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Clusters of community exposure to coastal flooding hazards based on storm and sea level rise scenarios—implications for adaptation networks in the San Francisco Bay region

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Sea level is projected to rise over the coming decades, further increasing the extent of flooding hazards in coastal communities. Efforts to address potential impacts from climate-driven coastal hazards have called for collaboration among communities to strengthen the application of best practices. However, communities currently lack practical tools for identifying potential partner communities based on similar hazard exposure characteristics. This study uses statistical cluster analysis to identify similarities in community exposure to flooding hazards for a suite of sea level rise and storm scenarios. We demonstrate this approach using 63 jurisdictions in the San Francisco Bay region of California (USA) and compare 21 distinct exposure variables related to residents, employees, and structures for six hazard scenario combinations of sea level rise and storms. Results indicate that cluster analysis can provide an effective mechanism for identifying community groupings. Cluster compositions changed based on the selected societal variables and sea level rise scenarios, suggesting that a community could participate in multiple networks to target specific issues or policy interventions. The proposed clustering approach can serve as a data-driven foundation to help communities identify other communities with similar adaptation challenges and to enhance regional efforts that aim to facilitate adaptation planning and investment prioritization.
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ORIGINAL ARTICLE
Clusters of community exposure to coastal flooding hazards based
on storm and sea level rise scenariosimplications for adaptation
networks in the San Francisco Bay region
Michelle A. Hummel
1
&Nathan J. Wood
2
&Amy Schweikert
2
&Mark T. Stacey
1
&Jeanne Jones
2
&Patrick L. Barnard
3
&
Li Erikson
3
Received: 20 February 2017 /Accepted: 28 November 2017 /Published online: 7 December 2017
#Springer-Verlag GmbH Germany, part of Springer Nature 2017
Abstract
Sea level is projected to rise over the coming decades, further increasing the extent of flooding hazards in coastal communities. Efforts
to address potential impacts from climate-driven coastal hazards have called for collaboration among communities to strengthen the
application of best practices. However, communities currently lack practical tools for identifying potential partner communities based
on similar hazard exposure characteristics. This study uses statistical cluster analysis to identify similarities in community exposure to
flooding hazards for a suite of sea level rise and storm scenarios. We demonstrate this approach using 63 jurisdictions in the San
Francisco Bay region of California (USA) and compare 21 distinct exposure variables related to residents, employees, and structures for
six hazard scenario combinations of sea level rise and storms. Results indicate that cluster analysis can provide an effective mechanism
for identifying community groupings. Cluster compositions changed based on the selected societal variables and sea level rise
scenarios, suggesting that a community could participate in multiple networks to target specific issues or policy interventions. The
proposed clustering approach can serve as a data-driven foundation to help communities identify other communities with similar
adaptation challenges and to enhance regional efforts that aim to facilitate adaptation planning and investment prioritization.
Keywords Climate change .Adaptation .Flooding .Exposure .Cluster analysis
Introduction
Coastal communities in low-lying areas are continually vul-
nerable to flooding, and future threats are likely to increase
due to the influence of projected sea level rise (SLR) (Deconto
and Pollard 2016), potentially displacing millions of people
and causing up to $1 trillion in damages (Nicholls 2004;
Hinkel et al. 2013). Projected increases in sea level can lead
to more frequent and persistent nuisance flooding (Sweet et al.
2014), permanent inundation of low-lying areas, and increases
Editor: Christopher Reyer.
Electronic supplementary material The online version of this article
(https://doi.org/10.1007/s10113-017-1267-5) contains supplementary
material, which is available to authorized users.
*Michelle A. Hummel
mhummel@berkeley.edu
Nathan J. Wood
nwood@usgs.gov
Amy Schweikert
aschweikert@usgs.gov
Mark T. Stacey
mstacey@berkeley.edu
Jeanne Jones
jmjones@usgs.gov
Patrick L. Barnard
pbarnard@usgs.gov
Li Erikson
LErikson@usgs.gov
1
Civil and Environmental Engineering, University of California,
Berkeley, 205 OBrien Hall, Berkeley, CA 94720, USA
2
Western Geographic Science Center, U.S. Geological Survey, Menlo
Park, CA, USA
3
Pacific Coastal and Marine Science Center, U.S. Geological Survey,
Santa Cruz, CA, USA
Regional Environmental Change (2018) 18:13431355
https://doi.org/10.1007/s10113-017-1267-5
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... How sea-level rise will affect the amount of inundated land and infrastructure capacity varies over space and time. For example, Hummel et al. (2018b) grouped SF Bay communities according to similar vulnerabilities, with some communities facing high levels of flooding, while also featuring critical infrastructure facilities and lower socioeconomic status. Such communities may be considered disadvantaged and require consideration from an equity and environmental justice standpoint (e.g., Felsenstein and Lichter 2014). ...
... Engaging disadvantaged communities is further constrained by a lack of capacity to effectively participate in planning, more attention being paid to other short-term priorities, and a history of distrust with political actors. Like in many other coastal regions, disadvantaged communities in the Bay Area are disproportionately exposed to flood risks (Hummel et al. 2018b). ...
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... We did not account for changes in socioeconomic development or population distribution over time (57), which could bias results depending on their future trajectory. While our analysis focused on property replacement values, protection of vulnerable populations may be a priority for communities but may be undervalued through traditional property value-based analyses such as the one presented here (58,59). ...
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Significance As sea levels rise, coastal cities will rely on shoreline protection strategies such as levees and seawalls to mitigate flooding. Although these strategies provide local flood-reduction benefits, they can increase inundation along other shorelines within the same estuary or bay. Using hydrodynamic and economic models, we quantify previously unmeasured regional economic damages (up to $723 million per flood event) that result from the protection of individual shoreline segments in San Francisco Bay, CA. We also highlight and quantify opportunities to alleviate regional flood damage through strategic floodwater storage in low-lying areas. Integrating the findings into coordinated planning efforts that account for the regional impacts of local shoreline actions could provide opportunities to reduce shared risk in coastal regions globally.
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