Supply chain complexity is perceived to exacerbate the supply disruptions or shocks experienced by a city. Here, we calculate two network measures of supply chain complexity based on the relative number—horizontal complexity—and relative strength—vertical complexity—of a city’s suppliers. Using a large dataset of more than 1 million annual supply flows to 69 major cities in the United States for 2012–2015, we show that a trade-off pattern between horizontal and vertical complexity tends to characterize the architecture of urban supply networks. This architecture shapes the resistance of cities to supply chain shocks. We find that a city experiences less intense shocks, on average, as supplier relative diversity (horizontal complexity) increases for more technologically sophisticated products, which may serve as a mechanism for buffering cities against supply chain shocks. These results could help cities anticipate and manage their supply chain risks.
Extreme weather-related events are showing how infrastructure disruptions in hinterlands can affect cities. This paper explores the risks to city infrastructure services including transportation, electricity, communication, fuel supply, water distribution, stormwater drainage, and food supply from hinterland hazards of fire, precipitation, post-fire debris flow, smoke, and flooding. There is a large and growing body of research that describes the vulnerabilities of infrastructures to climate hazards, yet this work has not systematically acknowledged the relationships and cross-governance challenges of protecting cities from remote disruptions. An evidence base is developed through a structured literature review that identifies city infrastructure vulnerabilities to hinterland hazards. Findings highlight diverse pathways from the initial hazard to the final impact on an infrastructure, demonstrating that impacts to hinterland infrastructure assets from hazards can cascade to city infrastructure. Beyond the value of describing the impact of hinterland hazards on urban infrastructure, the identified pathways can assist in informing cross-governance mitigation strategies. It may be the case that to protect cities, local governments invest in mitigating hazards in their hinterlands and supply chains.
more » « less- Award ID(s):
- 1934933
- NSF-PAR ID:
- 10524332
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Environmental Research: Infrastructure and Sustainability
- Volume:
- 4
- Issue:
- 3
- ISSN:
- 2634-4505
- Format(s):
- Medium: X Size: Article No. 035004
- Size(s):
- Article No. 035004
- Sponsoring Org:
- National Science Foundation
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Abstract Cities are the drivers of socioeconomic innovation and are also forced to address the accelerating risk of failure in providing essential services such as water supply today and in the future. Here, we investigate the resilience of urban water supply security, which is defined in terms of the services that citizens receive. The resilience of services is determined by the availability and robustness of critical system elements or “capitals” (water resources, infrastructure, finances, management efficacy, and community adaptation). We translate quantitative information about this portfolio of capitals from seven contrasting cities on four continents into parameters of a coupled system dynamics model. Water services are disrupted by recurring stochastic shocks, and we simulate the dynamics of impact and recovery cycles. Resilience emerges under various constraints, expressed in terms of each city's capital portfolio. Systematic assessment of the parameter space produces the urban water resilience landscape, and we determine the position of each city along a continuous gradient from water insecure and nonresilient to secure and resilient systems. In several cities stochastic disturbance regimes challenge steady‐state conditions and drive system collapse. While water insecure and nonresilient cities risk being pushed into a poverty trap, cities which have developed excess capitals risk being trapped in rigidity and crossing a tipping point from high to low services and collapse. Where public services are insufficient, community adaptation improves water security and resilience to varying degrees. Our results highlight the need for resilience thinking in the governance of urban water systems under global change pressures.
