Quantification of bedform dynamics and bedload sediment flux in sandy braided rivers from airborne and satellite imagery

Robert J.P. Strick, Philip J. Ashworth, Gregory H. Sambrook Smith, Andrew P. Nicholas, James L. Best, Stuart N. Lane, Daniel R. Parsons, Christopher J. Simpson, Christopher A. Unsworth, Jonathan Dale

Research output: Contribution to journalArticle

2 Citations (Scopus)
3 Downloads (Pure)

Abstract

Images from specially-commissioned aeroplane sorties (manned aerial vehicle, MAV), repeat unmanned aerial vehicle (UAV) surveys, and Planet CubeSat satellites are used to quantify dune and bar dynamics in the sandy braided South Saskatchewan River, Canada. Structure-from-Motion (SfM) techniques and application of a depth-brightness model are used to produce a series of Digital Surface Models (DSMs) at low and near-bankfull flows. A number of technical and image processing challenges are described that arise from the application of SfM in dry and submerged environments. A model for best practice is presented and analysis suggests a depth-brightness model approach can represent the different scales of bedforms present in sandy braided rivers with low-turbidity and shallow (< 2 m deep) water. The aerial imagery is used to quantify the spatial distribution of unit bar and dune migration rate in an 18 km reach and three ~1 km long reaches respectively. Dune and unit bar migration rates are highly variable in response to local variations in planform morphology. Sediment transport rates for dunes and unit bars, obtained by integrating migration rates (from UAV) with the volume of sediment moved (from DSMs using MAV imagery) show near-equivalence in sediment flux. Hence, reach-based sediment transport rate estimates can be derived from unit bar data alone. Moreover, it is shown that reasonable estimates of sediment transport rate can be made using just unit bar migration rates as measured from 2D imagery, including from satellite images, so long as informed assumptions are made regarding average bar shape and height. With recent availability of frequent, repeat satellite imagery, and the ease of undertaking repeat MAV and UAV surveys, for the first time, it may be possible to provide global estimates of bedload sediment flux for large or inaccessible low-turbidity rivers that currently have sparse information on bedload sediment transport rates.

Original languageEnglish
Pages (from-to)953-972
Number of pages20
JournalEarth Surface Processes and Landforms
Volume44
Issue number4
Early online date3 Dec 2018
DOIs
Publication statusPublished - 30 Mar 2019
Externally publishedYes

Fingerprint

airborne sensing
braided river
bedform
bedload
quantification
satellite imagery
river
migration
sediment
sediment transport
dune
imagery
turbidity
equivalence
unmanned vehicle
best practice
rate
Canada
water
image processing

Bibliographical note

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Keywords

  • bedforms
  • bedload transport
  • CubeSat
  • digital surface model
  • drone
  • sandy braided rivers
  • South Saskatchewan
  • UAV

ASJC Scopus subject areas

  • Geography, Planning and Development
  • Earth-Surface Processes
  • Earth and Planetary Sciences (miscellaneous)

Cite this

Quantification of bedform dynamics and bedload sediment flux in sandy braided rivers from airborne and satellite imagery. / Strick, Robert J.P.; Ashworth, Philip J.; Sambrook Smith, Gregory H.; Nicholas, Andrew P.; Best, James L.; Lane, Stuart N.; Parsons, Daniel R.; Simpson, Christopher J.; Unsworth, Christopher A.; Dale, Jonathan.

In: Earth Surface Processes and Landforms, Vol. 44, No. 4, 30.03.2019, p. 953-972.

Research output: Contribution to journalArticle

Strick, RJP, Ashworth, PJ, Sambrook Smith, GH, Nicholas, AP, Best, JL, Lane, SN, Parsons, DR, Simpson, CJ, Unsworth, CA & Dale, J 2019, 'Quantification of bedform dynamics and bedload sediment flux in sandy braided rivers from airborne and satellite imagery' Earth Surface Processes and Landforms, vol. 44, no. 4, pp. 953-972. https://doi.org/10.1002/esp.4558
Strick, Robert J.P. ; Ashworth, Philip J. ; Sambrook Smith, Gregory H. ; Nicholas, Andrew P. ; Best, James L. ; Lane, Stuart N. ; Parsons, Daniel R. ; Simpson, Christopher J. ; Unsworth, Christopher A. ; Dale, Jonathan. / Quantification of bedform dynamics and bedload sediment flux in sandy braided rivers from airborne and satellite imagery. In: Earth Surface Processes and Landforms. 2019 ; Vol. 44, No. 4. pp. 953-972.
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