The geomorphic legacy of splash dams in the Southern Oregon Coast Range.

摘要

Splash dams were in-stream structures that were used to facilitate log driving in the Oregon Coast Range (OCR) between 1880 and 1957. This study explores the potential legacy impacts of "splashing" on stream morphology in Camp Creek and the West Fork Millicoma in the Southern OCR. Field data on stream morphology, GIS analysis, and hydraulic modeling were used in a paired-reach and paired-basin approach to determine legacy impacts on stream widths, depths, cross-sectional shapes, wood accumulation and sediment size. The paired-reach approach did not demonstrate significant differences up- or downstream of past dam locations. The paired-basin approach indicates that "splashing" is associated with narrower streams and less fine sediment, although it is not clear whether this difference reflects legacy impacts of splash dams or other factors driving variations between basins. Splash dam releases significantly exceeded 100-yr flood magnitudes in headwater regions and were comparable to 100-yr flows in lower reaches.