Observations of sand dune migration on the 

Colorado River in Grand Canyon using highresolution multibeam bathymetry

Daniel Buscombe1, Matt Kaplinski2, Thomas Ashley3, Paul E. Grams1, 

Brandon McElroy3, Robert Tusso1

1 U.S. Geological Survey, Grand Canyon Monitoring and Research Center, Flagstaff, AZ 86001

2 School of Earth Sciences and Environmental Sustainability, Northern Arizona University, Flagstaff, AZ 86011 matt.Kaplinski@nau.edu

3 University of Wyoming, Laramie, WY.

Funded by Glen Canyon Dam Adaptive Management Program, USGS Grand Canyon Monitoring and Research Center
Continuous 

monitoring of

suspended sediment 

concentration, grain 

size, and flux

BACKGROUND
Total sediment flux = suspended flux + bedload flux

Bedload

expressed

as a

constant 

proportion

of

suspended

load

BACKGROUND
Rubin et al, 2001

Based on measurements of 

bedform migration made at one 

discharge (595 m3/s) using 

rotating side-scan sonar (Rubin 

et al, 2001)

BACKGROUND
Over the past 15 years, GCMRC scientists have developed a suite of technologies 

that enable us to:

• Rapidly produce 3D maps large areas of the bed using multibeam bathymetry

• Simultaneously map bed sediments using multibeam sonar backscatter

• Measure sand grain size distribution using images acquired with a specialist underwater 

microscope

• Continuously measure of suspended sand concentration and grain size with increasing 

sophistication and accuracy

• Accuracy measure flow velocities using acoustic Doppler profilers

A NEW APPROACH
Water Discharge (m^3/s)

Sediment Flux (kg/s)

Can we develop 

relationships 

between 

measured 

discharge, 

suspended 

sediment flux, 

and bedload flux 

...

... that better 

predict bedload

flux?

Objective: bedload flux as a function of routinely measured quantities

DATA COLLECTION

Bathymetry - Multibeam Sonar (Reson 7125, IxSea hydrins IMU &Heading, Trimble SPS930)

Current Velocity - ADCP (RDI workhorse)

Bed Grain Size - Underwater Camera (Buscombe et al., 2013)

Suspended Sediment – Acoustics samples @ 15 minute intervals, calibrated with D96 & P61 

 point samples from cableway
0

5000

10000

15000

20000

25000

0

200

400

600

800

1000

1200

Discharge(ft3/s)

Suspended Sand Concentration(mg/L)

Feb Mar Apr May Jun Jul

2015

DATA COLLECTION
10000

10500

11000

11500

12000

12500

13000

13500

14000

14500

Discharge (ft3/s)

Time

2/28 3/1 3/2 3/3 3/4 3/5

16,000

17,000

18,000

19,000

20,000

21,000

22,000

7/11 7/12

Multibeam

Surveys

ADCP

Surveys Grain-Size

Surveys

Suspended

Sediment

Samples

DATA COLLECTION

FEB/MAR JULY


MULTIBEAM TRACKLINES
DATA COLLECTION
July 12, 2015 survey

20 survey lines

0.10 m cell size

20-30 soundings/cell

30-60 degrees beam angles 

Mean cell standard deviation = 0.015m

Cell Count = 119

MULTIBEAM UNCERTAINTY
MARCH 4, 2015

Dune height: 30 and 50 cm

Dune length: 5 m 

Migration rate: ~1 m / hour

Fully capture dune 

migration 

using data collected at 

unprecedented temporal 

and spatial resolutions
JULY 12, 2015

Dune height: 75 and 130 cm

Dune length: 10-15 m 

Migration rate: ~2 -5 m / hour

BEDLOAD CALCULATIONS

Universally Applied Bedload 

Coefficient

Bedload flux calculations:

Translation only

1D only

Averaged over field of dunes 

(not calculated per dune) 

Simons et al (1965) - mean 

sediment flux per unit bedform

length

q0 is a constant of integration 

(here set to 0 but a topic of 

research)
BEDLOAD CALCULATIONS

Universally Applied Bedload 

Coefficient
ADCP TRANSECTS
12800 cfs

13000 cfs

13300 cfs

13700 cfs

10800 cfs

10700 cfs

13200 cfs

12100 cfs

streamwise backscatter ADCP SURVEYS
‘FLYING EYEBALL’ BED SEDIMENT

CAMERA
BED SEDIMENT

MEAN GRAIN SIZE 

WAS SLIGHTLY

COARSER IN JULY
BUT LITTLE EVIDENCE

OF GRAVEL IN TROUGHS

Acoustic backscatter sediment 

classification (Buscombe et al 

2014)

Yellow = sand

Hillshaded bathymetry
SUMMARY (SO FAR)

• Dune dimensions (height and wavelengths) scale with discharge

• Dune translation speed increased with higher discharge

• Preliminary results would suggest that bedload is 10-15% of suspended load at discharges of 11-13,000 

cfs (higher than currently implemented in flux-based sediment budget)

• and bedload is around 5% of suspended load at discharges of 17 – 21,000 cfs (in line with previous 

measurements and current predictions)

• However, these are likely to be conservative estimates given a possible contribution of ‘deformation 

flux’ (ongoing work)

• Bedforms are very ‘3 dimensional’, especially at larger discharges

• Bedload would appear to have a weak – moderate correlation with discharge
ONGOING AND FUTURE WORK

• Conduct mapping work at Diamond creek during the next HFE

• Start mapping work at other gage sites (starting at 30-mile gage in May 2016)

• Account for flux contribution (if any) of dunes changing shape as they migrate (Tom Ashley’s Masters 

thesis)

• As we acquire more data, develop and test relationships for bedload as a function of flow (velocity / 

discharge), grain size and suspended sediment

• Testing ways to autonomously and continuously monitor bedload

?

?
Thank You