1. Sea Level Rise Adaptation Strategy for
Oceanside, CA
October 17, 2016
By Emily Phan

2. I. EXECUTIVE SUMMARY
The city of Oceanside is situated along the California coast between the major
urban areas of San Diego and Los Angeles, serving as one of the major intercity
transportation stops. The city has grown rapidly into an arts and cultural hub as well as a
booming beach town, drawing families, surfers, and tourists to the area. Much of the
economic activity and livelihood in the area depends on the tourism brought in for the
beautiful beaches, wildlife, and and new city developments.​1​
The second largest
employment industry in Oceanside is retail (over 25%) and this is dominated by the large
variety of small shops along the harbor, weekly farmer’s markets, and recreational water
activities (such as surfing, deep-sea fishing, whale watching, kayaking, and cruises)
(Figure 1). Within the city also exists sensitive lagoons, wetlands, and river habitats of
protected species in danger of flooding.
The economic dependence on the coast as well
as heavy investment into residential growth
within Oceanside warrants coastal protection
plans and risk evaluations for the projected sea
level rise in the next 30 years. The city has
recognized the need to create a Climate Action
Plan and incorporate reinforcements into future
developments, but has not made any changes to
upcoming developments. The Scripps Institute of
Oceanography has generated tidal forecasts
based off ocean data along the Oceanside coast,
estimating a possible sea level rise of up to
9.8-10.5 ft by 2050 (Figure 2). This adaptation
strategy will assess the vulnerability of these
affected areas and make recommendations for
the Oceanside City Council.
II. VULNERABILITY ASSESSMENT
This vulnerability assessment determines what areas may be subjected to
flooding, inundation, and major community hindrances. These categories each have
varying levels of risk depending on the speed of sea level rise. Based on data from the
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3. U.S. National Research Council, the likelihood of a 1 ft sea level rise by 2050 is almost
100%.​4
Table 1: Locations and their estimated vulnerability based off flooding data obtained from Climate Central
and the U.S. National Research Council
Location Vulnerability
Wetlands Very high chance of flooding and erosion
Buena Vista Lagoon & San Luis Rey River Very high chance of flooding, erosion,
runoff.
Residential Areas Medium in locations near bodies of water.
Need for relocation within next 30 years.
Commercial Areas Medium along the beach, high along the
harbor.
Transportation Lines Very low chance of flooding and
inundation.
Pedestrian Roads Very low chance of flooding and
inundation, low near beach.
Open Spaces and Parks Very low chance of flooding in areas close
to lagoon.
Beaches and Sandbar Very high chance of erosion and flooding.
III. RISK ASSESSMENT
Risk assessment will evaluate how the sea-level rise or erosion will impact the
previously listed vulnerable areas.
a. Wetlands
The species inhabiting the wetlands are at the highest risk and also most
likely going to be impacted within the next 30 years. Figure 2 demonstrates
that even a 1 ft sea level rise will lead to major loss of the wetlands.
Wetlands are crucial barriers to the lagoon because it protects the animal
and plant species living in the lagoon from waves, flooding, and erosion.​7
Wetlands also serve major environmental purposes such as natural
cleaning and cycling out of pollutants in the lagoon.
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4. b. Buena Vista Lagoon & San Luis Rey River Habitats
Figure 3 shows the current elevation of the lagoon (above sea level) and
Figure 4 shows that the lagoon will be below the water level after a sea level
rise. This means that during coastal storms or flash flooding, the lagoon will
definitely be susceptible to flooding. This will cause flooding within the city
as well. Improper stormwater drainage and irrigation will cause major runoff
problems into the Buena Vista Lagoon and San Luis Rey River then,
subsequently, into the Pacific Ocean.​2​
This can easily cause major health
issues if sewage systems also get flooded. Oceanside is also a partially
agricultural city so the topsoil and alluvium will easily be eroded.​6
Impacted animals: California Least Tern, Elegant Tern, Light-footed Clapper Rail,
Yellow-breasted Chat, Cooper’s Hawk 6
Impacted plants: Sticky Dudleya 6
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5. c. Residential Areas
Homes along the beach, situated on the Oceanside sandbar (see Figure 2)
and near the lagoon are susceptible to flooding and erosion based on the
projections made, particularly homes by the wetlands, south harbor, and
San Luis Rey River although risk is relatively small. The impacted population
is mostly upper middle class with properties valued at $10-100M.​3
d. Commercial Areas
Since a significant amount of economic activity are the shops along the
beach and on the harbor, this would could potentially cause major economic
setbacks in the city and high unemployment.​2​
Figure 2 shows a high chance
of inundation of huge sections of the harbor after a 1 ft rise.
e. Transportation Lines
The largest intercity railroad through Oceanside runs parallel to the coast
and is situated approximately 650 ft away from the beach. The sea level rise
should not heavily impact the railroad.​1​
However, major flooding could
cause slow downs or delays although the risk is extremely low.
f. Pedestrian Roads
Roads near the beach may be closed on high tide seasons or flooding. The
south harbor would no longer be able to support pedestrians based off
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6. Figure 2.
g. Open Spaces and Parks
Hosp Grove Park on the north end has a very low risk for flooding.
Continued sea level rise may cause more problems.
h. Beaches and Sandbar
The coast is definitely going to face high levels of erosion from a 1 ft sea
level rise. Most of the sandbar protecting the harbor will be gone which
could potentially lead to higher rates of coastal erosion as well. Figure 2
shows ⅓ of the beach lost to the ocean at a very high possibility. This will
also impact the recreational water activities business because the sandbar
will no longer provide a protected coastal area for the harbor.
