Climate change is widely considered to be one of the biggest challenges to global sustainability. According to the Intergovernmental Panel on Climate Change, extreme events are likely to increase in frequency. Weather-related extreme events are the most immediate way that people experience climate change and urban areas are particularly vulnerable to such events, given their location, concentration of people, and increasingly complex and interdependent infrastructures. The current infrastructure of urban areas is aging and proving inadequate for protecting city populations. Infrastructure must be resilient, provide ecosystem services, improve social well-being, and exploit new technologies in ways that benefit all segments of urban populations and are appropriate to the particular urban context. (Source: UREx SRN)

Project 1: Urban Climate Adaptation and Vulnerability: Assessing social, ecological and technological strategies in New York City and Phoenix

Governance planning documents are one source of insight into how cities are framing urban resilience, yet there are few mechanisms to effectively and efficiently highlight the suite of social, ecological, and technological (SET) climate action strategies cities are considering. This study asks, how do cities define and prioritize climate resilience strategies within a single plan and among governance planning documents and how do strategies address current and future climate vulnerabilities? Through a content analysis of municipal planning documents from Phoenix, AZ, and New York City, NY this study examines the diverse SET strategies proposed to address climate challenges, specifically related to heat, drought, and flooding events. The findings suggest that current planning strategies tend to prioritize technological solutions and do not adequately consider system relationships. Identifying patterns in proposed and implemented plans are important steps in bridging the gap between ideas and viable adaptation actions. Results suggest ways in which governance-based strategies and vulnerability assessments form a basis for scenario visioning processes, and that can be adapted through those processes. 

Project 2. Combined sewer drainage network analysis for assessing infrastructure vulnerability to flooding in Mexico City

The purpose of this study is to identify critical census blocks (AGEB) in Mexico City that are vulnerable to nodal flooding caused by combined sewer drainage failure due to heavy precipitation in Mexico City (CDMX). The common approach for pluvial flooding (i.e., caused by extreme rainfall) assessment is a hydrological analysis estimating the flood volume. While the benefits of hydrological assessment using topographical information such as digital elevation models (DEM), land cover, rainfall-runoff data, and etc. exist, there is a limitation of conventional hydrological approaches in representing pluvial flood vulnerability and urban watersheds of CDMX due to data availability, on-going land subsidence, and interference with the built infrastructure. For these reasons, this study attempts to adopt a network topology analysis focused on infrastructure characteristics of CDMX sewer drainage system to evaluate the capacity and criticality of sewer system in a data-scarce context and the impact of sewer network topology to localized nuisance flooding.

A network topology analysis adopting graph theory is performed to assess the vulnerability of sewer drainage to nodal congestion and consequential system failure. A combined sewer system in CDMX is a network of interconnected pipes and other appurtenances to convey wastewater and stormwater by a combination of hydraulic pressure driven by mechanical pumps and gravity force driven by elevation. CDMX combined sewer system is comprised with the primary sewer drainage (receiving stormwater runoff and wastewater at drain inlets throughout the city) and the deep sewer canals (collecting sewerage from the primary drainage and transporting it to wastewater treatment plants outside of the city). This study employs a mathematical graph to represent the primary sewer drainage which is a collection of nodes representing elements at specific locations (such as pipe junctions) and links representing the pipes that define the relationship between such nodes. The study of complex networks by using techniques from graph theory can explain the vulnerability of the system to failures by analyzing the network topology.