HUMBOLDT COASTAL RESILIENCE PROJECT
We are excited to announce that the Humboldt Coastal Resilience Project (formally Dunes Climate Ready Project) has been continued for an additional 3 years through grants from the Ocean Protection Council and the California State Coastal Conservancy. This Quarterly Update covers the beginning of year 4 in this 6-year study which will improve understanding of sediment movement along the entire Eureka littoral cell, a 32-mile stretch of coastline composed of barrier dune systems. The study will identify potential vulnerabilities to climate change in order to develop decision support tools and adaptation measures for future sea-level rise and extreme weather events. More information on Phase I of the project can be found here.
A combined total of $430,750 was awarded to the Friends of the Dunes, who are the fiscal receiver and will oversee the outreach component of the grant. Funding will cover the following tasks: 1) Continuation of littoral cell cross-shore transects for an additional 2 years, resulting in a total of 5 years of data, 2) Continuation of monitoring of the Lanphere and Eel River adaptation sites, 3) Implementation of a second replication of the Lanphere adaptation site methodology in a new location, 4) Revise and update the Eureka littoral cell fluvial sediment budget, 5) Complete a vulnerability assessment for the study site, 6) Model responses of the beach-dune barrier complexes to sea level rise and extreme event scenarios, 7) Convene a stakeholder involvement group, and 8) Continue outreach activities.
Hilgendorf, Z., Walker, I.J., Pickart, A.J. & Turner, C.M. (2022) Dynamic restoration and the impact of
native versus invasive vegetation on coastal foredune morphodynamics, Lanphere Dunes, California,
USA. Earth Surface Processes and Landforms, 1–17.
2020 Project Updates
The winter 2020 survey was recently completed. Three teams were deployed, consisting of a crew leader who took topographic points and a vegetation surveyor who took vegetation measurements. Major changes had occurred at the transect near the mouth of the Mad River, which has been migrating north. One complete transect was underwater. The other major changes occurred at the south end of the littoral cell. This area has been actively eroding over the past several surveys. This year a large area near Centerville beach has become flooded.
Lanphere Adaptation Site
The adaptation site was monitored in September by Arizona State University, using terrestrial LiDAR scanning. Scans reveal that restoration has allowed the transport of sediments from the foredune stoss face to the lee of the foredune. A ramp has formed in the formerly scarped foredune stoss in all areas except the Ammophila control. This should allow for sediment transport from the beach to the foredune this summer.
Bair Adaptation Site
A second adaptation site was added in summer 2019 north of the Lanphere adaptation site. This site will differ from the Lanphere site in that no planting will be done following the removal of Ammophila arenaria. This will allow us to determine the role of planting in promoting resilience.
Eel River Adaptation Site
The Eel River adaptation site consists of a rebuilt foredune at the Eel River Estuary Preserve in an area where a foredune breach and washover site had occurred. Despite major erosion in the southern portion of the littoral cell, the ER adaptation site did not undergo significant erosion this winter. Wildlands Conservancy staff obtained native plants to revegetate the foredune, however, flooding conditions have so far prevented planting.
A vulnerability assessment for the Eureka littoral cell is nearing completion. Arizona State University has completed a first draft but are awaiting some outstanding data. The VA examines vulnerability in three broad categories: infrastructure, cultural resources, and natural resources. The VA will be made available to the public upon completion.
Figure 1. Cumulative changes on the foredune at the Lanphere adaptation site. Red is erosion and blue is deposition. This graphic illustrates deposition occurring on the lee (sheltered from the wind) side of the foredune.
2019 Project Updates
Littoral Cell Shoreline Monitoring
The winter 2019 survey was carried out in January and February. Extensive scarping (erosion resulting in a steep drop-off) was observed all along the littoral cell from a high water storm event in January. A summary of results to date will be distributed to collaborators and landowners after the summer survey.
Lanphere Adaptation Site
Arizona State University student Zach Hilgendorf, under the direction of Dr. Ian Walker, has completed data processing for the adaptation site terrestrial LiDAR scans from May 2017 through October 2018. Previous scans were processed by former graduate student Alana Rader. Zach is currently revising earlier data to make it compatible with the new scans so that change analysis can be completed from the start of the project through October 2018. Change maps from May 2017 to October 2018 are shown in Figure 1. Table 1 shows net change by time interval and foredune position for this same period. During this period, the study site overall showed net deposition during all intervals.
Photo points showing pre-treatment (summer 2015) and June 2018 are included below as Figures 2 & 3.
Figure 1. Erosion (red) and deposition (blue) in the Lanphere Adaptation Site from May 2017 through October 2018 (Zach Hilgendof).
Table 1. Significant changes in foredune volume in the Lanphere Adaptation site from May 2017 through October 2018 (Zach Hilgendorf).
Figure 2. Photopoint at foredune crest in Elymus treatment at Lanphere Adaptation Site showing changes from pre-treatment in summer 2015 through summer 2018. Planting occurred in December 2016.
Figure 3. Photopoint at foredune crest in dune mat treatment at Lanphere Adaptation Site showing changes from pre-treatment in summer 2015 through summer 2018. Planting occurred in January 2017.
Eel River Adaptation Site
The California State Coastal Conservancy funded an augmentation of the Climate Ready grant in 2018 to rebuild the foredune at a breach site on the Eel River Estuary Preserve with a goal of improving resilience to storm events. The new foredune was completed in 2018 and Arizona State University used a drone platform to create a Digital Elevation Model and imagery of the site. The foredune was not scarped during the winter 2019 high water event. Topographic profiles showing the site pre-project and in winter 2019 are shown in Figure 4, and a photograph of the foredune is shown in Figure 5.
Figure 4. Eel River Adaptation site showing construction of foredune.
Figure 5. View of the reconstructed foredune at the Eel River adaptation site.
DUNES CLIMATE READY GRANT PARTNERS
Us Fish and Wildlife Service, Friends of the Dunes, State Parks, Bureau of Land Management, The Wildlands Conservancy, The University of Victoria’s Coastal Erosion and Dune Dynamics Lab, California Department of Fish and Wildlife, Humboldt Bay Municipal Water District, Flinders University, Arizona State University and the consulting firm GHD.
CLIMATE CHANGE GLOSSARY
The first rise above the beach, and characterized by the native grass Elymus mollis ssp. mollis, which is able to tolerate the intense salt spray and sand deposition that occurs in this habitat.
The degree to which a system is susceptible to, or unable to cope with, adverse effects of climate change.
A natural compartment of the coast that contains a complete cycle of sedimentation.
An adjustment of a natural or human system to a new or change environment that moderates harm or exploits beneficial opportunities.
A capacity to anticipate, prepare for, respond and to recover from climate-change related threats.
An abnormal rise in sea level accompanying an intense storm or hurricane.