Research

Safe-to-fail infrastructure and decision-making for climate adaptation 

 Motivated by the need for cities to prepare and adapt to unpredictable future weather conditions, we take a pragmatic approach to increasing the adaptive capacity of cities to climate change with a novel decision-making theory of safe-to-fail infrastructure. The goal of advancing safe-to-fail theory is to help guide development decisions that consider infrastructure failure and their consequences. Thus, there is an emerging need for decision makers, including policy makers, planners, engineers, and operators to understand infrastructure failures, bring this knowledge into the development process, and help adapt cities to unpredictable and changing climate risks. This approach connects to sustainability, where the cities deliberately think of and include the future cost of social, environmental and economic attributes in planning and decision-making. Safe-to-fail theory further reveals an emerging “infrastructure trolley problem” where the adaptive capacity of some urban regions is improved at the expense of others. we suggest a new decision-making perspective for resilient urban development, “safe-to-fail”, that helps manage climate adaptation trade-offs and improve city resilience.

Project 1: Fail-safe and safe-to-fail adaptation for roadway flooding in Phoenix

As climate change affects precipitation patterns, urban infrastructure may become more vulnerable to flooding. Flooding mitigation strategies must be developed such that the failure of infrastructure does not compromise people, activities, or other infrastructures. “Safe-to-fail” is an emerging paradigm that broadly describes adaptation scenarios that allow infrastructure to fail but control or minimize the consequences of the failure. Traditionally, infrastructure is designed as “fail-safe” where they provide robust protection when the risks are accurately predicted within a designed safety factor. However, the risks and uncertainties faced by urban infrastructures are becoming so great due to climate change that the “fail-safe” paradigm should be questioned. We propose a framework to assess potential flooding solutions based on multiple infrastructure characteristics using a multi-criteria decision analysis (MCDA) analytic hierarchy process algorithm to prioritize “safe-to-fail” and “fail-safe” strategies depending on stakeholder preferences. Using urban flooding in Phoenix, Arizona as a case study, We first estimate flooding intensity and evaluate roadway vulnerability using the Storm Water Management Model for a series of thunderstorms that occurred on September 8, 2014. Results show the roadway types and locations that are vulnerable. Next, We identify a suite of adaptation strategies and characteristics of these strategies, and attempt to more explicitly categorize flooding solutions as “safe-to-fail” and “fail-safe” with these characteristics. Lastly, We use MCDA to show how adaptation strategy rankings change when stakeholders have different preferences for particular adaptation characteristics.

Project 2: Expert elicitation on resilience perspectives and safe-to-fail infrastructure development 

Our current understanding of safe-to-fail is based on academic literatures. We expect that practitioner’s perspective on safe-to-fail can be dissimilar to researchers. Safe-to-fail systems thinking requires practitioners to reflect the resilience concept and system characteristics in this static decision making process with space- and context- specific subjectivity. This subjectivity of practitioners produce diverse perspectives on resilience and safe-to-fail from decision maker’s side and help researchers to understand how practitioners conjugate the theoretical concept of resilience in climate adaptation practices. This study explores practitioners’ perspectives on implementing resilience in decision practices for developing safe-to-fail infrastructure, which are recognized as reflecting the cultural, social, institutional, spatial and historical contexts in which their perspective is constructed. We utilize Q method – a research method used to study an individual’s subjectivity – to assess how practitioners view resilience as important theory for planning infrastructure and how they arrive at these conclusions. Q method allows us to explore diverse perspectives on employing resilience concepts and strategies and to recognize a shared vision among practitioners to achieve a safe-to-fail system in a city. 

Urban Resilience to Extremes Weather Events

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.

Nature-based solutions for Urban Resilience in the Anthropocene (NATURA)

The Nature-based Solutions for Urban Resilience in the Anthropocene (NATURA) project links networks in Africa, Asia-Pacific, Europe, North and Latin America, and globally to enhance connectivity among the world's scholars and practitioners and improve the prospects for global urban sustainability. NATURA exchanges knowledge, shares data, and enhances communication among research disciplines and across the research-practice divide to advance urban resilience in face of growing threats of extreme weather events.

As an important part of knowledge sharing, researchers and practitioners will work together on applications of nature-based solutions (NBS) in a wide range of social, ecological, and technological contexts addressing five gaps:

For more information, please visit www.natura-net.org.

Nature-based solutions for Urban Flood Mitigation

Around the world, natural catchments are being continuously altered by humans for residential, industrial and commercial purposes. These activities directly affects the natural environment and often lead to irreversible changes. Urbanization results in the increased runoff, decreased infiltration and groundwater recharge, increased water temperatures in urban waterways, and altered habitat behaviours, all leading to reduced surface water quality. Though stormwater management systems are commonly implemented to contend with surface runoff from impervious areas, alternative techniques such as green roofs, bio-retention systems, permeable pavements, vegetative swales, and constructed wetlands and ponds are becoming popular as nature-based solutions (NBS) to mitigate risks of urban flooding and, in some cases, to complement existing stormwater management systems. Ideally, these alternative measures need to be distributed throughout the urban catchments in order to support natural hydrologic and environmental functions, associated with the retention, detention, evaporation, and recycling of stormwater.

More project details will be updated shortly.