Evolving Study of Wetlands

From towing an airboat to a site, to driving the vessel, to taking samples in the hot, humid sun, there are many challenges for researchers as they study coastal wetlands.  Thanks to innovations in drone technology, researchers can study the wetlands a little easier. With free movement in every direction, a camera, and various other attachments, drones can gather enormous amounts of data in a fraction of the time that it would take more traditional methods. Drones are far from alone on the forefront of technological advancement. Innovations in drones sit alongside and often work synergistically with GIS/GPS, remote sensing, and machine learning breakthroughs, to name a few.

In addition to the evolution of drone technology, computer software and hardware systems evolve just as quickly, consistently streamlining data collection, processing, and analysis. The two go hand-in-hand, of course; complex software can only be run with more powerful or specialized computer hardware, tailored to the task it will be performing. Major game-changers challenge the norms and traditions of science increasingly more often. In the past several decades, satellite imagery has become more prevalent, drones have allowed scientists and others to access new perspectives, and machine learning has grown to process more parameters at higher speeds. All of this advancement in computing has allowed scientists to develop greater understandings of systems, connectivity, and changes in wetlands.

In addition to improvements in drones, software, and processing power, researchers have improved the development of environmental models. Louisiana’s Coastal Protection and Restoration Authority, one of CWPPRA’s managing agencies, joined with LSU to design, manufacture, and implement the Center for River Studies’ scale model of the Mississippi River in 2017. An amazing feat of engineering, the river model allows scientists to study several aspects of our coastal zone. Using a sediment medium that mimics Mississippi River sediments, studies can predict what will happen during a flood event, if a diversion gets installed, and so many other situations. Hydrology, sedimentation, and potential ecological impacts can all be measured on this 10,000 square-foot platform at approximately a 13:1-time scale, i.e. one full day running the model represents about thirteen full days on the real Mississippi River.

In a dynamic landscape like coastal Louisiana, good equipment is a huge benefit to studies and planning for the future. Land loss is a complex issue with several moving parts that need to be studied and addressed. It is imperative that there is a good understanding of the full system before any changes are made that could have detrimental effects on any important aspects of our productive, populated, and protective coast.

 

Related articles:

https://www.sciencedirect.com/science/article/pii/S1364815217311295

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/remote-sensing

https://www.sciencedirect.com/science/article/pii/S0925857417303658

 

Featured image from https://blog.nature.org/science/2016/09/27/flight-over-the-bas-ogooue-using-drones-to-map-gabons-wetlands/

Classifying Wetlands Part 2

Last week’s Wetland Wednesday mentioned 3 main criteria as part of identifying a wetland (wetland hydrology, hydrophytic vegetation, and hydric soils). – Today we’ll look at how plants and soils help scientists delineate wetlands.

In the field, scientists identify and sample soils and plants as part of wetland delineation. The LSU AgCenter groups plant species based on where the plant is naturally found as seen in the table below.

Wetland plants have adapted to flooded soils. “Obligate” plants can tolerate water at high levels or when soil saturation is a normal condition to that area. Examples of these plants include the bald cypress (Taxodium distichum), or cattail (Typha latifolia) [3].

In contrast, plants that cannot handle flooded conditions for an extended period would naturally be in the “upland” area of land (i.e. winged sumac (Rhus copallina), eastern redbud (Cercis canadensis), or panic grass (Dichanthelium sp.) [3].

People delineating wetlands focus on a project area according to aerial and soil maps along with aerial photographs [1]. Delineators then take soil samples and determine characteristics seen in hydric soils which relate to cycles of flooding and drying. – Examples of those include oxidized soils, hydrogen sulfide (rotten egg smell) and organic bodies found on plant roots. Finally, the plant and soil types are compared, tested, then matched to determine wetland boundaries for mapping and policy purposes [1].

Wetland delineation is a tool for protecting and documenting these important landscapes which contribute to a healthy and functional environment. It is important to note that wetland delineation requires much more than just plant and soil identification. CWPPRA utilizes sound science, engineering, mapping, and geo-technical surveys in the process of planning, approving, constructing, and maintaining coastal Louisiana wetland restoration projects.

Sources:

[1] Bedhun, Rebecca. 2018. “Watch and Lean Now: How To Do A Wetland Delineation”. Shoret Elliot Hendrickson Inc. Available: http://www.sehinc.com/news/watch-and-learn-now-how-do-wetland-delineation [September 9, 2018]

[2] Jon Kusler. “Common Questions: Wetland Definition, Delineation, and Mapping”. Association of State Wetland Managers, Inc. Available: https://www.aswm.org/pdf_lib/14_mapping_6_26_06.pdf [September 9, 2018]

[3] LSU Ag Center. 2018. Louisiana Plant Identification: Plant List. Available: http://www.rnr.lsu.edu/plantid/listcommon.htm [September 10, 2018]

 

Measuring Elevation Change

To provide the best possible care, doctors first must know what is going on with their patients. The same goes for ecologists and engineers with wetlands. Just like doctors can measure your growth and deduce what could help you get over a sickness, ecologists measure the “health” of ecosystems to try to keep them healthy.