After the evaluation of this coastal zone, the Oceanside City Council should highly
prioritize reinforcements for the harbor as well as protection for the wetlands. The harbor
is a huge economic hub in Oceanside for both tourists and residents. It provides
employment and business and thus should be protected to maintain status quo. The
wetlands should be protected because of the many environmental benefits its provides,
both reinvigorating and protecting the land and animals around it. It would also prevent
major problems that could arise out of inner city flooding and displacement of people
from their homes.
IV. ADAPTATION PLAN
The adaptation strategies recommended will seek to minimize damages from the
rising tides as well as reinforcements and accommodations for future developments
along the coast. The first developments will be focused on minimal intrusion of the
natural habitats along the coasts and protection of the shoreline. This will minimize
flooding and erosion issues further in the city. Strategies are derived from the Sea Level
Rise Adaptation Strategy for San Diego Bay prepared by ICLEI-Local Governments for
Sustainability.
a. Seawall - Widened/Stepped
The main appeal of Oceanside is its development as a beach city and so a seawall
with steps all along the coast will allow residents and tourists to enjoy continued
access of the beach while protecting the beachside properties from waves. This
option is better than a levee because it is safer for surfers and others in the water
during high tides. If the expected rate of sea level rise increases, the alternative is
the retaining seawall although not favorable due to limiting beach access. This will
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7. mainly be implemented on beach areas.
b. Detention basins/Upland Floodplains
Along the inner borders of the lagoon the city should develop mini basins
alongside the lagoon. This has the potential to expand habitats of the lagoon and
also create areas to collect stormwater to prevent flooding. The water collected
could potentially replenish groundwater sources or filter into the wetlands
naturally. The large open parks and natural reserves in the area will allow this to be
done without major relocation of residents in the area. In addition, since the basins
will be natural barriers, they will not prevent animals from migrating into different
areas.
c. Bioinfiltration/Stormwater Park and Irrigation channels
The wetland area bordering the beach is extremely sensitive to rising sea water.
This environment will naturally react by retreated further inland in response to
changing water levels and salinity.​7​
Since this area is most susceptible to flooding,
multiple natural water pockets should be built at the front of the wetlands to slow
down the inflow of seawater. There should be large areas of vegetation in between
the stormwater channels that can protect the area against erosion and flooding.
As a back up, there should also be irrigation channels from the stormwater park
that can direct the seawater into less vulnerable areas on the coast such as the
northern coast of the city.
d. Artificial Erosion Control
Much of the top layer of soil in Oceanside is alluvium and topsoil thus can easily be
eroded. To protect cliff side areas, vegetation should be restored to help hold
down soil. If this is not possible, these area should be fenced off a prevent further
human traffic on the area to strain the cliffs. The top layer of soil could also be
replaced by more compact soil or granite if there are future developments in the
area.
e. Elevated Structures
The the Oceanside harbor being an important part of the city’s commerce, the
harbor should be renovated with higher elevation (similar to a pier) so that they
when the sea level rises, the water will not permanently flood all the businesses.
f. Relocation & Withdrawal
If the previously listed accommodations are unable to mitigate flooding and
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8. erosion risks, the City of Oceanside should halt developments along the coast and
Buena Vista Lagoon and relocate people living in the area if possible.
V. RESOURCES
1. "City of Oceanside Concierge Manual." ​City of Oceanside, CA. City of Oceanside:
Economic Development, 2015. Web. 17 Oct. 2016.
<​https://www.ci.oceanside.ca.us/visitors/tourist.asp​>.
2. Torti Gallas and Partners, INC. “Coast Highway Visioning Strategic Plan.” ​City of
Oceanside, CA, Oceanside Visioning Coast Highway, 15 Apr. 2009.
<​https://www.ci.oceanside.ca.us/civicax/filebank/blobdload.aspx?blobid=24606​>.
3. Stamen Design. “Risk Zone Map.” ​Surging Seas, Climate Central, Mar. 2014.
<​http://ss2.climatecentral.org/?bbox=33.3147964,-117.414539089,33.1379836,-1
17.220690992&label=oceanside#13/33.2264/-117.3176?show=satellite&projectio
ns=0-rcp85-slr&level=3&unit=feet&pois=hide​>.
4. Stamen Design. “Risk Finder.” ​Surging Seas, Climate Central, 2016.
<​http://riskfinder.climatecentral.org/place/oceanside.ca.us?comparisontype=plac
e&forecastname=basic&forecasttype=nrc_low&level=3&unit=ft#threat-forecast​>.
5. San Diego County and City of Oceanside, California. Melrose Drive Extension.
Geological Reconnaissance. N.p.: Geocon Incorporated, n.d. ​City of Oceanside, CA.
Project Design Consultants, 4 Nov. 2002. Web. 17 Oct. 2016.
<​http://www.ci.oceanside.ca.us/civicax/filebank/blobdload.aspx?blobid=22893​>.
6. Mock, Patrick, and Wayne Spencer. “Subarea Plan.” ​City of Oceanside, CA, URS
Corporation &Amp; Conservation Biology Institute, July 2007.
<​https://www.ci.oceanside.ca.us/gov/dev/planning/subarea.asp​>.
7. ICLEI-Local Governments for Sustainability USA. The San Diego Foundation.
Tijuana River National Estuarine Research Reserve - Coastal Training Program. ​Sea
Level Rise Adaptation Strategy for San Diego Bay. ICLEI-Local Governments for
Sustainability, Jan 2015. Web. 17 Oct. 2016.
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