Project 2:

Streamflow, 

Water Quality, 

Sediment Transport, 

and Sand Budgets 

in the Colorado 

River Ecosystem
Project Overview

We collect, post, and analyze the following data at 

stations located through the Colorado River Ecosystem, 

including key tributaries...

• Stage

• Discharge

• Water temperature

• Salinity (specific conductance)

• Turbidity

• Dissolved Oxygen

• Suspended- and bed-sediment data

• Sediment loads (silt and clay loads and sand loads)

• User-interactive sand budgets in 6 reaches from Lees Ferry to Lake Mead

• User-interactive duration-curve tool for any continuous parameter

All other GCDAMP-funded projects use these data, and 

data from this project inform LTEMP

Citation for data and plots on most slides:

U.S. Geological Survey, 2018, Discharge, sediment, and water quality monitoring, 

Grand Canyon Monitoring and Research Center: accessed on 

January 14, 2018, at http://www.gcmrc.gov/discharge_qw_sediment/.
The USGS team

• David Topping, GCMRC

• Ron Griffiths, GCMRC

• Dave Dean, GCMRC

• Nick Voichick, GCMRC

• Tom Sabol, GCMRC

• Nancy Hornewer, AZ Water Science Center

• Joel Unema, AZ Water Science Center

• Megan Hines, Office of Water Information

• Brad Garner, Office of Water Information
Work completed under 2015-2017 TWP to address the 

following fundamental science question...

How do operations at Glen Canyon Dam affect flows, 

water quality, sediment transport, and sediment 

resources in the Colorado River Ecosystem? 

• All required monitoring data collected, processed, and posted to the web, 

including those data used to design and evaluate the Nov. 2014 and 2016 

HFEs

• Substantial improvements to the project website at 

https://www.gcmrc.gov/discharge_qw_sediment/, including the release of 

user-interactive duration-curve plotting tool

• 10 peer-reviewed interpretive papers published (see list in Annual Report)

• 1 additional peer-reviewed journal article accepted for publication and 

four others in various stages of prep. and/or journal review
Key drivers of 

sand transport 

and storage in 

the Colorado 

River Ecosystem 
Sand concentration can be “regulated” by changes in 

flow and changes in bed-sand grain size 

(Rubin and Topping, WRR, 2001)

Increase in flow (discharge) 

with constant bed-sand 

grain size leads to increase in 

sand concentration

Increase in bed-sand grain size 

under constant discharge 

leads to decrease in sand 

concentration

Rubin and Topping (2001) plots of data from flume experiments of Guy et al. (1966)
-analyses indicate that although changes in discharge generally 

regulate sand concentration, changes in bed-sand grain size play 

an important and sometimes dominant role in regulating 

suspended-sand concentration throughout the Colorado River in 

the CRE, including upstream from the Paria River at Lees Ferry 

Lees Ferry gage (RM 0) Grand Canyon gage (RM 87)

Data from USGS (2018)
1. Median size of tributary sand supply is finer than 

antecedent bed-sand grain size in Colorado River

Why is this the case?

• Flux-weighted mean D50 of Paria

River sand supply was 0.133 mm 

among 3,256 physical suspendedsediment samples collected from 

1996 through 2017

• Mean D50 of bed sand at RM30 was 

0.336 mm among 85 crosssectionally averaged measurements 

made from 1998 through 2017 

• Minimum D50 of bed sand at RM30 

was 0.165 mm and maximum D50 of 

bed sand at RM30 was 0.435 mm 

among these measurements

Data from USGS (2018)
• Long periods of time between tributary floods for bed to be winnowed

• Over last ~5 years, Paria River sand supply has been above average and the 

LCR sand supply has been below average

• Large sand-supplying floods in Paria River and LCR are poorly correlated

• Measurements indicate Paria River and LCR are only large suppliers of sand

2. Tributary sand supply is highly episodic, with long periods of 

tributary quiescence when the discharge of the Colorado River 

is relatively high

Data from USGS (2018)
• Almost all large Paria River floods occur during August through October

• Only two large Paria River floods have occurred in the winter during the 

last 20 years (January 2005 and December 2010)

