A Geographic Analysis of the Resilience of Urban Infrastructure Networks to Extreme Events

The main objective of this study is to simulate the impacts of extreme events on urban infrastructure and propose a new vulnerability assessment method to quantify these impacts on urban infrastructure networks. In this research we use deterministic and probabilistic approaches to simulate different extreme events (i.e., extreme flooding and earthquake with deterministic approaches and extreme flash floods with a probabilistic approach) on transportation networks, i.e., road systems, varying in intensity and type, and their impacts will be measured in a novel Vulnerability Surface (VS) technique. The central hypotheses of this research are twofold. First, extreme events can be simulated spatially using Geographic Information Systems (GIS) methods and also by means of climate models. This hypothesis naturally depends on the type of extreme event. The second hypothesis of this research assumes that the resilience of urban infrastructures can be partially captured from a complex network perspective. The emerging field of network science now fairly has established and it has proven to be particularly useful to study matters of resilience. Broadly, resilience in spatial systems like road networks is dependent on many factors, including system size (i.e., number of nodes and links) and topological structure of the network. Expectedly, resilience also depends on geography, and cities that are naturally more at risk will tend to be less robust, and therefore the notion of resilience rapidly becomes sensitive to individual contexts. Here, the main objective is not to predict exactly when and where extreme events happen, but to simulate a vast array of scenarios so that cities can develop protocols to follow if or when these events happen. Moreover this research is significant because extreme events are by nature unpredictable in the longer term and their impacts may increase due to changes in climate conditions. The overall research goal of is to harvest the complexity of urban infrastructure to better understand infrastructure resilience and offer design recommendations for more resilient infrastructure designs. Thanks to the simplicity of the method and the free accessibility of the data, the proposed framework of this research can be reproduced in any city around the world and researchers can use the results as guidelines to design future infrastructure projects. Moreover, comparison analysis of different cities for different climate scenarios can help local and national authorities to prioritize their adaptation policies (e.g., infrastructure maintenance) in regions with higher risk of vulnerability and assign more budgets for these regions.