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PINE VALLEY COUNTRY CLUB New Hanover County, NC Urban development takes a heavy toll on creeks, streams and rivers throughout the nation. The increase in impervious surface combined with channel constriction can result in streambank erosion each time it rains. Thousands of miles of streams in North Carolina are unstable and eroding, contributing large volumes of sediment to many stream systems. Natural channel design works to establish a stable dimension, pattern and profile based on fluvial geomorphology principles. Natural channel design has been widely demonstrated in the mountains and Piedmont of North Carolina with varying degrees of success. However, this restoration approach has not been well tested in the coastal plain. Pine Valley is a first-order tributary on a golf course in Wilmington, N.C. This previously ditched channel has been re-meandered through the golf course, increasing stream length by 15%. This project represents the first natural channel design restoration for coastal North Carolina and will serve as a model for further restoration on the golf course. The design addressed adjustments to geomorphic features, including riffle-pool sequence, bankfull channel dimension, floodplain width, meander geometry, sinuosity and slope. Phase I of the stream restoration included the construction
of a narrow and deep bankfull channel to improve stream efficiency and
aquatic habitat. The floodplain was widened to slow the water and reduce
erosive forces at high flow. The stream was re-meandered through the new
floodplain to dissipate energy, restore natural bed features, and improve
the aesthetics of the stream. To prevent future erosion, improve streamside
habitat, and provide shade, the floodplain and banks were planted with
a mix of native wetland plants, grasses, low growing shrubs, and trees
that can survive periodic inundation. The vegetation was located keeping
the golf course in mind with taller trees being placed on the edge of
fairways. Log cross vanes and root wads were installed for grade control,
to help prevent future erosion in meander bends, improve aquatic habitat,
and protect two concrete cart bridges. Log floodplain sills were installed
in tight radius meander bends to prevent potential short-circuiting of
flow during flooding events. In addition, two small bioretention areas
were constructed to intercept existing drainage depressions, prevent slope
failure, and provide minor stormwater retention and infiltration.
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Pine Valley before
restoration
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Pine Valley after
restoration (Phase I)
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Riffle-pool
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Log Vane
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Golf course projects such as Pine Valley can often present revegetation challenges as compared to rural projects. The vegetation restoration plan for the riparian corridor along the stream at Pine Valley had to account for a sewer line, view sheds along fairways, and cart crossings. Some areas were planted with taller trees, while areas such as fairways were planted with shrubbier species that could be pruned. At the request of the club, willow trees were planted alongside the cart path crossing for aesthetic purposes. Several showy shrubs, including Hibiscus, were planted for their pretty blooms. Pine Valley is an example of a restoration project that incorporates vegetative aesthetics as well as function and stability. |
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