Keeping buffers of trees or other greenery around waterways in areas near Raleigh that are expected to see more future development could help slow rushing streams during wet conditions and keep them flowing during dry ones.
However, North Carolina State University researchers behind a recent study cautioned that these so-called "riparian buffers" would not be a panacea for water management as development grows and the climate warms and wetter.
Forests can help manage water amid the development
Lukasz Szmigiel/Unsplash
According to Katherine Martin, assistant professor of forestry and environmental resources at NC State, forests can filter water and slow it down to prevent floods or keep water levels up during droughts.
Alternatively, in urban areas with more paved surfaces, stream flows can be more extreme.
Riparian buffers are one tool for urban water management.
The study projected average stream flow for the Upper Neuse River Watershed between 2017 and 2060, a watershed that begins in Durham, feeds into Falls Lake to supply water to Raleigh, and drains through to Goldsboro.
They tested a "business as usual" scenario with existing forest or greenspace, which includes a 50-foot state-mandated buffer area, as well as many areas that were exempted, to see how they'd impact stream flow.
They also considered a scenario with 50 feet of forested buffers throughout the entire watershed, as well as a scenario with 100 feet of forest buffers.
The researchers discovered that daily streamflow across the watershed would increase on average. They predicted that without buffers, average daily stream flow would increase by up to 28%.
Furthermore, they discovered that buffers were associated with larger reductions in stream flow in some of the most developed areas during wetter conditions.
In addition, they discovered that buffers had mixed results during dry spells. In some areas, buffers were actually linked to lower daily stream flow during dry spells, which is the opposite of what they would expect.
Buffers helped to maintain stream flow in an area of the watershed with the most future development, as well as water levels in areas that have not yet been developed.
The effects, however, were not as dramatic as expected, and there was little difference when the 50-foot and 100-foot buffers were compared.
"This suggests that buffers can play a role in mitigating extremes in stream flow, but it can't be the only strategy," Martin said.
"If we want to maintain high water quality in the future, we need a comprehensive plan that includes not only riparian buffers but more and larger green spaces, which have numerous benefits other than water," she added, as per ScienceDaily.
A riparian forest buffer is an area adjacent to a stream, lake, or wetland that is managed differently than the surrounding landscape, primarily to provide conservation benefits, as per the USDA.
Riparian buffers can also be managed to include trees and shrubs that produce a harvestable crop in addition to providing conservation benefits, though this is less common.
Buffers are used in a variety of settings, including agriculture, row crop, range, suburban, and urban.
Riparian forest buffers on public and private lands are supported by a number of state and federal programs.
Riparian forest buffers can provide a variety of benefits, such as filtering nutrients, pesticides, and animal waste from agricultural land runoff, stabilizing eroding banks, filtering sediment from runoff, providing shade, shelter, and food for fish and other aquatic organisms, providing wildlife habitat and corridors for terrestrial organisms, protecting cropland and downstream communities from flood damage, and producing income from farmland that is frequently flooded or has previously been flooded.
Moreover, riparian forest buffers can be incorporated into landscape-scale green infrastructure plans to serve a variety of functions, especially along the rural-urban interface.
Green infrastructure is a conservation strategy that entails creating a network of green spaces to benefit both people and wildlife.
A variety of factors can have an impact on the effectiveness of riparian forest buffers in meeting these goals.
Site conditions such as adjacent agricultural practices and crop types, stream size, topography, and soils; landscape conditions such as watershed position, adjacent land use, and buffer continuity; and other conditions such as markets and public interest are examples of these.
Riparian forest buffer planning and design are critical for improving riparian buffer effectiveness.
