NC State researchers hope to identify land for conservation along the Cape Fear watershed
North Carolina State University researchers are investigating how riparian buffers — the forests and vegetation that surround a water source — impact water quality in the Cape Fear watershed.
The team of researchers is looking at the health of the Cape Fear watershed. Elly Gay, a Ph.D. student in the Department of Forestry and Environmental Resources at NC State University, is looking at how both global and local factors impact the watershed.
“Coastal health protection is very important right now and not only under the context of global change but also considering more regional patterns in development, the southeast is rapidly developing and changing. And that can have implications for our coasts,” Gay said.
The Cape Fear watershed is the largest in the state. It spans all the way from Greensboro to Wilmington — it's entirely contained within North Carolina.
Caroline Zuber, an undergraduate student at NC State who works along with Gay on the project, explained the land usage within the river basin.
“It's about 20% agriculture more toward the east of the watershed. And then we know that it's about 10% developed, so that includes those towns and those big cities throughout the watershed. And it's also about 40% forested,” said Zuber.
Gay and Zuber are looking at what contributes to the quality of the watershed. Their hypothesis is that the strategic placement of forested and vegetative buffers helps reduce runoff from farming and development into the river and its tributaries.
Dr. Katherine Martin is an assistant professor in the Department of Forestry and Environmental Resources at NC State University. She’s also a faculty affiliate with the Center for Geospatial Analytics. Martin is working on the strategic buffer project with Gay and Zuber.
“To protect the coastal area, the buffers would need to be concentrated in the southeastern part of the watershed closer to the coast,” said Martin.
Martin, Zuber, and Gay are using a “FUTURES” computer model, developed by NC State researchers at the Center for Geospatial Analytics, to simulate the Cape Fear watershed. For their research project, they’ll introduce variables like riparian buffer scenarios, future development scenarios, sea-level rise, and the level of carbon dioxide emissions into their model.
After they complete their analyses, they hope to identify areas where water quality might be particularly vulnerable. Gay said this would be through the context of increased development and farmland that would produce additional nitrogen, phosphorus, and suspended sediment concentrations.
Once they establish where these areas are, the researchers can then introduce strategic buffers into these “hotspot areas,” which in turn could affect water quality downstream.
The Possible Impact of Riparian Buffers
The researchers said it’s likely strategic riparian buffers could lessen the impacts of climate change, for example reducing the effects of future hurricanes. Buffers can also help prevent heavier rains from washing more sediment downstream.
“If you think about it, if you have more water flowing within the watershed into the river, that's going to pick up way more sediment from nearby land, or even fertilizers from agriculture, and things like that,” said Zuber.
Dr. Martin said a changing climate will likely adversely impact the watershed.
“We do expect more extreme precipitation events, so bigger rainfalls, and the other thing is that we are also concerned about increasing dry periods. And either of those extremes has an effect on water quality because if we have less water in the system, we have less dilution of nutrients and sediment. So we're looking to try to find a way to mitigate both of those extreme scenarios with buffers,” said Martin
Both New Hanover County and the City of Wilmington have to follow regulations on conservation areas outlined in the Coastal Area Management Act, or CAMA. Typically, the buffers in these environmentally sensitive areas or areas of environmental concern (AECs) are 30 feet wide, but according to Gay, other state river basins have more stringent rules.
“In North Carolina, a common riparian buffer width is 50 feet, that's actually state-mandated throughout the Neuse River Basin. So for the Cape Fear, it's going to be interesting to look at how all these strategic buffer widths, potentially varying widths affect downstream water quality,” said Gay.
Rebekah Roth, the planning director for New Hanover County, said the county’s Unified Development Ordinance has additional controls on development which require setbacks for buildings located near conservation land. Roth said the setbacks can “range 25-100 feet from the conservation space, depending on the specific resource type and proposed development.”
Anna Reh-Gingerich, the watershed coordinator for the City of Wilmington, said the Cape Fear River Basin “doesn’t have specific buffer rules underNC DEQ’s riparian buffer protection program, but the city does have regulations in the Land Development Code (LDC) regarding setbacks and developments with city limits.”
In addition to protecting the watershed, there are other reasons to protect these areas. Dr. Martin said putting in buffers could also contribute to cutting down on water utility pricing.
“It's also likely that if we have higher quality water that enters the water treatment plant the cost of treating the water will be lower. So if you have more sediment, the water treatment plant has to work harder to produce the finished water at the point where people want to drink it,” said Martin.
And there’s more at stake than just ensuring drinking water quality.
“But if we want to continue using water for recreation, if we want to continue the economic benefits of fisheries, if we want to have healthy coastlines and beaches, then we have to look at the system more holistically,” said Martin.
Dr. Martin, Zuber, and Gay hope to present their research to NC Sea Grant and publish their findings in a scientific journal at the end of this year.
The results would identify "hotspots" for buffer preservation — and would show their effects on water quality.