Mainstem flow

Mainstem flow and sediment

Tributary flow and sediment

Sediment budget reach

RM 0-30 – upper Marble Canyon

RM 30-61 – lower Marble Canyon

RM 61-87 – eastern Grand Canyon

RM 87-166 – central Grand Canyon

RM 166-225 – western Grand Canyon

Between July 1 and November 17, 2012, ...

Between 551,000 

and 782,000 metric 

tons accumulated 

in upper Marble 

Canyon

91,000 – 101,000 metric 

tons were transported 

past the RM 30 gage

617,000 – 769,000 metric tons entered 

Colorado River from the Paria River

Little to no fine 

sediment 

accumulated in 

lower Marble 

Canyon

Mass balance prior to 2004 and 2008 HFEs

July 1 to November 2004: 275,000 – 491,000 metric tons

December 2004 – March 2008: 567,000 – 1,823,000 metric tons

2. HFER Protocol 

implementation
Cumulative sand 

delivery to the 

Colorado River

617,000

769,000

Paria River at Lees Ferry

water
91,000

101,000

Cumulative amount of sand transported out 

of upper Marble Canyon (past RM30 gage)

water

Cumulative amount of sand 

available for transport in upper 

Marble Canyon

551,000

782,000
water

Sand transport past 

RM30

Sand mass 

balance in upper 

Marble Canyon

212,000

477,000
2012 Controlled Flood

0

10,000

20,000

30,000

40,000

50,000

-10 -5 0 5 10 15 20

1996

2004

2008

2012

DISCHARGE, IN CUBIC FEET PER SECOND

TIME, IN DAYS RELATIVE TO DEPARTURE FROM NORMAL DAM OPERATIONS

• 24 hr. upramp from 7,000 to 43,400 ft3/s

• 24 hr. peak at 43,400 ft3/s

• 53 hr. downramp from 43,400 to 31,200 ft3/s

• 24 hr. downramp from 31,200 to 7,000 ft3/s
Deposition rates of sand in eddies 

are primarily determined by the 

concentration of sand transported by 

the river. Concentrations change with 

time. 
Suspended-Sand Concentration on Day 

One of Flood

(after Topping and others, USGS OFR 2010-1128, 2010) 
Bed-sand median 

grain size

Bed-sand area 

(amount)
Suspended-sand median grain size

(after Topping and others, USGS OFR 2010-1128, 2010) 
Sand-concentration ranking of 

controlled floods 

RM 0 RM 30 RM 61 RM 87 RM 166 RM 225

2008 2008 2008 1996 ≈ 2008 2008 2012

2004 2004 2004 ≈ 2012 2012 ≈ 2004 1996 2008

1996 2012 1996 2012 2004

•75% of sand-concentration rankings agree with bed-sand area (amount) analysis

•Only 40% of sand-concentration rankings agree with bed-sand grain-size analysis

•Mass-balance sand budgets should teach us more...
Sand mass-balance context

Period of budget Upper Marble Canyon Lower Marble Canyon

July 2002 -

pre2004 flood

330,000 ± 194,000 -280,000 ± 110,000

pre2004 flood –

pre2008 flood

900,000 ± 640,000 290,000 ± 350,000

pre2008 flood –

pre2012 flood

-1,500,000 ± 620,000

(mostly during MayAugust 2011)

-12,000 ± 430,000

July 2012 –

pre2012 flood

670,000 ± 120,000 18,000 ± 15,000

during 2012 flood -320,000 ± 13,000 -78,000 ± 36,000

Shown are changes in sand mass (metric tons)
Relations between sand mass balance

and sand concentrations during 

controlled floods

Upper Marble Canyon Lower Marble Canyon

Cumulative

post-July 2002

sand mass

before flood

(metric tons)

% of sand

concentration

during 2004 

flood

Cumulative

post-July 2002

sand mass

(metric tons)

