Linkages between controlled floods, eddy sa

dynamics, and riparian vegetation along the Colo

in Marble Canyon, Arizona

flow

1984

flow

1984 2013 elevation standa

Erich R. Mueller, Paul E. Grams, Joseph E. Hazel, Jr., Daniel Sarr, and M
Sandbars: Where to monitor?

• Variable histories and trajectories

• No real “average”• 45 sites in 2‐week trip (must be selective)

• Criteria for grouping:

I. Distance from dam

II. Narrow/wideIII. Eddy characteristicsIV. Vegetation?
PIC

• Focus on ~24 sites with

reattachment bars typical

of a fan‐eddy complex

(13 MC/11 GC)

• Annual to sub‐annual bar

surveys; less frequent full

bathymetric surveys

• Most recent pre‐ and

post‐flood bathymetric

surveys from 2008

HERE; or diagram her

Over there, show “fan‐eddy” diagram, then

hydrograph

Reattachment

Bar

ra

boat

Se

Fan-Eddy Complex 
Background 

• The 1980s floods were the largest post‐dam floods, approximately 

controlled floods

• Many long‐term monitoring sites were still relatively free of veget

early 1990s

• Vegetation establishment on bars has varied between sites, influe

flood response

1984

100 m

1984

100 m

2013

“51‐mile”
11/25/2014 3/2/19963/31/19964/7/199610/25/199610/26/1998

“Kwagunt Marsh”

low flow eddy

2014 flood

deposit

A B

1984

200
3/11/20089/2/2008 7/20/2012 3/08/2008 2/10/2008

3/8/20083/11/2008 9/4/2008 7/20/2012 3/4/2008

11/20/2012 11/25/2012

11/25/2012 11/20/2012

Aggradation and vegetation stabiliz

Little vegetation establish

9/23/2015

9/23/2015

FLOW

“Above Lava Chuar”

River Mile 66

“Willie Taylor”

River Mile 45
Vegetation encroachment increases as the 

canyon widens downstream 

(c.f. Sankey et al., 2015)

For large eddies (>10,000 m

reaches are also mor

Lower Marble 

Can the degree of riparian vegetation encroachment serv

to better predict sediment dynamics in individual e
Blue: Controlled F

2008 Flood R

“51‐mile”

more veg 100 m

flow

DEM OF DIFFERENCE

“Willie Taylor”

“Eminence”

less veg

reattachment bar only ab

ControlledFloods

Channel and Eddy below 

Green: Mapped meters of ch

30 meter

V

-7 -6 -5 -4 -3 -2 -1 0 1 
Elevation 

standard 

deviation 

(cm)

Sediment st

changes dom

in eddy

“Kwagunt Marsh”

“51‐mile”

1‐2020‐3535‐5050‐7070‐9090‐110110‐130130‐160160‐200200‐260

“30‐mile”

Sediment storage

changes dominantly

in channel

Negative Q-V relation Positive Q-V 

More Narrowing/Veg Less Narrowin
Total site sedimen

change with disc

(slope of the “Q‐V 

shows a clear correl

the degree of veg

encroachme

Post‐2012 Flood

Negative Q-V relation Posit

ሺ൅ሻሺെሻ
   

‐   

Controlled ...but theseflood dataresponse are only linked for thewith 1996, propo

200

eddy vegetated 2008 controlled and slope floods. of Q‐V relatio

Larger post‐flood sandbars

Post‐20142 Flood

ሺെሻ 
Linkage to hydraulics: Large Eddy Simulation (LES

Kwagunt Marsh: Em

Willie Taylor: 51‐Mile: Veg’d/Narrowed Part

Surface Ve

Veg’d Un‐Veg’d

Hypothesis 1: Vegetation mirrors hydraulic field  low energy = more vegeta

Hypothesis 2: Vegetation is changing hydraulic field  more vegetation = shr
51‐Mile:

Veg’d

Kwagunt Marsh:

Veg’d/Narrowed

LES MODELING ED

9/7/2008

6/6/2008

4/6/20083/12/2008

Rapid Post-Flood Erosion 

“Willie Taylor” RM 45

TOTAL 
Conclusions

• The degree of bar stabilization/channel narrowing by 

is indicative of eddy‐channel sediment storage dynam

flow hydraulics

• Bars with limited vegetation establishment tend to be 

energy settings and often erode more rapidly followin

• Observations of vegetation change may thus allow for 

understanding of spatial variability in bar response

• Ultimately, sandbar variability coupled to sediment su

hydraulics shaped by the channel boundary

Acknowledgements This work was supported by the Glen Canyon Adaptive Management Program. Many scientists, field technicians, and boat operators assisted in data collection during decades of monitoring, including Matt Kaplinski, Jack Schmidt, Rob Ross, Bob Tusso, Tom Gushue, Barbara Ralston, Emily Palmquist, and many more.