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Abstract Research purpose. Smart City technologies offer great promise for a higher quality of life, including improved public services, in an era of rapid and intense global urbanization. The use of intelligent or smart information and communication technologies to produce more efficient systems of services in those urban areas, captured under the broad rubric of “smart cities,” also create new vectors of risk and vulnerability. The aim of this article is to raise consideration of an integrated cross-domain approach for risk reduction based on the risks smart cities are exposed to, on the one hand, from natural disasters and, on the other, from cyber-attacks. Design / Methodology / Approach. This contribution describes and explains the risk profile for which smart cities are exposed to both natural disasters and cyber-attacks. The vulnerability of smart city technologies to natural hazards and cyber-attacks will first be summarized briefly from each domain, outlining those respective domain characteristics. Subsequently, methods and approaches for risk reduction in the areas of natural hazards and ICT security will be examined in order to create the basis for an integrated cross-domain approach to risk reduction. Differences are also clearly identified if an adaptation of a risk reduction pattern appears unsuitable. Finally, the results are summarized into an initial, preliminary integrated cross-domain approach to risk reduction. Findings. Risk management in the two domains of ICT security and natural hazards is basically similar. Both domains use a multilayer approach in risk reduction, both have reasonably well-defined regimes and established risk management protocols. At the same time, both domains share a policymaking and policy implementation challenge of the difficulty of appropriately forecasting future risk and making corresponding resource commitments to address future risk. Despite similarities, different concepts like the CIA Triad, community resilience, absorption capacity and so on exist too. Future research of these concepts could lead to improve risk management. Originality / Value / Practical implications. Cyber-attacks on the ICT infrastructure of smart cities are a major vulnerability – but relatively little systematic evaluation exists on the topic. Likewise, ICT infrastructure is vulnerable to natural disasters too – and the risk of more severe natural disasters in the context of a global trend toward massive cities is increasing dramatically. Explicit consideration of the issues associated with cross-domain integration of reduction of interdependent risk is a necessary step in ensuring smart city technologies also serve to promote longer-term community sustainability and resilience.more » « less
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Abstract Cycles of wildfire and rainfall produce sediment‐laden floods that pose a hazard to development and may clog or overtop protective infrastructure, including debris basins and flood channels. The compound, post‐fire flood hazards associated with infrastructure overtopping and clogging are challenging to estimate due to the need to account for interactions between sequences of wildfire and storm events and their impact on flood control infrastructure over time. Here we present data sources and calibration methods to estimate infrastructure clogging and channel overtopping hazards on a catchment‐by‐catchment basis using the Post‐Fire Flood Hazard Model (PF2HazMo), a stochastic modeling approach that utilizes continuous simulation to resolve the effects of antecedent conditions and system memory. Publicly available data sources provide parameter ranges needed for stochastic modeling, and several performance measures are considered for model calibration. With application to three catchments in southern California, we show that PF2HazMo predicts the median of the simulated distribution of peak bulked flows within the 95% confidence interval of observed flows, with an order of magnitude range in bulked flow estimates depending on the performance measure used for calibration. Using infrastructure overtopping data from a post‐fire wet season, we show that PF2HazMo accurately predicts the number of flood channel exceedances. Model applications to individual watersheds reveal where infrastructure is undersized to contain present‐day and future overtopping hazards based on current design standards. Model limitations and sources of uncertainty are also discussed.
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Abstract The security, resilience, and sustainability of urban water supply systems (UWSS) are challenged by global change pressures, including climate and land use changes, rapid urbanization, and population growth. Building on prior work on UWSS security and resilience, we quantify the sustainability of UWSS based on the performance of local sustainable governance and the size of global water and ecological footprints. We develop a new framework that integrates security, resilience, and sustainability to investigate trade-offs between these three distinct and inter-related dimensions. Security refers to the level of services, resilience is the system’s ability to respond to and recover from shocks, and sustainability refers to local and global impacts, and to the long-term viability of system services. Security and resilience are both relevant at local scale (city and surroundings), while for sustainability cross-scale and -sectoral feedbacks are important. We apply the new framework to seven cities selected from diverse hydro-climatic and socio-economic settings on four continents. We find that UWSS security, resilience, and local sustainability coevolve, while global sustainability correlates negatively with security. Approaching these interdependent goals requires governance strategies that balance the three dimensions within desirable and viable operating spaces. Cities outside these boundaries risk system failure in the short-term, due to lack of security and resilience, or face long-term consequences of unsustainable governance strategies. We discuss these risks in the context of poverty and rigidity traps. Our findings have strong implications for policy-making, strategic management, and for designing systems to operate sustainably at local and global scales.
