Los Angeles County Vulnerability Assessment
Assessing the Geographic Variability in Vulnerability to Climate Change and Coastal Hazards in Los Angeles County, California
An introduction to the NCCOS Framework:
Coastal communities are increasingly vulnerable to climate effects, such as sea level rise and coastal erosion. To address these and other changing coastal risks in Los Angeles (L.A.) County, we are applying the National Centers for Coastal Ocean Science’s ( NCCOS ) Integrated Vulnerability Assessment Framework to this densely populated and highly urbanized region, along with further spatial and economic analyses. This work will provide information to better protect, advance, and manage climate change impacts within local communities.
The NCCOS Integrated Vulnerability Assessment Framework steps are outlined below. Building upon previous work done in the Chesapeake Bay, the Framework was applied to L.A. County, California. The overarching goals of the project were to: 1) provide partners with the ability to more easily understand the complexities of overall vulnerability and risk within their region, thereby leading to informed management action; and 2) expand upon previous iterations of the Framework in a new geography with variability in demographics, ecology, and climate concerns.
Steps 1-2: Partner engagement and indicator development
Step 1: Engage local partners and stakeholders to identify aspects of vulnerability and climate-driven risk within the study area. Interactive exercises encouraged partners and stakeholders to prioritize vulnerabilities and risks of most concern within L.A. County and compare variations of these rankings.
Exercises also asked partners and stakeholders to prioritize analyses of interest, as well as particular geographies of interest or concern.
Areas of concern to local partners are mapped to the right. Hover and click on arrows for more detail.
Step 2: Develop indicators and indices for each vulnerability and risk.
Vulnerability is defined as the susceptibility of resources, infrastructure, and populations to be adversely impacted by environmental hazards or variables.
Risk is defined as a coastal or climate-driven hazard that has the potential to cause damage to, or result in the loss of, coastal resources, built environments, and coastal populations.
Drawing upon feedback derived from partner exercises, findings from the team’s gap analysis, and expert opinion, the project team focused on the following suite of climate-driven risks: coastal flooding, stormwater flooding, erosion, drought, heat, and wildfire.
Steps 3-5: Assessing risk and vulnerability
Vulnerability
Step 3: Assess social vulnerability, structural vulnerability, and natural resource vulnerability within the study area. Data were collected from a range of available sources, and each vulnerability profile was measured relative to other block groups within the study area.
For example, social vulnerability was assessed using a modified Social Vulnerability Index methodology, and the resulting map is shown here. For more details on this approach, please see the link below or download our full technical report.
Risk
Step 4: Assess risks within the study area. These data were also collected from a range of available sources, and each risk profile was measured relative to other block groups within the study area.
For example, the wildfire risk profile used the Cal Fire dataset from the California Department of Forestry and Fire Protection, and the resulting map is shown here. For more information on the data used, please see the link below.
Vulnerability intersected with Risk
Step 5. Intersect vulnerability and risk profiles. Bivariate choropleth maps (i.e. maps that depict two variables at once) were created to easily compare vulnerability and risk to one another.
For example, social vulnerability is shown with wildfire risk to the right. These maps serve as a visual tool to depict areas where high vulnerability intersects with high risk. Such maps can help prioritize actions and aid in decision making when considering particular aspects of vulnerability and risk.
Step 6: Engage local partners and stakeholders for prioritization of adaptation areas and next steps to mitigate climate-driven impacts.
Areas that share multiple vulnerabilities and/or risks create the need for adaptation action in the face of a changing climate, but they also present an opportunity to develop and implement innovative strategies that mitigate multiple concerns across multiple sectors at once.
The rest of this story map focuses on two risks of primary concern in L.A. County, as identified by project partners: wildfire risk and flooding risk.
Wildfire Risk in L.A. County
Wildfire is not a new threat to L.A. County and its inhabitants, but climate change and development into previously ‘natural’ areas, or areas that were once allowed to burn without disrupting human settlements, have exacerbated wildfire risk. White outlines represent developed areas as of 2016. Scroll to move forward through time from the 1900s to Present.
1900s
1910s
1920s
1930s
1940s
1950s
1960s
1970s
1980s
1990s
2000s
2010s to present
Cumulative 1990s-present
The map to the right shows a snapshot of peripheral development by age of structure, where light blue is development through 1950, dark blue is development from 1950 to 1980, purple is development from 1980 to 2000, and pink is development from 2000 on. The inset map shows development slowly encroaching on historically undeveloped land (and also the smoke from the 2017 Rye fire). These areas where development encroaches upon undeveloped wildlands and vegetation, often called the wildland–urban interface, are key in zones where environmental conflict occurs.