• Thus, spring HFEs may only rarely occur because the HFE trigger in the 

LTEMP is reset on December 1

Data from USGS (2018)
• Lagged covariance analysis of 6-hour Paria River sand loads and Colorado River bedsand grain size indicates that large Paria River floods generate sand waves with 

leading edges that migrate throughout the CRE within ~5 days

• The sand waves generated during these floods cause fining of the Colorado River 

bed sand that persists for ~170 days after these floods in upper Marble Canyon, and 

over ~250 days in lower Marble Canyon and eastern Grand Canyon

Analysis after Rubin and Topping (2001, 2008) and USGS (2018)
Downstream migration of sand waves leads to bed-sand grain size that is 

inversely correlated with sand storage and bed-sand area that is positively 

correlated with sand storage (FINER BED = MORE SAND IN STORAGE)

Analysis after Rubin and Topping (2001, 2008), Topping et al. (2010), and USGS (2018)

Nondimensional RM30 bedsand grain size and Upper 

Marble Canyon sand budget

Nondimensional RM30 bedsand area and Upper Marble 

Canyon sand budget
Colorado River near Grand Canyon, AZ, 09402500

Movie courtesy of David M. Rubin

As sand storage increases...the bed-sand fines...leading to increased 

suspended-sand concentrations and increased sand export, 

thus self-limiting the amount of sand in storage
Monthly upper Marble Canyon sand budget is typically negative unless 

Paria River monthly sand load exceed 100,000 metric tons

Analysis after Rubin and Topping (2001, 2008) and USGS (2018)

RM30 monthly mean discharge and bed-sand grain size 

7,060-10,600 cfs, FINE BED 

7,060-10,600 cfs, COARSE BED 

10,600-14,100 cfs, FINE BED 

10,600-14,100 cfs, COARSE BED 

14,100-17,700 cfs, FINE BED 

14,100-17,700 cfs, COARSE BED 

e 17,700-21,200 cfs, FINE BED 

0 17,700-21,200 cfs, COARSE BED 

e 21,200-24,700 cfs, FINE BED 

'-' 21,200-24,700 cfs, COARSE BED 

e Months with HFEs, FINE BED 

Months with HFEs, COARSE BED 

2 , 0 00, 000 .---......-T""""'lr-T""T"T"r~.........-r-""T""T""T'"~---.--T"""T""T""T"T'TTT""----,-"""T"""T"""l'""T"T'TT'1.-----, 

-CJ) 

C 

0 

-

u 1,500,000 "-

-Q) 

E 

-

~ 1,000,000 

rn 

E 

"O 

@ 500,000 

CJ) 

C 

~ 01-----r-.Fr-+:c~ -rr-~ ~ =-~ ~ ~~---~ C 

rn 

.c 

u 

~ -500,000 

-C 

0 • 

• • 

I ~ 

-1,000,000 ~~~~~~~~~~~~~~ 

100 1,000 10,000 100,000 1,000,000 

Monthly sand supply (metric tons) 
For cases where the Paria River month sand load <100,000 metric tons, 

monthly upper Marble Canyon sand budget tends to be “less negative” 

when bed-sand grain size is relatively coarse (and amount of sand in storage 

is small)

When monthly mean bed-sand grain size

is finer than the 10-year median value...

When monthly mean bed-sand grain size

is coarser than the 10-year median value...

Analysis after Rubin and Topping (2001, 2008) and USGS (2018)
• Monthly lower Marble Canyon sand budget tends to be negative, including 

during HFEs, when monthly mean discharge exceeds ~14,100 cfs and 

bed sand is fine (and amount of sand in storage is large)

• Monthly lower Marble Canyon sand budget tends to be positive, including 

during HFEs, when monthly mean discharge is less than ~21,200 cfs and 

bed sand is coarse (and amount of sand in storage is small)

Analysis after Rubin and Topping (2001, 2008) and USGS (2018)
When monthly mean bed-sand grain size

is finer than the 10-year median value...

When monthly mean bed-sand grain size

is coarser than the 10-year median value...

