What can we learn from soil cores? Soils and sediment can tell us a lot about the health of a wetland, including nutrient concentrations, average productivity, and flooding patterns. There’s a rich history in every… More
Hydrologic Restoration and Vegetative Planting (BA-34-2)
Problems:
The Lac des Allemands River Basin Initiative identified the following specific problems within the Lac des Allemands Watershed: drainage impairments; water quality impairments; loss of marsh; and decline of cypress forest. Many years of study by Louisiana State University researchers in these swamps have demonstrated that, because of impoundment, subsidence, and inadequate accretion of sediments and organic matter, some areas are already highly stressed and converting to open water, floating aquatic plants, and fresh marsh. Also, the Coast 2050 report suggests that other areas of the swamps throughout the basin will likely convert to open water or floating marsh by the year 2050. These problems are caused by the loss of river water along with the associated sediment and nutrients necessary for swamp health. The loss of river water can be attributed to the leveeing of the Mississippi River. Impoundment caused by roads, drainage canals, and spoil banks is also a major cause of degradation of these swamps.
Restoration Strategy:
The original proposed restoration strategy included installing two small siphons (averaging 400 cubic feet per second) to divert water from the Mississippi River; gapping spoil banks on Bayou Chevreuil; gapping spoil banks along the borrow beside Louisiana Highway 20; installing culverts under Louisiana Highway 20; improving drainage in impounded swamps; and planting cypress and tupelo seedlings in highly degraded swamp areas.
The proposed diversion from the Mississippi River was to bring fresh water, fine-grained sediments, and nutrients into the upper des Allemands swamps, which would have helped maintain swamp elevation, improve swamp water quality, and increase productivity and regrowth of young trees as older trees die. However, after hydrologic modeling and more detailed engineering/design and cost estimation, it was determined that the siphon would cost far more than originally anticipated. For that reason, the CWPPRA Task Force approved the project sponsors’ request to re-scope the project to eliminate the siphon feature, and to focus on the remaining project features.
Location: The project is located West of Lac des Allemands in St. James Parish, Louisiana, south of the town of South Vacherie, bordered on the south by Bayou Chevreuil, and on the east by LA Highway 20.
Progress to Date: The Louisiana Coastal Wetlands Conservation and Restoration Task Force approved Phase 1 funding in January 2001. In June 2013, the Task Force approved a request to change the scope of the project to eliminate a siphon feature and focus on the remaining original hydrologic restoration and vegetative planting project features. The Louisiana Coastal Protection and Restoration Authority performed the engineering and design services. Design was completed in October 2015 and Phase 2 funds for construction was approved by the Task Force in January 2016. Construction activities for excavation and placement began in October 2017 and ended on December 20, 2017, vegetative plantings occurred in late January, and officially completed on February 2, 2018.
The three (3) principal project features included:
1. Eight (8), 400-foot-long, strategically designed gaps were cut in the northern Bayou Chevreuil spoil bank to reverse the effects of impoundment;
2. Sixteen (16) spoil placement areas were created on each side of the channel banks; (1 placement area on both sides of each gap) to beneficially use the dredged material on site;
3. Seven hundred (700) Bald Cypress and one hundred (100) Water Tupelo saplings were planted in the constructed spoil placement areas to start swamp regeneration and swamp productivity.
This project enhanced 2,395 acres of swamp habitat that would have continued to degrade without the project.
This project is on Priority Project List (PPL) 10.
The sponsors include:
Federal Sponsor: U.S. Environmental Protection Agency
Local Sponsor: Coastal Protection and Restoration Authority (CPRA)
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]
Classifying Wetlands Part 1
When we think of wetlands, our mind may paint a picture of a swampy area with open water, and maybe a heron or alligator. Despite common perception, not all wetlands are the same. — These watery features come in all shapes, sizes, and locations along with a unique system of processes and purpose.
