See more from this Division: Topical Sessions
See more from this Session: Sediment in Fluvial Systems: Production, Transport, and Storage at the Watershed Scale II
Abstract:
Where an active channel crosscuts an incompletely filled abandoned channel, natural-levee sediment may partially fill the abandoned channel. At one location the Red River migrated across a previous cutoff and deposited a natural levee over the cutoff-bar. In the abandoned channel depression beyond the natural levee, silty sediment from the nearby active channel overlies more clayey sediment from a previous more distant active channel. This coarsening upward fill accumulated in <170 years.
Where an active channel eroded past a cutoff bar to an abandoned channel depression, sediment may crevasse through the depressed channel wall during floods and partially fill the abandoned channel. This crevasse deposit is interbedded sandy silt to mud up to 1.4 m thick in proximal locations and 0.8 m thick in distal locations and is within normal clayey channel fill that accumulates prior to and post crevassing. This highly variable abandoned channel fill has accumulated in <765 years.
See more from this Division: Topical Sessions
See more from this Session: Sediment in Fluvial Systems: Production, Transport, and Storage at the Watershed Scale II