Channel Bed Adjustment Along Pool-Riffle Sequences in Gravel Bed Streams

Pool-riffle sequences are a common bedform observed in gravel bed rivers in many environments. Much research has been done in the field relating to their development, but little detailed research is available surrounding their adjustment in response to changing discharge and sediment supply. In order to overcome the difficulty involved in collecting detailed particle size, velocity, and mobility data in the field, flume experiments were conducted on a scale model of a pool-riffle sequence identified in East Creek, British Columbia for which 14 years of channel adjustment field data is available. Flume experiments were conducted at four ascending discharges and sediment feed rates, scaled to model 1.00, 1.19, 1.67, and 2.14 times the bankfull discharge. Sediment transport rates were measured over the pool and riffle and at the flume outlet. Gravel tracers were used to measure virtual velocities and to study patterns of particle entrainment and deposition over the pool and riffle. Measurements of particle size, bed topography, and near-bed velocities were also taken. In this study we will present results on structural, textural, and flow pattern adjustments and changes in entrainment and deposition patterns over pools and riffles as flow increases.