flood risks to community infrastructure in Philadelphia

Abstract

Flood events increasingly pose a significant threat to community infrastructure (hereafter CI), which can potentially disrupt their essential functions and services within communities. This is particularly concerning in coastal urban areas, where the complexity of urban flood dynamics is exacerbated by their exposure to coastal, fluvial, and pluvial flooding. To address such challenge, we characterize flood risks to CIs in Philadelphia based on property-level simulations of flood events over a 35-year period (1985–2019) using an integrated coastal-hydrologic-hydrodynamic modeling approach. The characterizations of CI flood risks consider multiple perspectives, including the relative distributions of flood exposures, hazards, risks to various CI types by different flood drivers, assessments of individual and aggregated flood damages, and geospatial patterns of CI flood risks in relation to flood-related variables. Additionally, a scenario analysis examines indirect and cascading disruptions of interconnected infrastructure caused by flood-induced power outages at substations. Our analysis identifies frequent, localized damages associated with fluvial flood events as well as severe, extensive damages from compound coastal-fluvial-pluvial flood events. Notably, commercial and industrial CI facilities are particularly susceptible to floods due to their concentrations across low-lying areas. Furthermore, our study presents an approach that, for the first time, utilizes concentration curves for infrastructure, to enhance flood management planning by prioritizing flood mitigation measures tailored to identified flood risk characteristics. Overall, the CI risk characterizations for past flood events provide a foundational understanding that can inform targeted allocations of limited resources towards risk-based investments in flood management and establish a baseline for future risk assessments.