Wetlands are diverse and the difference between dry and wet environment lies along a gradient. Therfore, there cannot be one perfect definition to represent what a wetland is. Scientists have developed criteria to identify wetlands and aid in assessment, inventory, and management [1].
Figure 1. An example used by scientists to start the process for wetland delineation.
| Criteria | Definition |
| Wetland hydrology | the gradient or degree of flooding or soil saturation across a landscape [2]. |
| Hydrophytic vegetation | plants adapted to grow in water or in a soil that is occasionally oxygen deficient due to saturation by water [2]. |
| Hydric soils | soils that are sufficiently wet in the upper root zone and may develop anaerobic (oxygen lacking) conditions during the length of at least 1-2 growing seasons [2]. |
As seen below in Figure 2 and 3; some wetlands are flooded year-round while other water levels fluctuate. The wetland hydrology differs depending on location and the geography of the landscape.
Figure 2: A simplified example of a wetland water gradient dependent on elevation and tidal ranges.
Figure 3.
You may not live close to a coastal marsh, but many water sources eventually connect to a wetland on the coast, making the streams, lakes, and swamps in your backyard an important link to the larger watershed. That’s why it’s important to support, respect, and appreciate the water systems and land of everyday life. CWPPRA projects restore and protect these systems to support the livelihood and cultures of Louisiana and to protect the land we value so dearly.
In next week’s edition of Wetland Wednesday, we’ll look at how scientist use vegetation and soils to classify wetlands!
Source:
[1] Fish and Wildlife Service. Classification of Wetlands and Deepwater Habitats of the United States. Available: https://www.fws.gov/wetlands/documents/Classification-of-Wetlands-and-Deepwater-Habitats-of-the-United-States-2013.pdf [August 27, 2018].
[2] Natural Resources Conservation Service. Hydric Soils Overview. Available: https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/use/hydric/?cid=nrcs142p2_053985 [August 27, 2018].
Hurricanes
This week marks 13 years since Hurricane Katrina, an event some citizens of Louisiana are still recovering from. We may have all heard the name, but do we know what a hurricane is, how wetlands are affected, and how coastal landforms can decrease hurricane impacts?
“Hurricanes” are low-pressure tropical storm systems that differ from other storms in severity as well as location. A hurricane is a storm with winds above 64mph accompanied by heavy rain that originates in either the NE Pacific or the N Atlantic Ocean (the oceans that touch the USA). Due to a phenomenon called the Coriolis Effect, hurricanes rotate counter-clockwise, whereas a southern hemisphere storm would rotate clockwise. Hurricanes develop a characteristic “eye of the storm” in the center, which is an area of low pressure and low wind. Just outside of the eye is the most severe weather, the eyewall, with winds reaching up to 210mph in the strongest storms! Hurricane “category” ratings are as follows:
- Category 1: 74-93mph
- Category 2: 96-109mph
- Category 3: 110-129mph
- Category 4: 130-157mph
- Category 5: >158mph
Hurricanes develop over areas with warmer waters, typically nearer the equator, and move away from the equator. [1] Coastal Louisiana is hit by hurricanes on an increasingly regular basis, and those hurricanes all develop in the North Atlantic Ocean in late summer and fall. Our “Hurricane Season” occurs from June through November each year. [2] Several aspects of hurricanes pose major threats to our wetlands statewide. High winds can topple trees, rip up shrubs and grasses, and move sediments around. High rainfall can cause flooding in areas that are not well-adapted to high-water conditions. Storm surge can push saline seawater into brackish and freshwater systems. Hurricanes cause massive disturbance in coastal wetlands, but wetlands are a crucial barrier that protects major cities from taking as much damage. CWPPRA works to combat land loss and protect the future of coastal Louisiana.
