“Value at Risk from Sea Level Rise.”
Some low-lying California cities would be seriously affected by sea-level rise, but others would experience relatively few or even no impact if the ocean level rises by about 2 feet by the year 2100, a groundbreaking parcel-by-parcel study conducted for Smart Coast California concluded.
However, the report cautions that flooding would be a more serious concern in low-lying areas if coupled with powerful storms that have a 1% chance of occurring each year – a so-called “100-year storm.”
The report was unveiled at Smart Coast California’s (SCCa) recent virtual stakeholder meeting. It was conducted by Milliman, an independent consulting firm that works with organizations including the Federal Emergency Management Agency, the Urban Land Institute, and the National Association of REALTORS®.
Matt Chamberlain, a principal and consulting actuary for Milliman, walked nearly 100 online participants through the highlights of its study, “Value at Risk from Sea Level Rise.”
The study had two main purposes: to estimate the market value of residential properties at risk from sea-level rise and storm events, and to evaluate the feasibility of managed retreat as a response to climate change. It reviewed potential impacts to individual parcels in low-lying areas of Carlsbad, Coronado, Imperial Beach, the City of Santa Cruz, and the City of Santa Barbara using data from the U.S. Geological Survey’s Coastal Storm Modeling System and residential building, parcel, and assessment data from LightBox SmartFabric Professional.
Chamberlain said potential impacts were greatest in Coronado, especially the part of the city that lies on the sandy Silver Strand linking the main part of Coronado Island to Imperial Beach to the south. The study shows there would be virtually no impact from the 1.6-foot sea level rise alone, but roughly $649 million worth of residences would be flooded if that was coupled with a 100-year storm. A 6.6-foot rise in ocean levels would flood structures valued at $4.3 billion without a storm event. Putting the losses in to perspective, the city’s current budget for fiscal year 2022 to 2023 is just $107 million.
In nearby Imperial Beach, a 20-year storm event today would flood $50 million in residential building market value, while a 1.6-foot rise coupled with a 100-year storm would cause $137 million in flood damage.
Carlsbad, however, is not expected to experience any flooding even under the most extreme scenario considered of 6.6-foot sea level rise coupled with a 100-year storm. On the other hand, Santa Barbara could see 2.4% of its residential buildings flooded and Santa Cruz could see just 0.3% of its residences experiencing flooding.
Chamberlain said there is also considerable uncertainty about when different amounts of sea level rise would occur, so it would be helpful to think about the impact from different amounts of rise rather than trying to forecast when that might occur.
In addition, he said the state and local governments should standardize their assumptions and models so potential impacts on neighboring cities could be compared on an apples-to-apples basis.
SCCa Consultant Don Schmitz told stakeholders that the organization has been approaching the topic in a cooperative and productive way, and that the message is getting out that “we don’t just want to armor the coast.” But he also reiterated SCCa’s position that coastal communities should be looked at individually in terms of what level of protection is warranted.
“A one-size-fits-all approach is folly. The State Lands Commission recently affirmed that managed retreat wouldn’t take place at the ports of Los Angeles and Long Beach because there’s no place for them to retreat to, but our coastal communities are also important, both culturally and economically, and we need to find solutions to keep them.”
“We’re getting more granular as we learn and study more. We’d never gotten down to the parcel level before this study. That’s an essential component for smart coastal planning, and it’s the direction we’re trying to go forward with.”
He added that more studies will be needed at this level to fully account for potential impacts and costs of managed retreat compared to protection measure such as breakwaters, artificial reefs, dune replenishment and, in some cases, shoreline armoring.
However, the report cautions that flooding would be a more serious concern in low-lying areas if coupled with powerful storms that have a 1% chance of occurring each year – a so-called “100-year storm.”
The report was unveiled at Smart Coast California’s (SCCa) recent virtual stakeholder meeting. It was conducted by Milliman, an independent consulting firm that works with organizations including the Federal Emergency Management Agency, the Urban Land Institute, and the National Association of REALTORS®.
Matt Chamberlain, a principal and consulting actuary for Milliman, walked nearly 100 online participants through the highlights of its study, “Value at Risk from Sea Level Rise.”
The study had two main purposes: to estimate the market value of residential properties at risk from sea-level rise and storm events, and to evaluate the feasibility of managed retreat as a response to climate change. It reviewed potential impacts to individual parcels in low-lying areas of Carlsbad, Coronado, Imperial Beach, the City of Santa Cruz, and the City of Santa Barbara using data from the U.S. Geological Survey’s Coastal Storm Modeling System and residential building, parcel, and assessment data from LightBox SmartFabric Professional.
