NOAA's National Centers for Coastal Ocean Science

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How did this new sea level project come about? And where is it headed?

"Marsh organs" are devices for studying how plants respond to different amounts of tidal inundation. A strong shoreward wind at high tide covered the bottom row grasses in the organs with water. Pictured here are marsh organs measuring data at Pine Knoll Shores, near Atlantic Beach, North Carolina.

CA: We started in 2003 with funding for CO–OPS as well, and also the Coast Survey Development Lab, an R&D group in NOAA, comparing data on high and low tides with coastal and national geodetic surveys. Over time, our partnerships broadened, and the research took on an ecological focus. This collaboration led to the development of physical models beginning with a hydrodynamic tide model of Pamlico, Albemarle, Core and Bogue Sounds, and of adjacent estuarine and coastal waters using Advanced Circulation Model (ADCIRC) Finite Element Hydrodynamic Model for Coastal Oceans, Inlets, Rivers and Floodplains. This model has evolved to include recent airborne LIDAR —Light Detecting and Ranging—topographic data and bathymetric data. The resulting coastal flooding model predicts sea level rise impacts on coastal land and water. It can simulate tidal variations, wind driven tide, hurricane driven surges, and changing shoreline and inundation patterns as a result of increased sea level.

Since 2005, NOAA has been working with university partners and state managers to create ecological models that will integrate with its physical model. Now we have three separate ecologically focused sub–modeling activities underway that will take us through 2008. After that, we plan to integrate the models so they work together and then extend our approach to other coastal areas.

Why North Carolina? Certainly it's not unique in facing problems with sea level rise?

CA: Sea level rise presents a serious challenge for North Carolina. While North Carolina was chosen for the pilot because of the availability of data, other coastal states face similar problems.

Carol and the marsh organ team. Here, the growth of Spartina, commonly known as Salt water cord grass is compared to Juncus.

North Carolina has more than 300 miles of ocean beaches and more than 4,000 miles of estuarine shoreline. Much of this area is less than 20 feet above mean sea level (MSL), with much of it actually less than five feet above MSL. A rising sea level will have significant adverse effects on the state’s environment, public health and economy.

The impacts of sea level rise will vary by location and depend on a range of biophysical characteristics and socioeconomic factors, including human response. The most important physical effects of sea level rise are the gradual inundation of wetlands and low dry lands, erosion of beaches, more frequent and severe flooding, and greater salinity of rivers, bays, aquifers, and wetlands.

In general, this issue has not been a priority for many coastal communities as they plan for future growth and land use. What, for example, will the impact be for roads, bridges, sewage treatment plants, and other development now in the planning stages? Should sea level rise be a consideration for approving of home septic systems that could easily be under water 20 years from now? If the Outer Banks don’t survive, what will happen to the ecosystems and habitats along the part of North Carolina sheltered by the barrier islands? And so on.

What specifically do you hope to achieve with this project?

CA: Our goal is to give people who live along our coasts a heads–up on what to expect locally from the combined forces of sea level rise and severe weather events. Tangible products will include ecological maps, models, data, and understanding that coastal managers will be able to use in planning their long–term responses to sea level rise, and in day–to–day decisions.

These models and maps will indicate which areas are most vulnerable and most in need of immediate action. Longer term, they will help managers and planners decide which commercial activities and land use practices to encourage or enforce to mitigate the impacts.

You mentioned the need to collect detailed data on tides going back decades. What other kinds of data do you need and where are the shortfalls?

Dr. Don Cahoun, a scientist from United States Geological Survey installing a Surface Elevation Table, or SET, a portable, mechanical leveling device deployed atop a fixed vertical bench mark to measure changes in surface elevation relative to the depth of the bench mark. To prevent stepping on fragile marsh plants, the team use a network of gangplanks to get to the research location.

CA: A lot of data are needed to predict tides and how much tides are rising. At least 20 years of data are needed for this kind of work. Data collected hourly over a 50 to 60 year period translates into a huge data set. We have some bathymetric data going as far back as 1880– back when they measured water depth with a weighted line, and as recent as the 1990s when the bathymetric survey was achieved using a type of underwater radar. We are using LIDAR data to measure the vertical elevation of the land—another type of radar. Then we have to assure that the land data and the water data are all measured from the same point—a constant datum so that the measured numbers have an anchor—and can be compared with each other. These are the bare bones data used for the flooding model.