Analysis after Rubin and Topping (2001, 2008) and USGS (2018)

Although the monthly lower Marble Canyon sand budget remains positive 

under much higher discharges when bed-sand is coarse (and amount of 

sand in storage is small), it is only generally positive when monthly mean 

discharge < 10,600 cfs
Even though pre-dam sand storage was also grain-size-limited, 

seasonal sand storage capacity was much larger because discharges < 

7,980 cfs occurred half of the time

Topping et al. (WRR, 2000a) Topping et al. (USGS-PP, 2003)

Pre-dam transition from sand accumulation to conveyance occurred above ~9,000 cfs

7,980 cfs
Grand Canyon Monitoring and Research Center 

I About GCMAC 11 Science ActMtlea 11 Library and Publicallona 11 Mapa 1111d Data Por1al 11 Education 11 MeeUnp and EMnta I 

Grand Canyon Reaches 

Home > C>sc"!arge. Sed ment anc Water Oua.ty > Grand Canyon Reaches 

5 1 G IQ 

r,i~ 'Can r,~ l"'.oceo h.,INH Ci 

- - - 11~"i•1> - - l"d l 1 

Ro!laNilllDIJ 

cOCON1l,O 

"1.4 tf , u COCO 1 /iO l' l T[ U 

? 4 

74 .. n ·N ,\lff 

f 

93. 1J1T 1202 r" 

K ib b Enr, S IJJII 

" Fb olaft 

T ba C ity 

E 0 0 E 

Hop, 

Rl,511,.....~llln 

5 E 

0 L I) I 

Reaches 

II 

II 

II 

II 

II 

II 

Upper Marble Canyon 

(Colorado River at Lees Ferry, AZ. to Colorado River 

near river mil'e 30) 

Lower Marble Canyon 

(Colorado River near river mfle 30 to Colorado River 

above Lltt te Colorado River near Desert View, AZ) 

1:astern Grand Canyon 

(Colorado Rlver above Little Colorado River near 

Desert View, AZ. to Colorado Ri,ver near Grand 

Canyon, AZ) 

East Central Grand Canyon 

(Colorado River near Grand Canyon, AZ. to 

Colorado River above National Canyon near Supal , 

AZ) 

West Central Grand Canyon 

(Colorado Rlver above National Canyon near Supal, 

AZ. to Colorado River above Diamond Creek near 

Peach Springs, AZ) 

Western Grand Canyon and the Lake 

Mead Delta 

(Colorado River above Diamond Creek near Peach 

Springs, AZ. 10 Pearce Ferry near river mile 280} 
Upper Marble Canyon

7-1-2016 to 1-1-2018

Plots and values from USGS (2018)
Lower Marble Canyon

7-1-2016 to 1-1-2018

Plots and values from USGS (2018)
Eastern Grand Canyon

7-1-2016 to 1-1-2018

Plots and values from USGS (2018)
East Central Grand Canyon

7-1-2016 to 8-31-2017

Plots and values from USGS (2018)
West Central Grand Canyon

7-1-2016 to 8-31-2017

Plots and values from USGS (2018)
Western Grand Canyon and the Lake Mead Delta

7-1-2016 to 12-16-2017

Plots and values from USGS (2018)
Although sandbars have generally been built 

in each reach during the 2004, 2008, 2012, 

2013, 2014, and 2016 HFEs...

These controlled floods have had 

different systematic effects on the 

sand budget in some reaches as a function 

of the antecedent bed-sand grain size
Conclusions

• Sand storage is grain-size-limited in the post-dam Colorado River under 

the relatively high discharges (i.e., >8,000 cfs) that are always released by 

Glen Canyon Dam 

• Sign of upper Marble Canyon sand budget is typically negative unless Paria

River has had a recent large flood 

• Bed-sand grain-size regulation of sign of monthly sand budget becomes 

more important downstream from upper Marble Canyon

• Spring HFEs will be triggered only rarely because large Paria River floods 

are extremely rare in the winter and early spring

• Annual Marble Canyon sand budgets are negative at annual mean 

discharges >11,300 cfs (8.2 MAF) unless Paria sand inputs exceed 1.1 

million metric tons, then budgets are negative when annual mean 

discharges >13,400 cfs (9.7 MAF) 

• Annual Grand Canyon sand budgets are also negative at annual mean 

discharges >11,300 cfs (8.2 MAF) unless Paria + LCR sand inputs exceed 2 

million metric tons, then budgets remain positive until annual mean 

discharges >14,800 cfs (10.7 MAF)

• It remains unclear whether sand resources are sustainable except during 

periods when Paria River and LCR sand inputs are above average and dam 

releases are relatively low (i.e., <13,400 cfs or 9.7 MAF)
Thank you