Some CWPPRA projects restore barrier islands, which are natural defenses that develop in the Deltaic Cycle. Barrier islands lessen storm surge during hurricanes, bearing the brunt of the waves. Sadly, they cannot provide perfect protection because they are degrading, but they are not the last line of defense. We still have coastal marshes that are great at storing water and acting like a speed bump to storm surge. It is estimated that each mile of coastal marsh decreases storm surge by about a foot. Unfortunately, many coastal marshes are decaying into open water and are no longer protective barriers. CWPPRA will continue to restore wetlands and nourish barrier islands to #ProtectOurCoast!
[1] https://en.wikipedia.org/wiki/Tropical_cyclone
[2] https://www.ready.gov/hurricanes
Featured image from [1]
Raccoon Island Shoreline Protection/ Marsh Creation (TE-48)
The Isles Dernieres barrier island chain is experiencing some of the highest erosion rates of any coastal region in the world. Raccoon Island is experiencing shoreline retreat both gulfward and bayward, threatening one of the most productive wading bird nesting areas and shorebird habitats along the gulf coast.
An existing demonstration project on the eastern end of the island, Raccoon Island Breakwaters Demonstration project (TE-29), has proven that segmented breakwaters can significantly reduce, and perhaps even reverse, shoreline erosion rates. The primary goal of this project is to protect the Raccoon Island rookery and seabird colonies from the encroaching shoreline by: 1) reducing the rate of shoreline erosion along the western, gulfward side and 2) extending the longevity of northern backbay areas by creating 60 acres of intertidal wetlands that will serve as bird habitat. This project has been separated into two construction phases, Phase A and Phase B. Phase A includes the construction of eight additional segmented breakwaters gulfward of the island and immediately west of the existing breakwaters demonstration project and an eastern groin that will connect existing Breakwater No. 0 to the island. Phase B involves the construction of a retention dike along the northern shore to create a back bay enclosure that will be filled with sediments dredged from the bay and/or gulf, followed by vegetative plantings.
The project is located in the Terrebonne Basin on the western-most island of the Isles Dernieres barrier island chain in Terrebonne Parish, Louisiana.
This project was selected for engineering and design funding at the January 2002 Breaux Act Task Force meeting. Construction funding for Phase A was approved in October 2004. Request for Phase B construction funding is anticipated to occur in January 2008.
This project is on Priority Project List 11.
The Sponsors include:
Federal Sponsor: NRCS
Local Sponsor: CPRA
Seasonal Change in Wetlands
In honor of the official “First Day of Fall” on Saturday, September 22, let’s fall into seasonal changes in wetlands! When many people think of the transition from summer to autumn, the first thing that pops into their heads is leaves changing colors and seeing more sweaters and long pants. A less common thought is how wetlands change in the later months of the year. From species composition to hydrology, many wetlands undergo radical changes when summer turns into fall. Wetlands in coastal Louisiana are no exception.
For a start, seasonal changes can be observed with migratory species. Many species of birds and some fish and crustaceans use our swamps, estuaries, and other wetlands for breeding habitat in the summer months because of the abundance of food and warmth. On the other hand, some migratory birds like the famous Bald Eagle use the Mississippi River Delta as a wintering ground. [1] Blue Crabs, another species found in wetlands, mate around this time of year before going dormant for the winter. [2] Migratory birds are starting to migrate back to the southern hemisphere around this time to follow food resources.
Decreasing temperatures and humidity also cause plant communities to change. Wetlands experience loss of vegetation from wilting and freezes. [3] Black Mangrove distribution is limited by minimum winter temperatures. You can read more on mangroves and freezing here. Swamps and marshes lose much of their greenery with lower temperatures, which really decreases their water storage potential. Evapotranspiration, or water vapor leaving plants through their leaves, often decreases too, which means that water is not being cycled as quickly as at other times of the year.
Ecosystems in a stable state can weather the changes between seasons and bounce right back to full productivity in their peak season, but sometimes a large disturbance or even small, incremental changes over time can degrade habitat to the point of no return. Degraded wetlands provide less storm buffer, which is a crucial ecosystem service that protects us during hurricanes. It is in our best interests to preserve our wetlands through projects like CWPPRA because they are so critical and invaluable to us.
