The goal of building terraces is to achieve some of the same objectives as full marsh creation but over a larger area of open water, where marsh creation alone is not feasible. Terraces are long, earthen berms that are built by mechanically dredging material and piling and shaping the material to a desired height. Most terraces average around 3 feet tall, with shallow side slopes and a wide base. This size and shape optimize the amount of terrace that falls in the intertidal zone and will support wetland vegetation.
The objectives of constructing terraces are several and depend upon the location in which they are built. These include acting as a sediment trap to help build new land, reducing wave fetch and erosion on adjacent marsh shorelines, creating habitat for fish and waterfowl, and improving water quality to promote the growth of aquatic vegetation. Terracing projects constructed under CWPPRA have achieved each of these goals, with sediment trapping being most evident near the openings of sediment-laden bays or navigational waterways.
Terracing has become a widely used technique that is expanding across the Gulf Coast because of the success and cost-effectiveness demonstrated through CWPPRA and privately funded projects. Although these features may not look like natural marsh and often use geometric configurations, they are able to perform a lot of the functions of natural marsh in areas that have become vast open water. Developing this cost-effective technique for use in areas that have few other restoration options is a testament to CWPPRA’s ability to adapt to funding constraints and a quickly changing environment.
CWPPRA Restoration Technique: Freshwater and Sediment Diversions
The present location of the Mississippi River has been confined by levees constructed in response to the devastating flood of 1927. Although necessary for protecting life and property, the levees prevent the natural processes of delta building and sediment deposition that are vital for sustaining wetlands. Without this nourishment, the wetlands will eventually succumb to subsidence, storms, and anthropogenic impacts.
The CWPPRA program has been finding solutions to optimize river resources and help rebuild wetlands with minimal impact to other stakeholders. Controlled diversions route river water through strategic locations in the levees to feed starving marshes. Crevasses, or cuts, are constructed through levees to allow passive creation of smaller deltas. Siphons suction fresh river water and direct flow into wetlands suffering from saltwater intrusion. Water-control structures and channel maintenance help distribute river water diverted from large-scale structures constructed under other authorities.
The river presents the greatest opportunity for rebuilding land but also the greatest challenges, as competing needs are inevitable. The human and natural environments must be able to coexist because they are inextricably connected. Together with stakeholders, CWPPRA projects are helping to reverse land loss on an ecosystem scale and support the economy on which coastal Louisiana has come to depend.
Barrier islands are known as coastal Louisiana’s first line of defense against destructive storm surge. These islands are a unique composite of beach, dune, marsh, and sand flats that host a tremendous variety of fisheries and wildlife, including endangered species. Barrier island restoration projects are designed to protect and restore the features unique to Louisiana’s barrier island chains. This type of project may incorporate a variety of restoration techniques, such as the placement of dredged material to increase island height and width, the placement of structures to protect the island from erosive forces, and the placement of sand-trapping fences, used in conjunction with vegetative plantings, to build and stabilize sand dunes.
Responsible for the majority of Louisiana barrier island restorations to date, CWPPRA has led the charge in barrier island restoration because it recognizes the ecological importance of barrier islands and their critical role in the defense of coastal Louisiana.
Water, promoter of all life forms on Earth, is recognized today- World Water Day! In Louisiana, 47% of the state’s population resides in the coastal zone, with a majority of livelihoods reliant on water. Industries such as aquaculture, agriculture, oil and gas, and tourism depend on the sustainability and quality of Louisiana’s waters. This essential natural resource has a synergistic relationship with Louisiana’s wetlands, providing vital nourishment to fisheries, wildlife, and Louisiana’s coastal growth. Wetlands improve water quality by trapping suspended solids and filtering other pollutants. Coastal marshes filter excess nitrogen and phosphorus, thus helping to prevent algal blooms and maintaining oxygen in the water for fish and shellfish. Wetlands can retain, remove, and transform nutrients that might otherwise contribute to declining water quality. Clean water is important for healthy fish, wildlife, and humans. Water is not only a commodity, but a contributor to life… appreciate it, preserve it, and protect it!