For up to date data on current wildfires, please see the California Department of Forestry and Fire Protection (CAL FIRE) incident dashboard by clicking the link below.
Wildfire risk intersected with social and structural vulnerability
In the following maps, wildfire risk and social vulnerability are highest in a few large block groups in the northeastern portion of the County, as well as in a few pockets in central L.A. A similar trend is shown for structural vulnerability, where structural vulnerability and wildfire risk are highest along the periphery of urban areas.
Flooding Risk in L.A. County
Partners were also interested in coastal flooding impacts. Coastal flooding potential used projections by USGS’s Coastal Storm Modeling System ( CoSMoS ) ( Barnard, et al., 2017 ) as determined for a 100-year storm event at year 2100 sea level under relatively high continued emissions estimates and high risk aversion ( California Natural Resources Agency and California Ocean Protection Council, 2018 ; Kopp et al., 2014 ).
This long term-high risk scenario is shown to the right, and is focused on the Marina del Rey area. Feel free to scroll around and interact with this map.
The map also displays the long term-high risk scenario, but is focused on the Malibu area. Feel free to scroll around and interact with this map as well.
Following initial implementation of the Framework in L.A. County, partners identified the need for an additional coastal geography. A 10-mile coastal band geography was chosen (shown below). This map shows the near term-low risk coastal flooding scenario on the left and the long term-high risk scenario on the right. (Note: The near term-low risk scenario displays coastal flooding potential by USGS's CoSMoS as determined for an annual storm event at year 2040 sea level under relatively high continued emissions estimates and low risk aversion.) Feel free to drag the panel back and forth to view the differences between these two flooding scenarios.
The following interactive maps also show the smoke from the 2017 Rye fire, which highlights the possibility of multiple risks impacting L.A. at any given time.
Near Term-Low Risk Scenario (left) and Long Term-High Risk Scenario (right)
Social vulnerability for the same 10-mile coastal band in L.A. County is shown to below, with areas of highest vulnerability relative to other parts of the region shown in darker shades of red.
Long Term-High Risk Scenario (left) and Social Vulnerability (right)
Opportunities and Applications
Additional methods, analysis, and results comparing various risks and vulnerabilities within L.A. County can be found in the full technical report, available through our project page linked below. The resulting maps and data from this project can be used by local partners and stakeholders to establish adaptation priority areas for the coastal and climate-driven risks explored in this research. While many local communities in L.A. County already have sustainability or climate action plans in place (e.g., Cities of L.A., Long Beach, Hawthorne, Santa Monica), the NCCOS assessment may provide information for determining the locations for planned adaptation activities and goals. For communities that are in the process of developing these plans, this assessment and its underlying data may aid these efforts.
Most of this project's final maps combined a single risk with a single vulnerability, but users may find it informative to overlay two risks or two vulnerabilities. Areas that share multiple aspects of vulnerability and/or risk create the need for adaptation action in the face of a changing climate, but they also present an opportunity to develop and implement innovative strategies that mitigate multiple concerns across multiple sectors at once. This flexibility allows for management action based on various time horizons, management needs, levels of political and public support, and availability of funding.
Please visit our project page for the final report and more information about this research by clicking the link below.
The authors would like to extend our appreciation to the project team for its contributions and thoughtful input throughout the many stages of this project. We are especially grateful to our external project partners, namely Phyllis Grifman, Linda Chilton, and Marika Schulhof at University of Southern California Sea Grant, Melissa Rosa formerly at NOAA’s Office for Coastal Management – West Coast Region, and Nick Sadrpour and Alyssa Newton Mann (both formerly with USC Sea Grant). Without your local and regional expertise, assistance, and feedback, this project would not have been possible.
Project Team: Chloe Fleming (1), Seann Regan (1), Amy Freitag (4), Heidi Burkart (1), Melissa Rosa (2), Phyllis Grifman (3), Nick Sadrpour (3), and Theresa Goedeke (4)
1 CSS, Inc., under contract to NOAA/National Ocean Service/National Centers for Coastal Ocean Science
2 CSS, Inc., under contract to NOAA/National Ocean Service/Office for Coastal Management
3 University of Southern California Sea Grant
4 NOAA/National Ocean Service/National Centers for Coastal Ocean Science
