Channel Migration and Incision on the Beatton River

New field data relating to bend migration rates with bend radius of curvature to channel width ratios (rmw) for the Beatton River confirm the form of the relationship the writers described in 1975, although there is more variance than our initial results suggested. Recent data from forest successions on the floodplains of a variety of migrating rivers show that channel migration is a discontinuous process within any single bend. This means that predictions of migration rates for individual bends, based on short-term measurements using erosion pins or aerial photographs, are highly suspect. These variations in migration rate are likely a response to fluctuating channel widths over time because of a short-term imbalance between the rate of cutbank erosion and the rate of point-bar sediment accumulation. Finally the examination of new evidence for channel incision on the Beatton River shows that the river is downcutting at a rate of about 2 mm yr, not at 10 mm yr as reported earlier.