Thursday, November 30, 2017

Natural Shoreline Case Study

A report published in November 2017 features the Surfers' Point Managed Shoreline Retreat project as an example of Natural Shoreline Infrastructure for adapting to sea level rise.  The report states:

Sea level rise and erosion are major threats to California’s coast, requiring solutions to preserve the many benefits a healthy coastline provides:  flood protection, recreation, habitat for wildlife, water quality and more. Seawalls and other engineered structures, are commonly installed in order to hold the shoreline in place and hold back the ocean; however, they ultimately make the situation worse in most cases by increasing erosion and thus causing already vulnerable shorelines to shrink more.
Natural shoreline infrastructure is an alternative that is more likely to preserve the benefits of coastal ecosystems while also maintaining coastal access.  

Five projects that spanned the California coast and represented different coastal settings and corresponding approaches were selected for the purposes of this report. From South to North these include:

  • Seal Beach National Wildlife Refuge Thin-layer Salt Marsh Sediment Augmentation Pilot Project,
  • Surfers’ Point Managed Shoreline Retreat Project 
  • San Francisco Bay Living Shorelines:Nearshore Linkages Project
  • Hamilton Wetland Restoration Project
  • Humboldt Coastal Dune Vulnerability and Adaptation Climate Ready Project

These case studies were designed to be useful examples for coastal planners, local governments, and others working on solutions and making decisions regarding climate-related coastal hazards.

Of these, Surfers' Point and Humboldt Dunes are the only projects implemented on the active coast, while the others are in bays and estuaries which are not directly affected by erosion by ocean waves.  And Surfers' Point remains the sole example of managed retreat in response to coastal erosion on a developed shoreline.

One key lesson from the Surfers' Point case study is: 

  • Restoration of the backshore is a more effective approach to re-establishing shore morphology with desired ecology, restoration, and ecosystem services than the more traditional approach of building the shore seaward.
The full report my be downloaded here: 

More information:

Reference:  Judge, J., Newkirk, S., Leo, K., Heady, W., Hayden, M., Veloz, S., Cheng, T., Battalio, B., Ursell, T., and Small, M. 2017. Case Studies of Natural Shoreline Infrastructure in Coastal California: A Component of Identi cation of Natural Infrastructure Options for Adapting to Sea Level Rise (California’s Fourth Climate Change Assessment). The Nature Conservancy, Arlington, VA. 38 pp