Remedies Must Work in a Dynamic Natural System
Complex Solutions Rely on Science and Engineering
The mission sounds simple: Restore Louisiana’s wetlands. And, on the surface, the methods to accomplish it sound equally simple: erect barriers to stop erosion, import sediment to raise elevation, divert river water to nourish degraded marshes.
But the solutions’ seeming simplicity belies the complexity of restoring Louisiana’s dynamic coastal ecosystem. Will the underlying soils support the weight of a barrier? What marine organisms will need to migrate through that barrier? About that sediment — how high should it be stacked? How fast will it compact? What kind of vegetation does it need to support? And diversions — how much water should be released? How fast should it flow? How will plant and animal communities change in a freshened marsh?
Even the simple statement of mission raises myriad questions: restore to what condition? For how long? And at what cost socially as well as financially? Yet, facing the disappearance of hundreds of square miles of coastal wetlands, Louisiana — indeed, the nation — has no choice but to grapple with these questions.
Structures as simple as rock barriers can effectively halt some causes of land loss, but in the dynamic coastal ecosystem even such straightforward measures as using rocks to buffer wave action can alter the hydrology, biology — even the chemistry of the wetlands they protect.
Sharon Coogle, Koupal Communications
A pioneer in environmental restoration, the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) has confronted such questions and sought answers based on the best scientific and engineering knowledge available. On each CWPPRA project, scientists and engineers bring up-to-date understanding of coastal ecosystems and current thinking about restoration techniques and collaborate to set goals, develop designs and monitor results.
Science Describes the Goal, Engineering the Means
When a location is considered for a CWPPRA project, scientists join engineers to visit the proposed site and recommend conditions to set as project goals, such as the depth and salinity of the water, the stability of the shoreline, or the kind and coverage of vegetation.
“We rely on scientists to provide us with the in depth, empirical data we need to improve restoration projects,” says Rick Raynie, a coastal resources senior scientist with the Louisiana Department of Natural Resources (LDNR) and co-chair of CWPPRA’s Monitoring Workgroup. “For example, there is widespread anecdotal evidence that wetlands dampen storm surge, but to incorporate that into restoration plans we need to know how vegetation dissipates wave energy, what species of vegetation to plant and at what density for maximum results.”
How quickly does drought affect salinity levels? Does a high nutrient count inevitably result in algal blooms? What is the ideal hydrologic flow for sediment delivery? Analysis of water samples taken back to the laboratory contributes to unlocking even the smallest secrets of the wetlands.
Dr. Robert Lane, LSU
In turn, engineers tell scientists what is possible to build — if the subsoil will support hard structures such as rock barriers, if sufficient fresh water can be diverted to nurture the preferred vegetation, if pipelines can traverse the distance between sediment source and delivery site. “There is a lot of feedback and interaction between the two groups to shape projects, determine their feasibility and modify them to provide the desired benefits,” says Raynie. “Scientific evaluations influence management decisions, and project data contributes to scientific understanding of the complex coastal ecosystem.”
Keeping CWPPRA Current
CWPPRA’s process involves scientists and engineers in every project phase. Personnel from CWPPRA-affiliated government agencies provide expertise by serving on CWPPRA committees, including the following:
- the Environmental Workgroup, charged with reviewing candidate projects, recommending ways to achieve and enhance wetland benefits, and estimating projects’ annualized benefits
- the Monitoring Workgroup, which develops standard operating procedures and oversees implementation of field monitoring programs
- the Engineering Workgroup, providing engineering standards, quality control, support and review of cost estimates for numerous aspects of proposed projects
Additionally, project teams include scientists from LDNR who prepare the ecological review document during a project’s engineering and design phase. Using monitoring data, engineering designs, and scientific literature, they evaluate project goals from a biological and ecological perspective and assess the likelihood of achieving the proposed biotic benefits and desired ecological responses.
Monitoring the effects of projects on wetland conditions provides data used to select future restoration techniques and to adjust management practices. Here, a scientist spreads feldspar on the marsh surface to provide a marker for measuring land accretion in future core samples.
Dr. Robert Lane, LSU reviews.
To be sure its projects are based on the best science and engineering available, CWPPRA may contract with private firms, independent scientists and scientists from Louisiana’s universities who serve on CWPPRA’s Academic Advisory Group (AAG).
The AAG works with other CWPPRA committees to evaluate proposed projects, suggest modifications, and develop and implement field monitoring programs that provide data for ecological reviews “We help describe how a wetland would change if a project is built, or if it is not built,” says Dr. Jenneke Visser, associate research professor at Louisiana State University and current chair of the AAG. “Evaluation procedures differ for different types of wetlands, and we are always adjusting them to adopt the most current scientific findings.”
The AAG brings the latest research in coastal restoration to the field, says Kevin Roy, a biologist with the U.S. Fish and Wildlife Service and chair of CWPPRAs Environmental Workgroup. Using scientific literature, monitoring and other data, the AAG contributes to reviews that determine whether a proposed solution makes sense and incorporates the appropriate science in its engineering.