CSDMS 2016 annual meeting poster MaxDaniller-Varghese
An experimental investigation of mouth bar formation with vegetation
Wonsuck Kim, The University of Texas at Austin Austin Texas, United States. delta@jsg.utexas.edu
Abstract:
Delta networks are systems of interconnected channel-island nodes, their size and organization dictating delta morphology. When a sediment-laden channel enters slack water, it loses momentum and carrying capacity, dropping its sediment. As sediment accumulates, flow moves around it and a mouth bar island forms. While this process has been numerically modeled, physical experiments of this process have proven challenging. We present an experimental investigation using the Sediment Transport and Earth-surface Processes (STEP) basin. We made mouth bar deposits with a jet flow at a range of discharges (0.1-0.5 l/s) over intermittent flood-interflood cycles. The experiment has a flat, 5 cm thick sediment layer confined on three sides and open on the downstream end, a 5 cm flow depth above the sediment, and a backing berm at angle of repose so the opening angle can self-organize. Over the course of high and low discharge events, the deposit reworks from a parabolic to a barchanoid mouth bar.
In natural systems, vegetation plays an important role in generating and damping sediment transport, but these effects have not yet been applied to mouth bar formation and their consequences for delta island evolution. More work will be conducted on the effects vegetation has in turbulent production and the effect on sediment routing and island evolution.
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