Chamberlain said potential impacts were greatest in Coronado, especially the part of the city that lies on the sandy Silver Strand linking the main part of Coronado Island to Imperial Beach to the south. The study shows there would be virtually no impact from the 1.6-foot sea level rise alone, but roughly $649 million worth of residences would be flooded if that was coupled with a 100-year storm. A 6.6-foot rise in ocean levels would flood structures valued at $4.3 billion without a storm event. Putting the losses in to perspective, the city’s current budget for fiscal year 2022 to 2023 is just $107 million.
In nearby Imperial Beach, a 20-year storm event today would flood $50 million in residential building market value, while a 1.6-foot rise coupled with a 100-year storm would cause $137 million in flood damage.
Carlsbad, however, is not expected to experience any flooding even under the most extreme scenario considered of 6.6-foot sea level rise coupled with a 100-year storm. On the other hand, Santa Barbara could see 2.4% of its residential buildings flooded and Santa Cruz could see just 0.3% of its residences experiencing flooding.
Chamberlain said there is also considerable uncertainty about when different amounts of sea level rise would occur, so it would be helpful to think about the impact from different amounts of rise rather than trying to forecast when that might occur.
In addition, he said the state and local governments should standardize their assumptions and models so potential impacts on neighboring cities could be compared on an apples-to-apples basis.
SCCa Consultant Don Schmitz told stakeholders that the organization has been approaching the topic in a cooperative and productive way, and that the message is getting out that “we don’t just want to armor the coast.” But he also reiterated SCCa’s position that coastal communities should be looked at individually in terms of what level of protection is warranted.
“A one-size-fits-all approach is folly. The State Lands Commission recently affirmed that managed retreat wouldn’t take place at the ports of Los Angeles and Long Beach because there’s no place for them to retreat to, but our coastal communities are also important, both culturally and economically, and we need to find solutions to keep them.”
“We’re getting more granular as we learn and study more. We’d never gotten down to the parcel level before this study. That’s an essential component for smart coastal planning, and it’s the direction we’re trying to go forward with.”
He added that more studies will be needed at this level to fully account for potential impacts and costs of managed retreat compared to protection measure such as breakwaters, artificial reefs, dune replenishment and, in some cases, shoreline armoring.
Milliman Report: |
Market Value at Risk from Sea Level Rise in selected California cities
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This is a large file (276 pages)
| Download Report Here |
Artificial Reefs
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SCIENTIFIC AND NEWS ARTICLES AND LITERATURE
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IMPROVE SURFING CONDITIONS
Artificial reefs can also be designed to improve surfing conditions in addition to protecting against coastal erosion: Catalog of Artificial Surf Reefs: Raised Water Research COST
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EXAMPLES OF ARTIFICIAL REEFS
CALIFORNIA
Port of San Diego, 2021
The Port of San Diego, in partnership with the California Coastal Conservancy and USFWS, has protected the Chula Vista Bayfront with 360 reef balls at an approximate cost of $960,000. The CCC approved the project in 2021 as a Port Master Plan Amendment. The artificial reef has shown good results in its early months.
San Clemente, 2019
210-acre artificially constructed kelp reef northward expansion of Wheeler North Reef (from San Clemente Pier nearly to Dana Point city limit) approved by the CCC (March 7, 2019, Item Th9B), constructed in 2020.
Rancho Palos Verdes, 2019
9-acre artificial rocky reef approved for construction off the Palos Verdes Peninsula by the CCC (May 9, 2019, Item Th10b), constructed in 2020.
El Segundo, 1993
The CCC approved Surfrider Foundation’s proposal for an artificial surfing reef as a mitigation measure for lost surfing resources (July 14, 1993).
Oceanside, 2021 [in progress, no approval yet]
The City of Oceanside’s Beach Sand Feasibility Study determined artificial reefs to be a highly effective adaptation option for inclusion in a future Local Coastal Program Amendment.
UNITED STATES
Miami Dade County, Florida
The county has deployed artificial reef structures, including reef balls, in nearly 30 sites as part of its Artificial Reef Program. The purpose is mainly for ecological and recreational diving benefits. In 2011 the U.S. Army Corps of Engineers approved a Finding of No Significant Impact for an artificial reef erosion control project with Miami-Dade County continuing planning through 2015 before the Surfrider Foundation killed the project through a PR campaign.
Artificial reefs in other Atlantic and Southern states serve ecological, recreational, and tourism purposes. Artificial reef breakwaters have been used in other countries to reduce shoreline erosion and improve surfing conditions
Staten Island, New York
Living Breakwaters has successfully established 2,400 linear feet of artificial reef structures off the South Shore of Staten Island to protect against erosion, storm damage, and enhance habitat. This concept was part of a winning proposal in the U.S. Department of Housing and Urban Development’s adaptation competition Rebuild by Design. It cost $107 million. https://stormrecovery.ny.gov/living-breakwaters-project-background-and-design Construction updates can be found at: https://stormrecovery.ny.gov/living-breakwaters-construction-updates
GLOBAL
Dominican Republic
The Gran Dominicus Reef (constructed in 1998) is a three-row reef ball submerged breakwater that protects the shoreline from erosion and has significantly increased beach width and elevation by an approximate 13 meters of added sandy shoreline (Harris, 2009).
