Case Studies of Natural Shoreline Infrastructure in Coastal California
This report describes natural infrastructure projects implemented in coastal California to support adaptive planning and solutions regarding climate-related coastal hazards. Five case studies of successful adaptation projects to address coastal issues are provided, demonstrating different strategies for varying coastal environments. The report makes the case that natural shoreline infrastructure is a better alternative to engineered structures such as seawalls that increase erosion. Natural infrastructure is more likely to preserve the benefits of coastal ecosystems which provide flood protection, recreation, wildlife habitat, water quality and more.
Five projects that span the California coast and represent different coastal settings and corresponding approaches constitute the body of the report. Each case study covers the background, permitting, planning, implementation, performance, and key lessons learned from each project. Corresponding strategies employed for each project are listed below:
Seal Beach National Wildlife Refuge Thin-layer Salt Marsh Sediment Augmentation Pilot Project
Strategies: Beneficial use of dredge material; and Thin-layer sediment augmentation to marsh surface
Surfers’ Point Managed Shoreline Retreat Project
Strategies: Managed Retreat; Vegetated Dunes; Cobble Berm; Beach nourishment (sand and cobble); Bioswales for stormwater retention and filtration; and Permeable Parking Lot
San Francisco Bay Living Shorelines: Nearshore Linkages Project
Strategies: Eelgrass (Zostera marina) bed restoration; Olympia oyster (Ostrea lurida) reef restoration; Living Shorelines Approach
Hamilton Wetland Restoration Project
Strategies: Intertidal berms; Managed realignment/retreat; Beneficial use of dredged sediment; Levee breach after placing sediment to raise elevation; Wildlife corridor - gently sloping habitat levee; Seasonal wetland development; Site planting through adaptive management; Permits, Leases, and Authorizations; National Marine Fisheries Service Biological opinion; US Fish and Wildlife Service Biological Opinion; San Francisco Regional Water Quality Control Board 401 Certification; BCDC Consistency Determination for USACE; BCDC State Permit for State Coastal Conservancy; and Lease of adjacent property from State Lands Commission
Humboldt Coastal Dune Vulnerability and Adaptation Climate Ready Project
- Test sea level rise adaptation in areas of positive to neutral sediment budget;
- Removal of invasive over-stabilizing vegetation;
- Planting several different configurations of native species with different morphologies and sand trapping abilities to test effectiveness in allowing sand to be transported to and over the crest of the primary foredune;
- Evaluate sediment budgets and morphodynamics in different vegetation treatments using Terrestrial LiDAR scanning and orthophotographs using a kite platform to evaluate the relative effectiveness of the different treatments and control (European beachgrass) in allowing translation to occur;
- Test foredune building as adaptation strategy in sediment starved areas;
- Quantify beach-dune sediment dynamics and identify vulnerabilities of the beach-dune system to sea level rise and extreme events along the littoral cell; and
- Model sea level rise scenarios.
Case Studies of Natural Shoreline Infrastructure in Coastal California is a component of Identification of Natural Infrastructure Options for Adapting to Sea Level Rise within California’s Fourth Climate Change Assessment.
Publication Date: November 27, 2017
- Best practice
- Case study