Wetland habitats have many moving parts which makes them difficult to fully understand, but we can get a pretty good idea of whether they are growing or deteriorating and sometimes why. All CWPPRA projects require significant amounts of research to estimate the benefit of the project and minimize any damage that could come from disturbing already established wetlands. CWPPRA funds the Coastwide Reference Monitoring System (CRMS) program, which provides reliable coastal elevation data to scientists. Completed projects are monitored for wetland health factors including land accretion, productivity, and water quality to determine whether they are making a positive impact on coastal systems.

Elevation studies are necessary across our coast since we experience such high levels of sediment subsidence. Elevation can be measured in a variety of ways, such as geodetic leveling, Interferometric Synthetic Aperture Radar (inSAR), or satellite imaging. [1] Because of the lower precision, satellite imaging is not great for measuring elevation change for a specific point but is relatively reliable for larger changes over longer periods of time. Another common technique for measuring elevation change in wetland ecology is Rod Surface Elevation Tables with Marker Horizons (RSET-MH), which is implemented at all CRMS sites.

 

RSET-MH diagram with deep benchmark, shallow benchmark, marker horizon [2]

An RSET is attached to a deep benchmark that will resist erosion and accretion, somewhere between 20 and 25 meters below the surface of the marsh, where the hard-packed sediments lie. With a benchmark, scientists can measure the relative surface elevation . To measure the rate of sediment accretion between two time periods researchers deposit a layer of white clay on the soil’s surface, called a marker horizon. At a later date, researchers return to the site, collect a core sample, and measure the amount of sediment above the white clay to calculate an accretion rate. [3] RSET-MH is great for measuring one specific site for small and precise elevation changes, but is limited in area coverage. Luckily, through the Coastwide Reference Monitoring System, we are able to monitor elevation change and accretion rates at over 390 sites across the coast!

Measuring wetland health has many factors, not only elevation change. Check in next week for our next installment on wetland monitoring!

 

[1] https://www.epa.gov/wetlands/wetlands-monitoring-and-assessment

[2] https://www.researchgate.net/figure/Rod-surface-elevation-table-marker-horizon-RSET-MH-in-both-shallow-and-deep_fig2_281113921

[3] https://www.pwrc.usgs.gov/set/

Featured Image from https://oceanservice.noaa.gov/sentinelsites/chesapeake-bay/welcome.html

The CWPPRA Public Outreach Committee

The Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) is federal legislation enacted in 1990 to identify, prepare, and fund construction of coastal wetland restoration projects in Louisiana. As part of the CWPPRA program, there is also the CWPPRA public outreach committee.

The CWPPRA outreach committee works with people of different ages, backgrounds, and interests from across the state and country. The committee works to develop an appreciation for the unique wetlands of Louisiana, and the role that CWPPRA has in protecting and restoring those resources. Although based in Lafayette, Louisiana at the USGS Wetland and Aquatic Research, outreach staff travel across Louisiana and beyond to talk with policy-makers, educators, fishermen and hunters, scientists, and community members.

Outreach at Audubon Aquarium of the Americas

Terrebonne Parish Coastal Day

Since a diverse group of stakeholders have an interest in protecting Louisiana’s coast, the outreach staff network with many groups and participate in a variety of activities including:

• hosting a yearly Dedication Ceremony for recently completed projects;
• developing educational materials like Henri Heron’s Activity Book and WaterMarks magazine;
• exhibiting at national conferences like State of the Coast 2018 and Restore America’s Estuaries Summit 2016;
• working with CWPPRA Task Force, Technical Committee, and Working Group members to communicate the importance of our projects to the public at local events like Terrebonne Parish Coastal Day;
• maintaining the LUCC calendar for coastal events.

The CWPPRA Public Outreach Committee enjoys talking to people about our interest in coastal Louisiana, and these conversations aid in the progress of coastal wetland restoration. Given the complex nature and scale of land loss in Louisiana, it takes many people working together to help restore the coast. — CWPPRA Outreach educates the public about why coastal wetland restoration is important and how CWPPRA projects contribute to supporting these habitats and communities.

More information about the outreach materials available can be found at lacoast.gov.

Bayou Teche Black Bear Festival

Working with teachers at WETSHOP

West Belle Pass Barrier Headland Restoration (TE-52)

This headland experiences some of the highest shoreline retreat rates in the nation, measuring over 100 feet a year in some locations. As the gulf encroaches upon the shoreline, sand is removed and the headland erodes. What was once a continuous shoreline spanning several miles has been reduced to less than half its original length. Furthermore, Hurricanes Katrina and Rita removed most of the emergent headland and dunes west of the pass. This headland helps provide protection to interior marshes and the Port Fourchon area; however, its continued degradation threatens the fragile bay habitat and infrastructure it once protected.

This project will reestablish the West Belle headland by rebuilding a large portion of the beach, dune, and back barrier marsh that once existed. Approximately 9,800 feet of beach and dune will be rebuilt using nearly 2.8 million cubic yards of dredged sand, and 150 acres of marsh habitat will be rebuilt using nearly 1.4 million cubic yards of dredged material. Native vegetation will be planted upon construction to help stabilize the rebuilt marsh and dune habitat.

The project is located along the Chenier Caminada headland to the west of West Belle Pass, at the southeastern edge of Timbalier Bay in Lafourche Parish, Lousiana.

This project was approved for engineering and design in October 2006. Construction funds were approved by the Task Force in late 2009, construction began fall 2011, and construction was completed in October 2012.

This project is on Priority Project List 16.

Federal Sponsor: NOAA NMFS

Local Sponsor: CPRA