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Civil Engineering Magazine THE MAGAZINE OF THE AMERICAN SOCIETY OF CIVIL ENGINEERS

Team Developing Marsh Restoration Database

By Kevin Wilcox

Mississippi has commissioned a GIS system to identify the best, most cost-effective sites for marsh restoration projects.

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A team of engineers is examining the Gulf Coast of Mississippi to develop a GIS repository of data that can be used to prioritize sites for potential marsh restoration projects. © Dewberry, Dave Huh, photographer

April 19, 2016—The Mississippi Department of Environmental Quality (MDEQ) has hired a team of engineering firms to examine the geographic characteristics, shoreline retreat rates, and dredging activities of St. Louis Bay, Back Bay Biloxi, and the Escatawpa/Pascagoula regions of the state to help identify the most strategic and cost-effective sites for marsh restoration and living shoreline projects.

"Similar to many shorelines along the Gulf Coast, there has been significant erosion—some storm induced, some due to the dredging of navigation channels nearby," says Cheryl Ulrich, P.E., an ecosystem restoration specialist for Dewberry, a professional services firm headquartered in Fairfax, Virginia, that is part of the team. "Over time these natural and anthropogenic actions have contributed to the depletion of coastal marshes in our bay and estuarine systems. With a lot of funding coming through different avenues from the Deepwater Horizon oil spill settlement, the gulf states are trying to plan for future coastal restoration projects."

The project is being funded with a $21.5-million grant from the Gulf Environmental Benefit Fund, which is administered by the National Fish and Wildlife Foundation (NFWF). The grants are intended to support projects that remedy the harm from the 2010 oil spill or reduce the risk of future coastal harm.

The team, which is led by Brown, Mitchell & Alexander, of Gulfport, Mississippi, also includes South Coast Engineers, of Fairhope, Alabama; BMI Environmental Services, of Gulfport, Mississippi; and GAEA, of New Orleans. The team will develop a geographic information system (GIS) repository of data with layers of site-specific information about the state's key coastal areas. That data will include the dredging schedules for nearby shipping and navigation channels. The goal of the project is to use the GIS system to recommend high-priority sites for potential marsh restoration projects. "One of the first tasks you do on any coastal engineering project is look at what has been done before and what exists in terms of data, surveys, documents, and prior studies for these project sites," Ulrich says. Currently, the team is in the beginning stage of the project and is actively identifying potential GIS layers and isolating gaps in the existing data.

When examining potential restoration sites, Ulrich notes that the team will first look at erosion patterns to determine which shorelines are experiencing critical loss and identify the areas in which that loss exposes coastal infrastructure to heightened risk. "It makes more sense to try to build a living shoreline or marsh in front of significant infrastructure, to protect it," Ulrich explains. "In the long run, research shows that natural coastal buffers better protect uplands and infrastructure from storms and surge, which saves you the cost of having to rebuild.

"The other big factor here is where to get the sources of sediment for coastal restoration projects," she adds. "How far away from these critical marsh creation sites are potential sources of sediment? Is it cost prohibitive to try to get the material to the site?" The GIS system will eventually contain all the elements needed to answer those questions and provide a reliable cost-benefit analysis of the sites.

By determining the coastal processes of the regions, the MDEQ will be able to improve its understanding of how material is transported throughout Mississippi's bays and estuaries, targeting marsh restoration efforts to sites at which they can provide a lasting impact, Ulrich notes. "The worst thing you can do is go spend a lot of money and put material in the wrong coastal location and the next thing you know, it's totally out of the system," she says.

The GIS database under development will also include the general permitting requirements for the sites. Ulrich notes that in some areas, obtaining permits for marshes and living shoreline projects takes considerably longer and is more costly than obtaining permits for such traditional interventions as bulkheads.

"It's great that the MDEQ is planning for future coastal restoration projects by inventorying current, past, and known future activities and information pertaining to the state's coastal resources," Ulrich says. "By formalizing the criteria and guidelines for marsh site selection, it gives the state a rationale for prioritizing future coastal projects and initiatives." Additionally, future marsh restoration efforts will involve extensive outreach to stakeholders and the public. Together these clear guidelines create a more transparent process that reduces disagreements about spending.

Ulrich says the difficulty in planning marsh restoration sites and living shoreline projects is compounded by the threat of rising sea levels from climate change, which has some small communities along the Gulf Coast considering relocation. "Is that going to happen to Miami or is that going to happen to Gulfport? Probably not, but when it's time to upgrade critical infrastructure, coastal communities are moving it inland," Ulrich says. "At the end of the day, it's all about economics. When you look at the economics of a community on the coastline, that's a big factor. When companies look at investing a lot of money in your town, they want to be assured that it's going to be there for a while."

The GIS coastal inventory system is slated for completion within six months, with an additional six months dedicated to a rollout of the system to stakeholders, training, and any needed modifications. The information in the database will not only help guide site selection for future marsh restoration projects in Mississippi, but it will also serve as a repository for information on those projects moving forward.

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