BATON ROUGE, La. (Aug. 30, 2022) – A new study published in the Journal of Environmental Management shows that coarser grained sands used in coastal restoration projects produce higher economic advantages over cheaper, fine-grained sand over the long-term.
“The economics of sediment quality on barrier shoreline restoration,” combines the science of sand movement by coastal currents with economic benefit analysis to compare the long-term economic stability of shoreline and barrier island restoration projects when using fine versus coarser grained sands. The study finds that even though finer grained sands are often available closer to restoration project sites and therefore cheaper to use, coarser grained sands require much stronger currents to be moved off a site which provides increased stability and better “bang for the buck” in the long-term even under tropical storm conditions.
With $22 billion of the state’s $50 billion Coastal Master Plan slated for sediment dredging to do barrier shoreline and marsh restoration, the availability and cost of extracting and moving this sediment to a restoration site has been the most important factor in considering project cost and feasibility. Sediment inventory maps estimate the total volume of Louisiana-adjacent Outer Continental Shelf sand at nearly two billion cubic meters, with 60% of this material considered recoverable under current technological and regulatory constraints. Until recently, access to these offshore deposits was considered economically infeasible in comparison to lower quality, finer grained nearby sand sources.
However, in the new study led by Rex Caffey, a resource economist with the Louisiana State University Agricultural Center and the Louisiana Sea Grant College Program, the findings appear to provide economic confirmation to the longstanding notion held by geomorphologists that “grain-size matters.” The increased stability afforded by using coarser grained sand to restore barrier islands means these features will maintain land area into the future much longer than if restored with finer sands. In addition, the study suggests that there are more comprehensive ways to determine the cost/benefit of a project beyond just the construction cost.
Project partners include Daniel Petrolia, professor in the Department of Agricultural Economics at Mississippi State University, Mike Miner, director of Applied Geoscience at The Water Institute of the Gulf; Ioannis Georgiou, director of Coastal and Deltaic Systems Modeling at The Water Institute of the Gulf; Hua Wang, assistant professor in the Department of Agricultural Economics & Agribusiness at Louisiana State University; and Brittany Kime, Department of Earth and Environmental Sciences at the University of New Orleans.
The three-year study was sponsored by the Bureau of Ocean Energy Management (BOEM) and funded by an award administered through the Louisiana State University Coastal Marine Institute. Read the article in the Journal of Environmental Management here. Read more about the work and how it developed here "Coastal Restoration Economics: A Granular Look at Project Performance."
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