Natural Infrastructure for Coastal Adaptation to Sea Level Rise

The 2015 “The Baylands and Climate Change: What We Can Do” report, written with over 200 scientists, government officials, and resource managers, proposes a new approach to manage the challenge of sea level rise in San Francisco Bay: work with nature, rather than against it.

Natural infrastructure” can be used to take advantage of natural processes to protect homes, businesses, and shoreline communities from coastal flooding while cost-effectively providing other benefits such as water filtration, habitat, and recreation and requiring low maintenance and replacement costs.

What is Natural Infrastructure?

Natural infrastructure, also referred to as “green infrastructure”, mimics natural systems or restores natural processes to provide a service, such as shoreline protection.

Wetland, oyster bed, and dune features can increase coastal resilience to sea level rise and provide shoreline protection by:

 

  • buffering from storms and flooding
  • decreasing wave energy and run-up
  • slowing water movement and increasing infiltration
Multi-benefits: Other important benefits are provided continuously during times shoreline protection is not needed, such as water filtration, habitat, and recreation. Cost-effective: These natural features do not require costly repairs or replacement and the multiple benefits these features provide create additional value.

Case Studies from San Francisco Bay

Here, we present case studies of natural infrastructure techniques implemented in San Francisco Bay that enhance coastal resilience to sea level rise while providing additional natural benefits, including:

  • Living shorelines
  • Marsh mounds
  • Habitat transition ramps
  • Managed retreat

These case studies demonstrate the techniques and lessons learned from pilot projects to aid in the design, planning, and implementation of future natural infrastructure climate adaptation projects.

 

San Francisco Bay Living Shorelines Project

Feature: Living Shorelines

Establishing oyster and eelgrass beds to enhance shoreline protection and provide habitat for wildlife

 

Sears Point Restoration Project 

Feature: Marsh Mounds

Reclaiming a wetland and incorporating natural features that will mitigate and adapt to changing conditions

 

Sonoma Creek Enhancement Project

Feature: Habitat Transition Ramps

Enhancing a degraded wetland to maximize habitat, adaptation, and flood-protection goals

Opportunities and Applications of Natural Infrastructure for Coastal Resiliency

New Techniques Tested

Wastewater Treatment at Oro Loma in San Lorenzo Photo by Vivian Reed

At Oro Loma Wastewater Treatment Plant, 10 acres of degraded wetlands adjacent to the plant have been converted to an outdoor laboratory as a pilot project to test the ability of wetlands to purify secondarily treated water, re-connect treated water with the bay, and replace aging infrastructure vulnerable to sea level rise. The East Bay Discharge Authority began construction in spring 2015 and results from water quality monitoring will provide information on the success of this strategy as a green infrastructure alternative.

Managed Retreat at Breuner Marsh in Richmond

In the design for a newly restored Breuner Marsh, the East Bay Regional Park District is using natural infrastructure to protect park assets by incorporating “managed retreat” into its planning design, allowing the marsh to migrate inland as sea level rises. The strategy will generate benefits that include storm buffering and improved wildlife habitat.

Future Research and Applications

  • Techniques and lessons learned from these case studies can be used to inform project partners interested in incorporating natural resiliency features in their design for coastal adaptation to sea level rise.
  • Long-term monitoring of these case studies should be continued to track their effectiveness.
  • Pilot projects in more locations with differing environments are needed to test the application of these natural infrastructure strategies on other shoreline types around the bay.
  • Collaboration between scientists and resource managers should be fostered so that research targets include development of information useful in resource management.

To see a complete list of the Coastal Conservancy’s natural infrastructure projects, click here.

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