Smartrock transport during snowmelt floods: Discharge controls on rest
scaling from seconds to seasons
Abstract
We quantify how changes in natural flood discharge control bedload rest
time distributions and may influence particle diffusion through mountain
river networks. We embedded accelerometers and gyroscopes into
artificial cobbles deployed in Halfmoon Creek, Colorado, USA, and
measured bedload transport during 28 daily snowmelt flood hydrographs in
2015. From the motion sensor data we calculate motion and rest
distributions over ~6 orders of temporal magnitude, from
~2 seconds to ~1 month. Motion durations
follow a thin-tailed exponential distribution. Rests >12
hours can be well fit by both truncated Pareto distributions and
exponentially-tempered Pareto distributions, suggesting ambiguity in
whether rests remain heavy-tailed or transition to thin tails at even
longer timescales. Rest time scaling varies not only with timescale but
also with flow intensity, becoming less heavy-tailed as shear stress
increases. A rest time scaling break at ~12 hours may be
caused by daily discharge cyclicity.