Tulula Wetlands - Stream Restoration

Restoration of Tulula Creek

Director of Research: Dr. Kevin K. Moorhead

Graduate Student Research Assistant: Duncan Quinn, Department of Forestry, North Carolina State University.

The primary focus of restoration at Tulula is to restore the historic site hydrology that was partially altered when the channel of Tulula Creek was dredged. Tulula Creek originally had a meandering, slightly entrenched channel with a low width-to-depth ratio and an average bankfull cross-sectional area of 1.4 m². Since dredging, the channel is a gully-type channel that is highly entrenched with a sinuosity less than 1.1.

The NCDOT hired a contractor to construct a meandering channel (1.9 km in length) across the floodplain to recreate the pre-disturbance condition of stream flow. The design of the new channel was partially based on the physical characteristics of a relic channel found mainly at the lower end of the site. The contractor used the relic channel, wherever practical, as part of the new meandering channel. Spoil removed during construction of the new channel will be used to partially backfill the old channel when possible. The footprint of the new channel has been completed, and the contractor will join the separate segments of the new channel together by crossing the existing Tulula Creek in the spring of 2001.

The banks of the new channel are being protected from streambank erosion with a natural fiber matting that covers the sides of the channel banks and a half meter of the adjacent floodplain. To increase the protection of stream banks, a contractor installed coir fiber rolls along the bottom of the outside banks of constructed meanders, and they planted live stakes of willow (Salix spp.) or silky dogwood (Cornus amomum Mill.) on the sides of banks and on the adjacent floodplain. The contractor installed random root wads in the channel banks to improve fish habitat. The exposed soils in the disturbed corridor of the new channel were seeded with a mixture of annual grasses, including winter rye and switchgrass. The seeded grasses survived in drier (higher) portions of the floodplain but wetter (lower) areas of exposed soils were quickly colonized by wetland species. The corridor of the new channel will be planted with canopy tree species after the channel segments are connected.

Concurrent with construction of the new channel, the contractor blocked the outlets of drainage ditches and partially refilled the ditches with adjacent spoil. We intentionally left segments of these drainage ditches to collect water to serve as amphibian habitat. Recreating the meandering channel should decrease water velocity, which, coupled with the backfilling of drainage ditches, should raise the level of the water table across the floodplain and allow for more frequent overbank flooding. The contractor also partially backfilled ten of the 11 golf ponds with spoil removed during their construction to create vernal pond conditions.


	Restoration of Tulula Creek
	Director of Research: Dr. Kevin K. Moorhead Graduate Student Research Assistant: Duncan Quinn, Department of Forestry, North Carolina State University.
	The primary focus of restoration at Tulula is to restore the historic site hydrology that was partially altered when the channel of Tulula Creek was dredged. Tulula Creek originally had a meandering, slightly entrenched channel with a low width-to-depth ratio and an average bankfull cross-sectional area of 1.4 m². Since dredging, the channel is a gully-type channel that is highly entrenched with a sinuosity less than 1.1. The NCDOT hired a contractor to construct a meandering channel (1.9 km in length) across the floodplain to recreate the pre-disturbance condition of stream flow. The design of the new channel was partially based on the physical characteristics of a relic channel found mainly at the lower end of the site. The contractor used the relic channel, wherever practical, as part of the new meandering channel. Spoil removed during construction of the new channel will be used to partially backfill the old channel when possible. The footprint of the new channel has been completed, and the contractor will join the separate segments of the new channel together by crossing the existing Tulula Creek in the spring of 2001. The banks of the new channel are being protected from streambank erosion with a natural fiber matting that covers the sides of the channel banks and a half meter of the adjacent floodplain. To increase the protection of stream banks, a contractor installed coir fiber rolls along the bottom of the outside banks of constructed meanders, and they planted live stakes of willow (Salix spp.) or silky dogwood (Cornus amomum Mill.) on the sides of banks and on the adjacent floodplain. The contractor installed random root wads in the channel banks to improve fish habitat. The exposed soils in the disturbed corridor of the new channel were seeded with a mixture of annual grasses, including winter rye and switchgrass. The seeded grasses survived in drier (higher) portions of the floodplain but wetter (lower) areas of exposed soils were quickly colonized by wetland species. The corridor of the new channel will be planted with canopy tree species after the channel segments are connected. Concurrent with construction of the new channel, the contractor blocked the outlets of drainage ditches and partially refilled the ditches with adjacent spoil. We intentionally left segments of these drainage ditches to collect water to serve as amphibian habitat. Recreating the meandering channel should decrease water velocity, which, coupled with the backfilling of drainage ditches, should raise the level of the water table across the floodplain and allow for more frequent overbank flooding. The contractor also partially backfilled ten of the 11 golf ponds with spoil removed during their construction to create vernal pond conditions.