A Bird's Eye View on Bay Area Marshes (via Unoccupied Aerial Systems) Yields New Insights

SFEI continues to leverage our Unoccupied Aerial Systems (UAS) capabilities to support conservation and monitoring efforts around the Bay. Two recent projects include monitoring for the Sears Point Restoration Project in San Pablo Bay, as well as conducting a number of flights to support the US Environmental Protection Agency (USEPA) filming of existing marshes and marsh restoration projects that help protect both communities and critical infrastructure.

Sears Point UAS Monitoring

The Sonoma Land Trust restored the 940-acre Sears Point Tidal Marsh Restoration Project to tidal action on October 25, 2015 and the project is now part of the San Pablo Bay National Wildlife Refuge managed by the U.S. Fish and Wildlife Service. The constructed design for this subsided diked bayland allows natural sedimentation to raise site elevations relatively rapidly from around low tide heights at breach up to intertidal emergent marsh elevations, drawing upon the known high sediment loads of northern San Pablo Bay. The design also included a setback flood protection “habitat” levee with gentle slopes (10:1 to 20:1) and around 500 “marsh mounds” within the site interior. Wind-wave energy in the few years after breaching, when site elevations were low, and the absence of significant vegetation stabilization of the lower habitat levee and marsh mounds, resulted in extensive erosion. Levee erosion resulted in ongoing disturbance of establishing marsh and loss of the habitat levee slopes, impeding achievement of project objectives, but did not threaten the integrity of the flood protection levee.

In Fall 2021, Sonoma Land Trust implemented a “nature-based” shoreline adaptive management project with the goals of halting shoreline erosion, partially restoring habitat levee slopes, and setting the project back on its course to establishing emergent tidal marsh and the wetland-upland ecotone. The project used earth moving to regrade erosion scarps, placement of natural materials (reused dredged bay mud, reused flood control channel dredged gravel, reused large cut logs from power line and fire vegetation removals, and transplanted native vegetation sourced on-site), and the power of natural processes to achieve its goals.

A key component of project monitoring – baseline, as-built, and post-construction – is the collection of UAV imagery combined with ground control points to generate high resolution orthomosaic imagery and photogrammetric digital terrain model. From these data the monitoring tracks changes from the construction and the natural processes following construction, tracking habitat levee slope topography, nearshore marsh accretion, vegetation establishment, and movement and stability of constructed project elements. SFEI’s Pete Kauhanen worked with the project design team (Stuart Siegel, Dan Gillenwater, Peter Baye, and Roger Leventhal) to utilize its equipment and expertise to collect the as-built UAV data in December 2021 and the late-summer conditions monitoring in August 2022. The Year 1 monitoring report utilizing these UAV data are expected to be available in early 2023.

Wildcat Marsh, San Pablo Creek mouth, and Doston Family Marsh

Furthermore SFEI continues to leverage its UAS capabilities to help convey greater understanding and the importance of the bayland resources we study and ultimately help to protect. In September 2022, SFEI coordinated with both USEPA and East Bay Regional Park District (EBRPD) to conduct a number of UAS flights at marshes along Richmond’s bay shore. The goal was to capture compelling visuals demonstrating how existing and restored marshes protect local communities and critical infrastructure at the bay’s edge. Through this collaboration SFEI was able to capture video and still imagery at Wildcat Marsh, San Pablo Creek mouth, and Doston Family Marsh. Wildcat Marsh not only provides important habitat for bayland wildlife and sequesters carbon, but also helps protect infrastructure that our Bay Area communities rely on, such as the West County Wastewater treatment plant. Similarly Dotson Family Marsh provides benefits for wildlife and recreation, as well as protecting railroad lines and the Parchester Village community.