Water is the key to life, celebrate World Water Day!
Louisiana’s shorelines are eroding at a drastic pace, some at rates up to 50 feet per year. The fertile but fragile soils found in the wetlands are susceptible to wave energy. As land is lost, water bodies merge together, which can increase wave fetch and shoreline erosion. Behind these shorelines lie communities, highways, and infrastructure that are at risk of washing away.
Various techniques to defend the coastline have been tested and applied under CWPPRA. Rock revetments, oyster reefs, concrete panels, and other fabricated materials have been constructed along otherwise unstable shorelines to abate wave energy and reduce erosion. These structures are designed to break waves, and they often trap waterborne sediments behind the structures that, over time, can become new land.
Through the course of the CWPPRA program, advancements have been made in shoreline structures that have helped maintain natural processes while providing critical protection. Such advancements have included using lighter-weight materials that require less maintenance and can be constructed on organic sediments. Other advancements include low-relief structures that are designed to trap sediments and natural breakwaters such as reefs that can self-maintain and support other ecological functions. Other natural shoreline protection measures include vegetative plantings, whose roots help secure soils and can promote accretion. These projects are implemented with consideration for minimizing impacts to the surrounding environment. Although some shoreline structures may look foreign in a natural landscape, they are necessary features that physically protect communities and hold wetlands in place by mitigating the harsh forces that move to destroy them.
Plants are a vital piece of healthy and sustainable wetland ecosystems. Plants are the base of the food chain and can build new layers of organic material on top of wetlands which helps them keep pace with subsidence and rising waters. Wetland vegetation reduces erosion primarily by dampening and absorbing wave and current energy and by binding and stabilizing the soil with roots. Coastal wetland plant species are indicators of soil and hydrologic conditions. The amount and salinity of water in an area influence which plants grow there. Scientists often classify Louisiana marshes into four types: fresh, intermediate, brackish, and saline.
The Coastal Wetlands Planning, Protection, and Restoration Act puts native wetland plant benefits to use through restoration techniques that include vegetative plantings. Vegetative planting projects are used both alone and in conjunction with barrier island restoration, marsh creation, shoreline protection, and sediment and nutrient trapping restoration techniques. These projects use flood-and salt-tolerant native marsh plants that will hold sediments together and stabilize the soil with their roots as they become established in a new area.
Environmental Studies students in Christina Hidalgo’s class at the Episcopal School of Acadiana do more than learn about general environmental issues; they also get outside and participate in direct monitoring of the ecosystems around them. On February 21st and 23rd they were joined by Coastal Wetlands Planning, Protection, and Restoration Act staff to discuss coastal habitats, the mammal species that call them home, and different wildlife monitoring techniques.
On Tuesday CWPPRA staff and ESA students discussed the importance of barrier beach systems for both human and wildlife communities, and students were given training in how researchers trap small mammal populations in those locations for monitoring. After students deployed small mammal traps around the ESA Cade campus on Wednesday, CWPPRA staff returned Thursday morning to help with trap collection and see what students had captured. In addition to trapping a variety of insects drawn to the oatmeal-soybean bait and several traps which had been moved by larger animals, ESA students successfully captured a marsh rice rat (Oryzomys palustris)!
These rodents are found throughout the Gulf and mid-to-south Atlantic coasts and as far inland as Illinois and Kansas. As the name suggests, marsh rice rats are generally found in wetland areas, although drier areas with dense grasses and sedges, while not ideal habitat, are also utilized. A native species in Louisiana, marsh rice rats can even be found out on barrier islands where their omnivorous diet lets them take advantage of both terrestrial food resources and items that wash ashore. The rat captured on the ESA campus was trapped near a stream and probably forages along that water body at night. Finding a marsh rice rat on a school campus is a reminder that wetland habitats come in a range of sizes and types and that we share those habitats with many different species.