Bed load transport regime of a small forest stream

Bed load transport in a small gravel‐bedded stream on Chichagof Island, Alaska, was measured for 33 autumn storm flows during 1980 through 1985 to determine temporal and spatial trends within a riffle‐pool‐riffle sequence. The transport of fine sediment was more frequent than coarse sediment. Scouring of coarse material in the reach appeared to be triggered only by high flows with Tr ≥ 5 years. Within a given storm season, both antecedent storm history and cumulative flow (above the threshold for bed load transport, 0.25 m3 s−1) influenced bed load transport; however, the effects of these seasonal factors changed from year to year, presumably in response to storage and release of sediment around large organic debris upstream. Hysteresis loops existed in bed load transport versus flow plots for many storms. Fine bed load material was more subject to such differential transport over the storm hydrograph than was coarse material. During the 6‐year period, both riffles scoured along most of the channel width while the middle portion of the pool filled.