% of sand

concentration

during 2004 

flood

2004 flood 330,000 100% -280,000 100%

2008 flood 1,230,000 140% 10,000 140%

2012 flood -270,000 68% -2,000 95%

post 2012 flood -590,000 -80,000
flow bed sand area

•Spatial decrease in “flow” leads to deposition

•Spatial increase in bed-sand grain size leads to deposition

•Spatial decrease in bed-sand area (amount) leads to deposition

•Greatest deposition rates occur in eddies when greatest flow 

“deceleration” occurs between channel and eddy, and sand in 

upstream channel is as fine as possible and amount on upstream 

channel bed is relatively large

bed sand 

area
RM 2.5 L

11/18/2012 0 11/24/2012 1

RM 8 L

11/18/2012 0 11/24/2012 1

Substantial Gain (18 sites)
RM 9 L

11/18/2012 0 11/24/2012 1

RM 16 L

11/18/2012 0 11/24/2012 1
Grand Canyon River Guides 

Adopt-a-Beach Site

Shinumo

Wash Camp

Apr 2008 RM 29.4 L

Oct 2010 Dec 2012
RM 41 R

11/18/2012 0 11/27/2012 0

11/18/2012 0 11/28/2012 0

RM 43 L

No Substantial Change(12 sites)
Substantial Loss (3 sites)

11/17/2012 0 11/28/2012

RM 51 L

-1
Sandbar Response to 2012 HFE based on 

Analysis of Images from Remote Cameras

• Summary of evaluations at 33 sites for 2012 HFE 

response

– Substantial Gain (deposition): 18 sandbars (55% of sites)

– No substantial change: 12 sandbars (36% of sites)

– Substantial Loss (erosion): 3 sandbars (9% of sites)

• Downstream trends

– All sites between RM 0 and RM 32 increased

– Downstream from RM 32, split between sites of 

noticeable gain and no change, with a few showing 

noticeable loss
Comparison of Response Among 4 Controlled 

Floods: 1996, 2004, 2008, 2012

• 15 sites with cameras present during all 4 events

– In each year, a few sites did better, a few not as well, 

nothing stands out, too few sites to make any general 

conclusions

• 26 sites with cameras present in 2008 and 2012

– Sandbar larger in 2012: 4 sites, 3 above RM 32

– Sandbar smaller in 2012: 7 sites

– Sandbar about the same in 2012: 15 sites
Sandbars in Marble Canyon before 2012 

Controlled Flood

• Some increase between October 2011 and October 2012

• Both 2011 and 2012 are low relative to early 1990’s and post-flood surveys
0

10,000

20,000

30,000

40,000

50,000

-10 -5 0 5 10 15 20

1996

2004

2008

2012

DISCHARGE, IN CUBIC FEET PER SECOND

TIME, IN DAYS RELATIVE TO DEPARTURE FROM NORMAL DAM OPERATIONS

What is the effect of changing the hydrograph 

of the high flow?
Sandbar Shape – RM 30

• Slope from bar crest to 8,000 cfs level less steep than other floods

• For 3 sites with post-flood surveys and large reattachment bars, the area of newly 

deposited bar above the 8,000 cfs stage with slope less than 8 deg. was larger in 

2012 than previous floods
Conclusions

• 2012 flood resulted in sandbar building, as 

observed in previous controlled floods

• Bar building not as widespread as 2008

– But likely stronger than 2008 in upper Marble Canyon

• Effect of slower rate of flood recession

– Not a dramatically different response

– May have resulted in bars that are less steep in a few 

locations

– Need more observations, numerical modeling, and 

probably controlled laboratory experiments to better 

understand the effect of hydrograph shape
0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

M

e

dia

n

Volu

m

e

R

elative to

Fe

bru

ary 19

9

6

Volu

m

e (m3)

Year

0

10,000

20,000

30,000

40,000

50,000

M

e

a

n

D

aily

Dis

c

h

arg

e

fro

m

Gle

n

C

a

n

yo

n

D

a

m(ft

3/s)

1996 1998 2000 2002 2004 2006

1996 HFE

2004 HFE

2008 HFE

1990 1992 1994 2008 2010

2000

LSSF

Long-term average size of sand deposits along the channel margin depends on 

how much deposition occurs during each flood, how much erosion occurs 

between each flood, and how frequently the floods occur
These are all hypothetical trajectories of long-term sand bar change. 

We are hoping for the best, which can be accomplished by any 

scenario where the aggregate amount to sand deposited by floods 

exceeds the aggregate amount of erosion that occurs in the 

intervening times.