Unit stream power, stream power per unit channel length, and total boundary shear stress were used to assess probable zones of river-sediment transport and storage following a large landslide into the Deer Creek basin, Skagit County, Washington. Since an initial deep-seated failure in glacial deposits in 1983 and a larger failure in 1984, the DeForest Creek landslide has introduced fine (±75% finer than coarse sand) sediment into the main channel of Deer Creek. The influx of sediment has caused infilling of void space in channel gravel by sand and silt, increased bank erosion, and increased slump activity adjacent to the stream. Bankfull discharge (considered to be a channel-forming discharge) was calculated for each of 114 reaches in the 13.4 km study reach. The discharges were used in conjunction with thalweg slopes, bankfull widths, and active-channel depths to calculate unit stream power, stream power per unit channel length, and total boundary shear stress. Analysis of unit stream power for successive reaches of Deer Creek indicates that this variable is sensitive to the degree of bedrock control on channel morphology. In turn, unit stream power exerts a significant control on sites of bank erosion, channel aggradation, and degradation; and it appears to control, at least in part, sites of sediment storage. Thus, unit stream power can help locate reaches most likely to change as Deer Creek adjusts to the increased sediment load from the DeForest Creek landslide
