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Planning for the Future of California’s Coastline

Sea level rise is not evenly distributed globally. The coastline of western North America has not faced the same level of challenges of the Atlantic and Gulf Coasts but addressing and adapting to sea level rise in California is a top priority. The 2015 Coastal Symposium united leaders in coastal resiliency planning from municipalities, state and federal agencies, academia, and the private sector. Our Director of Ecology and California native, Nick Buhbe, attended the symposium and shares his top take-aways ranging from notable coastal projects to adaptive planning tools already in use.

Leading researcher and consultant, Dr. Reinhard E. Flick of Scripps Institution of Oceanography, shared his extensive research in coastal processes including sea level rise (SLR), effects of tides and storm surge, and coastal erosion.

  • The Keeling Curve demonstrates a 25% increase in atmospheric carbon dioxide (CO2) during the last 50 years. We know that this represents a continuation of CO2 releases which dramatically increased following the Industrial Revolution, and that the rate of increase is unprecedented.
    • As we have no reference of an increase of this magnitude in the geologic record, the effects are not predictable.
    • However, we do know that effects are being realized, and it is a question of when the effects will be felt, not whether the effects will occur.

Based on what is known from studies of the polar regions, there is already 30-40 feet of SLR which “baked in” to the climate change which is unavoidable; the question is how fast will the SLR be realized.

  • SLR will not be the direct result of the much publicized breakup of ice shelves (such as Larsen B in Antarctica), as ice shelves are essentially floating and act as barriers to glacier flow from the land into the sea. Rather, without the protection of ice shelves, glaciers will flow into the sea and sea levels will increase.

Changes will not be overnight, but the effects are likely to be driven by chance coincidence of storm surges and high tide events.  At low tide, effects of storm surges or large wave events will be relatively muted.  However, when the high wave events or storm surges occur over long periods of time or match with “king tides,” the effects will be significant as areas not usually inundated become flooded.

  • SLR effects will be particularly pronounced when hard structures, such as seawalls, or natural features such as cliffs, prevent the beach from moving upward. In such cases, the likely effect will be the acceleration of erosion (if not in the direct area, then in adjacent areas) and potentially dramatic changes to the character of the beach itself.
  • Stilwell Hall (Monterey County, California) – an example of natural correction of a shoreline when hard backshore structures are removed.
    • Constructed in 1940s, the abandoned building was torn down in 2003 before it slid into the ocean as the shoreline armoring couldn’t be maintained effectively.
    • Check out the incredible before and after photos taken by Kenneth & Gabrielle Adelman.

The California Coastal Commission’s Draft Sea Level Rise Policy Guidance is a framework addressing sea level rise in Local Coastal Programs (LCPs) and Coastal Development Permits (CDPs). Specifically, it details how the State intends to apply the California Coastal Act, the primary coastal management law to address land use, public access and recreation, and the protection of coast and ocean resources.

  •  Resiliency planning and adaptation projects in California are especially complex with the extensive infrastructure and resources located along the coast. Some of the largest cities, Los Angeles, San Diego, and San Francisco are directly on the coast and do not have the option to pick up and retreat inland.
    • Our major interstate freeways travel up and down the coastline.
    • California’s coastal and ocean economy: $40B (NOEP 2010).
    • Sea levels are increasing the fastest at Humbolt Bay in Northern California.
  • It is likely that many of the coastal resiliency projects in California will be implemented on a local scale by municipalities–this means that some areas will elect to use natural barriers whereas others may choose to build hard structures such as seawalls.

Following sessions presented case studies of Local Seas Level Rise Adaptation Planning Projects funded by the California Coastal Conservancy, Coastal Commission and Ocean Protection Council. Key take-aways from the case studies:

Where we are: 
We’ve built many models and used them and other tools to inform vulnerability.

Where were going:
Vulnerability studies and adaptation pathway analyses have been used to develop site-specific projects, which have been implemented and are in the process of being evaluated for lessons learned.

Of particular interest to Great Ecology’s coastal scientists was the Thin Layer Salt Marsh Sediment Augmentation Project.

  • The US Fish & Wildlife Service is spraying a thin layer of sediment over 10-acres of a low salt marsh within the Seal Beach Natural Wildlife Reserve.
  • The project will monitor the physical and ecological responses of the marsh to the additional sediment over a 5 year period.
  • Why it matters: if the project successfully document effectiveness of the sediment spray strategy in combating sea level rise, it is a natural SLR protection measure applicable to important rare habitats prioritized for conservation.

We know successful resiliency projects may include artificial reefs, tidal marsh enhancements, living or soft shorelines, and dunes. However, there are still a few big questions remaining:

  • How do we get sediments from land-locked retention structures (dams and flood control structures) to beaches to improve resiliency?
  • An Orange County pilot study by the U.S. Army Corps of Engineers at the Prado Dam is currently under consideration to study one application of this idea.

  • How do coastal managers engage the public to bring this to the forefront at the city, state, and federal levels?
  • Presenters advised although SLR and climate change are often met with skepticism, communicating the importance of protecting infrastructure and responsible taxpayer fund management has been well received.

As we know sea level rise and resiliency planning and adaption are highly complex. Currently in California, pilot projects are being implemented at the local levels, and the lessons learned from these first steps will greatly inform what tools can be effectively implemented to minimize catastrophic effects.

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