In contrast, the ecological data involve comparing aerial photos from the 1950s to the present to see how shoreline has actually changed in the past 50 years, and measuring the growth of various marsh grasses under differing inundation conditions. One of the ways that we measure marsh grass growth with using marsh organs as pictured in the photo of our field work. This organ has different species of marsh grass at various sea level elevations so that we can figure how the plants respond to various water levels, wave climates and salinity.

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You mentioned launching parallel ecological models linked to your original coastal flood model. What are these, and how do they work together?

Dr. David Furbish and Ph.D. student Susan Howell from Vanderbilt University installing a Surface Elevation Table, or SET. In this picture, Susan is preparing a metal rod prior to installation. It will be pounded into the marsh as deeply as it can go.

CA: The combined product of these models will be a system that predicts ecosystem change as a function of sea level rise. We’ve launched four separate modeling activities.

The East Carolina study team is focusing its mapping efforts in the Neuse River region. They are developing a GIS–based predictive tool to incorporate critical parameters controlling shore–one dynamics as determined by isolated shore zone studies.

The South Carolina/Vanderbilt team is looking at whether marsh building is keeping up with sea level rise. Existing models for Spartina that integrate vegetation responses to changes in mean sea level with sediment accretion and supply are being adapted to the Juncus marsh communities and conditions. Early results suggest that the grasses are keeping up.

The University of North Carolina’s Institute of Marine Sciences is focusing on the tidal area of Back and Bogue Sounds to produce habitat simulation models. That will support forecasts of the effects of variable water levels and shoreline stabilization on the structure and ecological function of sub–tidal, submerged aquatic vegetation, inter–tidal flat, oyster, and marsh habitats.

Dr. Ben Horton, a researcher from the University of Pennsylvania, is collecting sediment cores at different locations at Pine Knoll Shores to determine historic water level, salinity, pH, substrate and vegetation cover. This is done by collecting microfossil foraminifera and diatoms which occur in distinct vertical zones. This data will be used to determine changes in the Pine Knoll Shores locations over time.

The landscape model that we in the National Ocean Service are developing in partnership with East Carolina University will integrate physical and ecological models to examine the effect and extent of ecological change resulting from sea level rise and storm surge on coastal habitats. It will apply to the entire study region, mapping soils, water, and biological data into squares to answer questions like: Will habitat change? Will the landscape be dry or wet? We hope to be able to better answer those kinds of questions.

How will your models differ from other kinds of predicting tools? And who is the target audience for them?

CA: Shoreline protection and land use decisions are mostly made at the local level or on a parcel–specific basis. So we need maps that show the site–specific implications. We will be developing a suite of high–resolution mapping and modeling tools. Some planners prefer to use these tools directly. We want to make sure the tools are easy enough to use that they require minimal training to operate. Others most likely will work from hard copy maps that respond to specific scenarios that reflect the current projection for sea level rise during the next several decades they pose.

Are you hearing from the local people on what they need?

A University of North Carolina researcher is measuring the effect of sills, as shown, on marsh structure.

CA: North Carolina managers have been involved as technical advisors since the program’s inception. In 2003, we engaged management assistance from the state’s Division of Coastal Management to help with planning a research program to meet their needs.

In 2004, we convened a workshop in Beaufort, North Carolina, to obtain input from scientific and management communities. Just this past January, we held another workshop bringing together a diverse group from state and local government and nonprofit organizations to talk about the kinds of information they need and how they want it presented. We plan to stay engaged with this group through e–mail and websites and establishment of a Sea Level Rise Advisory Group.

How near are you to turning over actual products to coastal decision makers in your region?

CA: We’re now collecting data for the ecological models that will be integrated into our larger flooding model. With planned 2009 funding, and through interactions with our managers, we’ll develop the interfaces that will translate information from our large–scale model into tools decision makers can easily use.

With local interests then continuing our modeling goal is the transfer of the models to North Carolina managers—such as the state’s Climate Change Commission given its interest in sea level rise—and we’ll move further toward local managers using these newly available resources.

For instance, Doctors Peterson and Riggs, from the University of North Carolina and Eastern Carolina University respectively, are involved in our project, as is Dr. Reyes from East Carolina University, a leading North Carolina modeler. Working with RENCI through a $1.6 million grant, we’ll be able to increase computational power through use of high performance computing. We then expect to be able to predict and monitor coastal environmental and ecological changes, such as changes in land configuration and mass and habitat loss.

It’s an aggressive and exciting program with great potential, and our expectation is that it will long outlive NOAA’s own institutional and financial commitment to getting it going.