[2] https://www.bluecrab.info/mating.html
[3]http://www.loyno.edu/lucec/natural-history-writings/winter-swamp
Featured Image from https://www.hcn.org/articles/the-disappearing-wetlands-in-californias-central-valley
National Estuary Week
In honor of National Estuaries Week, we have information on how to care about the health of estuaries near you!
Twenty-two of the thirty-two largest cities in the world are located near estuaries, and with good reason. The ecosystem benefits of estuaries are massive, including major shipping channels, fisheries, agriculture, and tourism.[1] The high productivity in these areas means that they are hugely beneficial to societies near them. In coastal Louisiana, many jobs and industries are directly dependent on a healthy estuarine system.
We in Louisiana are lucky to host one of the 28 National Estuary Programs supported by the United States Environmental Protection Agency (EPA). Each National Estuary Program focuses on a different estuary, each one distinct and complicated, but they all share concerns about water quality and ecological integrity. Together the programs have restored or protected over 2 million acres across the nation since 2000. Our local NEP, the Barataria-Terrebonne National Estuary Program (BTNEP), seeks to maintain the breeding habitat of shrimp, blue crabs, and many fish species that have come to be a huge industry in the state. Other estuaries host different fisheries and different industries, for example the Puget Sound Partnership Comprehensive Plan includes support for salmon fisheries, resident orca populations, and goals for reducing shore armoring. BTNEP is based out of Nicholls State University in Thibodaux, LA, and they have a bounty of information on their website about their work, worries, and successes in maintaining one of the most productive ecosystems on the gulf coast. Anyone interested in protecting and restoring the estuary is welcome to participate in the BTNEP Management Conference which meets three times a year. People can also take part in beach clean ups, water quality monitoring, and local events to highlight recreational opportunities in the Barataria-Terrebonne area.
Many other programs and organizations are dedicated to the preservation of our estuaries, including RESTORE the Mississippi River Delta, America’s Wetland Foundation and CWPPRA’s Partners in Restoration. All of these programs understand the issues that threaten coastal Louisiana and the people who call it home.
[1]https://oceanservice.noaa.gov/education/kits/estuaries/estuaries03_ecosystem.html
Featured image from http://mississippiriverdelta.org/diversions-old-vegetation-and-new-vegetation/
Black Bayou Hydrologic Restoration (CS-27)
The purposes of the Black Bayou Hydrologic Restoration
project are to (1) restore coastal marsh habitat, and (2) slow
the conversion of wetlands to shallow, open water in the
project area. The project limits the amount of saltwater
intrusion into the surrounding marsh and canals from the
GIWW and reduces erosion caused by wave action from
nearby boats and tides.
A 22,600-foot rock dike was placed on the southern spoil
bank of the GIWW. A barge bay weir (70-foot bottom
width) was constructed in Black Bayou Cutoff Canal. Weirs
with boat bays (10-foot bottom widths) were constructed in
Burton Canal and Block’s Creek. A collapsed weir was
plugged and replaced by a fixed crest steel sheet-pile weir
with a state-of-the-art, self-regulating tidegate. Spoil
material from weir installation and the dredging of access
routes was deposited in nearby open water areas to the
height of marsh elevations. The $3 million construction
contract included installation of 55,000 marsh plants over the
next two planting seasons.
This project, sponsored by the National Marine Fisheries
Service and the Louisiana Department of Natural Resources,
is a 25,529 acre wetland located in Cameron and Calcasieu
Parishes, Louisiana. Bordered by the Gulf Intracoastal
Waterway (GIWW), Sabine Lake, Black Bayou, and Gum
Cove Ridge, the project area consists of tidally-influenced
intermediate and brackish marshes.
Construction is completed. Installation of vegetative
plantings were completed in April 2002. The monitoring
plan was finalized in March 2000, and monitoring has
begun.
This project is on Priority Project List 6.
Federal Sponsor: NOAA
Local Sponsor: CPRA
