Bedload transport of mud by floccule ripples—Direct observation of ripple migration processes and their implications

Abstract

Flume experiments have shown that muds can be transported in bedload as floccule ripples and deposited at current velocities that would suffice to transport and deposit sand. A new set of experiments provides firsthand observations of the processes that shape and propagate mud ripples. Sediment is transported over the stoss side in the form of diverging boundary-layer streaks, the carriers of the bulk of the bedload floccule freight. At the brinkline these streaks become point sources of sediment that feeds avalanches of floccule-rich sediment lobes. These propagate down the slip face like classic mudflows on a hillside. Geometries of ripples are very similar to those produced in sandy sediments, even though the floccule ripples contain as much as 90 vol% water.