Grand Caymen Island
A five-row reef ball submerged breakwater has stabilized and increased Seven Mile Beach (Harris, 2009).
Antigua
A five-row reef ball submerged breakwater reef provides diving tourism benefits and shoreline protection (Harris, 2009).
Bangladesh [temporary study, no longer in place]
A pilot project on the Kutubdia Island showed that an artificial oyster reef can grow in height quickly enough to keep pace with sea level rise and remain an effective shoreline protection solution.
Gold Coast, Australia
Narrowneck Reef and Palm Beach Reef were designed primarily for shoreline protection but have also improved surfing conditions. Narrowneck required a refurbishment due to post-installation sinking. The artificial reef was built upwards and again functions effectively.
Perth, Australia
Cables Reef is a successful artificial surfing reef.
Albany, Australia
Middleton Beach Reef is a successful artificial surfing reef.
CALIFORNIA
Port of San Diego, 2021
The Port of San Diego, in partnership with the California Coastal Conservancy and USFWS, has protected the Chula Vista Bayfront with 360 reef balls at an approximate cost of $960,000. The CCC approved the project in 2021 as a Port Master Plan Amendment. The artificial reef has shown good results in its early months.
San Clemente, 2019
210-acre artificially constructed kelp reef northward expansion of Wheeler North Reef (from San Clemente Pier nearly to Dana Point city limit) approved by the CCC (March 7, 2019, Item Th9B), constructed in 2020.
Rancho Palos Verdes, 2019
9-acre artificial rocky reef approved for construction off the Palos Verdes Peninsula by the CCC (May 9, 2019, Item Th10b), constructed in 2020.
El Segundo, 1993
The CCC approved Surfrider Foundation’s proposal for an artificial surfing reef as a mitigation measure for lost surfing resources (July 14, 1993).
Oceanside, 2021 [in progress, no approval yet]
The City of Oceanside’s Beach Sand Feasibility Study determined artificial reefs to be a highly effective adaptation option for inclusion in a future Local Coastal Program Amendment.
UNITED STATES
Miami Dade County, Florida
The county has deployed artificial reef structures, including reef balls, in nearly 30 sites as part of its Artificial Reef Program. The purpose is mainly for ecological and recreational diving benefits. In 2011 the U.S. Army Corps of Engineers approved a Finding of No Significant Impact for an artificial reef erosion control project with Miami-Dade County continuing planning through 2015 before the Surfrider Foundation killed the project through a PR campaign.
Artificial reefs in other Atlantic and Southern states serve ecological, recreational, and tourism purposes. Artificial reef breakwaters have been used in other countries to reduce shoreline erosion and improve surfing conditions
Staten Island, New York
Living Breakwaters has successfully established 2,400 linear feet of artificial reef structures off the South Shore of Staten Island to protect against erosion, storm damage, and enhance habitat. This concept was part of a winning proposal in the U.S. Department of Housing and Urban Development’s adaptation competition Rebuild by Design. It cost $107 million. https://stormrecovery.ny.gov/living-breakwaters-project-background-and-design Construction updates can be found at: https://stormrecovery.ny.gov/living-breakwaters-construction-updates
GLOBAL
Dominican Republic
The Gran Dominicus Reef (constructed in 1998) is a three-row reef ball submerged breakwater that protects the shoreline from erosion and has significantly increased beach width and elevation by an approximate 13 meters of added sandy shoreline (Harris, 2009).
Grand Caymen Island
A five-row reef ball submerged breakwater has stabilized and increased Seven Mile Beach (Harris, 2009).
Antigua
A five-row reef ball submerged breakwater reef provides diving tourism benefits and shoreline protection (Harris, 2009).
Bangladesh [temporary study, no longer in place]
A pilot project on the Kutubdia Island showed that an artificial oyster reef can grow in height quickly enough to keep pace with sea level rise and remain an effective shoreline protection solution.
Gold Coast, Australia
Narrowneck Reef and Palm Beach Reef were designed primarily for shoreline protection but have also improved surfing conditions. Narrowneck required a refurbishment due to post-installation sinking. The artificial reef was built upwards and again functions effectively.
Perth, Australia
Cables Reef is a successful artificial surfing reef.
Albany, Australia
Middleton Beach Reef is a successful artificial surfing reef.