Departmental Papers (EES)

Document Type

Journal Article

Date of this Version

9-16-2014

Publication Source

Geophysical Research Letters

Volume

41

Issue

17

Start Page

6152

Last Page

6159

DOI

10.1002/2014GL060525

Abstract

Sediment tracers are increasingly employed to estimate bed load transport and landscape evolution rates. Tracer trajectories are dominated by periods of immobility (“waiting times”) as they are buried and reexcavated in the stochastically evolving river bed. Here we model bed evolution as a random walk with mean-reverting tendency (Ornstein-Uhlenbeck process) originating from the restoring effect of erosion and deposition. The Ornstein-Uhlenbeck model contains two parameters, a and b, related to the particle feed rate and range of bed elevation fluctuations, respectively. Observations of bed evolution in flume experiments agree with model predictions; in particular, the model reproduces the asymptotic t−1 tail in the tracer waiting time exceedance probability distribution. This waiting time distribution is similar to that inferred for tracers in natural gravel streams and avalanching rice piles, indicating applicability of the Ornstein-Uhlenbeck mean-reverting model to many disordered transport systems with tracer burial and excavation.

Copyright/Permission Statement

Copyright © 2014 by the American Geophysical Union.

Keywords

sediment transport, bed evolution, waiting times, sediment tracers, stochastic processes, Ornstein-Uhlenbeck

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Date Posted: 11 November 2016

This document has been peer reviewed.