Most beachgoers don’t think anything of the brown line of seaweed and other organic material that marks beach tide lines. This natural material that washes onto the beach – called wrack – includes algae, sea grasses and some invertebrates such as sponges and soft corals. Despite its unassumingness, wrack may be essential to helping dunes in protecting coastal shorelines from damaging weather such as hurricanes and tropical storms.
Researchers at the U.S. Army Engineer Research and Development Center (ERDC), along with partners at the U.S. Army Corps of Engineers (USACE) Mobile District and The University of Southern Mississippi (USM), are studying beach wrack to see if it is key to a more resilient dune system.
USACE Regional Sediment Management researchers are currently studying the placement of wrack that has washed up on beach coastlines, collected and then strategically placed on existing dunes to measure the stability of the dunes and how resilient they are to turbulent weather.
Dunes are standard features along sandy coastlines around the world, except for the Arctic and Antarctic that lack extensive coastal dunes.
A line of dunes can protect from flooding due to high water levels and wave overtopping. Dunes can also reduce wave damage in developed landward areas by causing waves to break as they propagate over the dunes.
“Many coastal communities rake their beaches because they view wrack as smelly and unsightly,” Leigh Provost, an ERDC research coastal engineer with ERDC Environmental Laboratory, said. “However, wrack material placed on the dunes can trap sand and assist with initiating natural dune-building processes, and through this method of wrack management, which is known as wrack-cycling, coastal communities are actually building protection for themselves while dealing with what they see as an economic problem.”
Unlike previous methods to construct man-made dunes, where dunes are built to an elevation and then planted with vegetation, researchers are evaluating how a man-made dune responds when biological material is incorporated into the dune incrementally, mimicking the natural growth cycle of dunes.
By making these dunes more resilient, USACE is also helping to reduce the need for future dune restoration construction projects and possibly even reducing the need for future beach nourishment.
For this ongoing study on the Mississippi Coast, Provost and her USACE and USM collaborators collect wrack and place it to test the effect on the resilience and stability of the dunes.
Placing the wrack by hand is time-consuming, but it has produced positive results despite large weather events that have pounded the coastline.
“We recently came under the Engineering With Nature® (EWN) program at the beginning of FY23, and I am very excited to continue to test in the Mobile District, which is an EWN Proving Ground,” Provost said. “The Mobile District and the Harrison County Sand Beach Authority have been very open to trying new theories to research, and it will be interesting to see where this allows us to take our research.”
After Tropical Storm Cristobal, Hurricane Zeta and other hurricanes, the team was able to observe that the dunes in the study area lost volume but had a noted visible benefit of wrack placement along the treated dunes shared Eve Eisemann, previously a research physical scientist with ERDC’s Coastal and Hydraulics Laboratory.
Continuing to assist the program under the EWN umbrella, USM’s Gulf Coast Geospatial Center provides high-quality surveys of the area using the most precise equipment available, leveraging state-of-the-art survey-grade equipment and a team of experienced staff, faculty and students.
The different instrumentation used for the precise measurements includes a variety of land-based and aerial, drone-based lidar devices used over a multi-day survey.
That experience of both the geospatial science and knowledge of the Mississippi coastline has made USM’s Gulf Coast Geospatial Center a key partner in the research.
In the United States, approximately 127 million people live in coastal counties, according to the National Oceanic and Atmospheric Administration. That’s as much as the entire population of Japan.
“With so many people living along the coastlines, the impact of a storm can be billions of dollars,” Provost said. “That’s why research such as wrackcycling is so important to USACE and the United States. It’s imperative that we find solutions quickly to protect these communities.”
According to the Environmental Protection Agency, United States has lost more than half of its wetlands since the 1600s, and approximately 35 percent of the world’s wetlands were lost between 1970 and 2015. To protect against further impairment of wetlands and the essential functions they provide, the U.S. established a policy of "no net loss" of wetlands, as well as procedures to ensure responsible management of wetland resources.
As a result, the U.S. Army Corps of Engineers (USACE) requires the completion of a wetland delineation for essentially all construction activities that occur in the nation’s wetlands to establish the location and extent of those wetlands to comply with federal, state and local regulations. There are approximately 74,000 USACE regulatory actions each year related to wetland and aquatic resource permitting.
To simplify and expedite this process for the public, scientists with the U.S. Army Engineer Research and Development Center (ERDC) collaborated with regulatory staff of the USACE Detroit District (LRE) to develop Automated Wetland Determination Data Sheets (ADS), which were released for public use in April 2022.
“The ADS are a practical, readily applied technology that streamlines and improves the accuracy of the permitting process by automatically calculating many of the field indicators of wetland vegetation, hydrology and soils based upon user inputs,” said Dr. Jacob Berkowitz, a research soil scientist with ERDC’s Environmental Laboratory. “We’ve received very positive feedback from the private sector and agency staff who are now using the ADS to conduct wetland delineations across the nation.”
ADS were developed through a collaborative effort between Berkowitz and LRE Biologist Nathan Schulz.
“Nathan developed much of the framework and code underlying the ADS, while ERDC did a lot of the early technical work on the data sheets,” Berkowitz said. “Once the template was set, Nathan did most of the execution, and ERDC did a lot of the beta testing to ensure technical accuracy and to demonstrate the value of the ADS.
“The collaboration between ERDC and LRE, coupled with public engagement and technology transfer, highlights the capacity of the agency to develop and transition practical, impactful tools for the nation.”
Schulz said the collaboration between ERDC and LRE moved ADS from a local project to one that will benefit the entire country.
“I had originally developed the ADS just for my district and only for one of the Regional Supplements, the North Central and Northeast,” Schulz said. “I had met with Jacob and shown him what I had done, and that began our project to expand it out to the entire country. His knowledge of the Regional Supplements is vast, so I was constantly bombarding him with questions. We both had some great ideas to make the ADS more functional.”
Wetlands are a highly productive, biodiverse natural resource that occur where terrestrial and aquatic ecosystems meet. They provide an array of ecological functions that benefit society, such as reducing flood and storm surge damage, supporting fisheries and wildlife, improving water quality, reducing sedimentation, enhancing recreational opportunities, and providing economic and cultural value.
Since the 1980s, USACE scientists have conducted fundamental research in wetland ecology and developed tools and approaches to identify where wetlands occur on the landscape. In collaboration with other organizations, this work helps protect, enhance and restore wetland resources across the nation.
The USACE Regulatory Program is committed to protecting aquatic resources and navigation capacity, while allowing reasonable development through fair and balanced decisions. USACE evaluates permit applications for essentially all construction activities that occur in the nation's waters, including wetlands.
Additionally, wetland delineations are required any time activities associated with USACE projects have the potential to negatively impact wetland resources. As a result, wetland delineations can influence USACE decisions across the enterprise, including planning, environmental, operations, navigation and real estate considerations.
In the past, wetland delineation data was documented using paper forms. Environmental consultants, public sector practitioners and agency staff would collect field data documenting the predominance of wetland vegetation, hydric (wetland) soils and signs of hydrology before conducting calculations and analysis prior to submitting permit applications to USACE. Then USACE staff would review the forms for technical accuracy and omissions, which often required requests for corrections or additional data and frequently slowed the permitting process.
The next steps for the ADS include adding additional functionality and links with geospatial tools to further improve accuracy and efficiency. The team is also working to transition ADS for use on mobile devices, a process that is being beta tested by USACE Regulatory staff in the field.
Automated Data Sheets and a User Guide are available at: https://www.usace.army.mil/Missions/Civil-Works/Regulatory-Program-and-Permits/reg_supp/ under the General Information tab.