HR: 09:30h
AN: NB31C-05    [Abstracts]
TI: Wilson Creek Valley Restoration: Transformation of a Bedrock Channel to an Alluvial Stream
AU: * Parola, A C
EM: a.c.parola@louisville.edu
AF: Stream Institute, Department of Civil and Environmental Engineering University of Louisville, Louisville, KY 40292
AU: Vesely, W S
EM: william.vesely@louisville.edu
AF: Stream Institute, Department of Civil and Environmental Engineering University of Louisville, Louisville, KY 40292
AB: Wilson Creek Valley Restoration: Transformation of a Bedrock Channel to an Alluvial Stream The historically high economic value of alluvial valleys associated with agriculture, transportation infrastructure and habitation in the eastern US has resulted in the modification of virtually all alluvial stream valleys sufficiently suitable for subsistence agriculture. In stream valleys with thin alluvial veneers over bedrock, anthropogenic modification that includes increases in channel cross sectional dimensions, reduction in channel sinuosity, flood flow confinement, removal of form drag elements, and relocation of streams may transform alluvial stream reaches into bedrock reaches through channel incision processes. The effects of channel incision on infrastructure adjacent to deep alluvial systems are well known; however, exposure, flow quarrying, transport and deposition of broken bedrock pieces in valleys adjusted for transport of gravels represent serious fluvial hazards not widely recognized. In addition, the transformation from alluvial regimes to one dominated by bedrock involves changes of several important stream and wetland habitat features including substrate modification, reduction in bed topographic variation, reduced frequency of floodplain inundation, and a general groundwater lowering that adversely affects hyporheic zones. The restoration of Wilson Creek valley in central Kentucky transformed the stream channel from its anthropogenically imposed low sinuosity, confined, and relocated bedrock regime to a sinuous alluvial stream position near the valley center. The restoration demonstrates the ecological effectiveness of restoring valleys to accommodate streams to a form similar to their historic alluvial form. In addition to sediment transport, many other important aspects of stream design were considered to restore riverine habitat to a valley modified for agricultural purchases more than 80 years ago. An important restoration design component was the proximity of valley groundwater levels and aquifer thickness to support high stress period (low flow) pool and hyporheic zone habitat. Pre- and post-restoration biological data indicate an unanticipated rapid re-colonization of the restoration and an increase in fish species only months after restoration completion. Continued detailed post-restoration biological and geomorphic monitoring including bedload sampling is in-progress.
DE: 1803 Anthropogenic effects
DE: 1815 Erosion and sedimentation
DE: 1821 Floods
DE: 1824 Geomorphology (1625)
DE: 1829 Groundwater hydrology
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly