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Inland levees can amplify flood risk in unprotected communities by altering floodwater levels away from their location. While these nonlocal effects of levees, which we term flood teleconnections, have been studied for specific river segments, their impact on flood risks along a river network remains underexplored. By combining data-driven, hydrodynamic, and economic models, we quantify the magnitude, spatial distribution, and economic damages associated with flood teleconnections for a large river network system with extensive levees. We find that due to levees, the 100-year flood inundation extent grows by 25% of the total levee-protected area regionally, and the flood inundation depth increases by up to 2 m at specific locations. Levees also increase the vulnerability of unprotected, marginalized communities to flooding. Our results demonstrate that flood teleconnections are spatially widespread, involve unaccounted costs, and can lead to flood inequities. These findings will be critical to climate adaptation efforts in flood-prone regions. 

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.

 

Through the trade of products and services, cities indirectly depend on distant water sources to function, prosper, and grow. To fully account for indirect (virtual) water dependencies, virtual water flows need to be known along complex supply chains. To this purpose, we build a new environmental multiregional input–output model for U.S. regions. The model is used to quantify the domestic, blue virtual water flows and analyze the water footprints of 69 major U.S. cities. Our results show a large inequality in the urban water consumed for economic production: just 7 out of the 69 cities included in this study account for 35% of the U.S. national water footprint of production. This is due to the production of water‐intensive agricultural products in the metropolitan areas of western cities. The inequality reduces for the urban water footprint of consumption because, through the supply chains of industrialized food sectors, western virtual water is partially transferred to eastern cities as final demand. The water embodied in industrial products and services tends to be higher in western cities than in eastern cities; that is, the water embodied in food services could be several times higher in Los Angeles than in New York City. Trade hub cities attract large inflows of products which are mostly transformed for consumption elsewhere. Thus, the omission of product interdependencies within trade hub cities can increase by several times their water footprints of consumption. Overall, the proposed model is able to enhance subnational estimates of U.S. virtual water flows.

 

As complex systems, urban stormwater networks (USNs) may reveal emergent features (e.g., scaling) and sudden changes in behavior, which can lead to unanticipated impacts. We explored this through the USN properties of connectivity, heterogeneity, and scaling, which were quantified using outputs from a hydrological model and network dispersion mechanisms. The network properties were determined retrospectively in space and time by reconstructing the contemporary history of urban development and stormwater infrastructure in an arid, urban catchment in the City of Scottsdale, Arizona, USA. We found that the relative importance to USN functioning of both network structure (geomorphology) and dynamics (spatial celerity pattern) changed with the spatial scale, with network geomorphology being more dominant at larger spatial scales. The importance of network geomorphology suggested that the structure of the USN itself could potentially serve as a stormwater control measure, for example, by enhancing flow dispersion. The temporal evolution of the USN revealed a sudden change in the hydrological functioning of the network, which seemed to be a consequence of the combined effects of patchy urban development and changes in network connectivity. The interactions between the urban spatial pattern, stormwater infrastructure, and surface runoff may result in threshold‐like behavior. A spatial multiscale approach to stormwater management may be beneficial to ensure that hydrological benefits at one scale do not cause unintended consequences at another. Overall, the retrospective modeling and network analysis approach used in this study may be useful for understanding emergent urban stormwater impacts.