Document Type

Article

Journal/Book Title/Conference

Earth, Surface, Processes and Landforms

Publisher

Wiley

Publication Date

1-23-2019

Keywords

migration, erosion, river, measurement, scale

First Page

1

Last Page

35

Abstract

Accurately measuring river meander migration over time is critical for sediment budgets and understanding how rivers respond to changes in hydrology or sediment supply. However, estimates of meander migration rates or streambank contributions to sediment budgets using repeat aerial imagery, maps, or topographic data will be underestimated without proper accounting for channel reversal. Furthermore, comparing channel planform adjustment measured over dissimilar timescales are biased because short‐ and long‐term measurements are disproportionately affected by temporary rate variability, long‐term hiatuses, and channel reversals. We evaluate the role of timescale dependence for the Root River, a single threaded meandering sand‐ and gravel‐bedded river in southeastern Minnesota, USA, with 76 years of aerial photographs spanning an era of landscape changes that have drastically altered flows.

Empirical data and results from a statistical river migration model both confirm a temporal measurement‐scale dependence, illustrated by systematic underestimations (2–15% at 50 years) and convergence of migration rates measured over sufficiently long timescales (> 40 years). Frequency of channel reversals exerts primary control on measurement bias for longer time intervals by erasing the record of observable migration. We conclude that using long‐term measurements of channel migration for sediment remobilization projections, streambank contributions to sediment budgets, sediment flux estimates, and perceptions of fluvial change will necessarily underestimate such calculations. © 2019 John Wiley & Sons, Ltd.

Comments

This is the peer reviewed version of the following article: Donovan, M., and Belmont, P. ( 2019) Timescale dependence in river channel migration measurements. Earth Surf. Process. Landforms, https://doi.org/10.1002/esp.4590., which has been published in final form at https://doi.org/10.1002/esp.4590. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

Available for download on Thursday, January 23, 2020

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