Changes in sandbars and campsites during the 

HFE Protocol

GCDAMP Annual Reporting Meeting

January 13, 2020

Joe Hazel and Matt Kaplinski

Northern Arizona University

Paul Grams and Robert Tusso

U.S. Geological Survey

Grand Canyon Monitoring and Research Center
Overview

• Background on the HFE Protocol

• Background on study sites, methods, and database

• Observations of sandbar response from HFE protocol

• Observations of sandbar response to 1990-2019

• Campsite area response during the HFE protocol

• Summary
HFE-related Science and Management Questions:

HFE-related Science and 

Management Questions:

• With frequent HFEs, will 

sandbars increase in size 

and abundance?

• Will frequent HFEs cause 

sand supply in channel to 

decrease and exacerbate 

sediment deficit?

Pre-dam: 

• Annual floods

• Abundant sand 

supply

• Large sandbars

Post-dam I: 

• Daily small floods

• Limited sand supply

• Eroding sandbars

• Unplanned floods (spills)

Post-dam II:

• Restricted hydropower 

operations

• High Flow Experiments 

(HFEs) 

• triggered by sand 

supply from Paria River

Pre-dam Post-dam I

Pre-HFE Post-HFE

https://waterdata.usgs.gov
The HFE Protocol: 

• Track sand inputs from Paria River 

and model sand budget during 

designated accounting periods

• July 1 – Dec. 1

• Dec. 1 – Jun. 30

• Find the magnitude and duration 

of HFE that “fits” the amount of 

sand available

• Schedule HFE

Wright and Kennedy (2011)
Post-dam Floods and High-flows: 

Summary of findings up to start of 2012 HFE Protocol

• Sediment depleted floods scour the bed.

• Sediment-depleted floods can build highelevation sandbars at expense of erosion from 

the channel and low-elevation parts of eddies.

• Floods during sediment-enriched conditions 

build bars without “mining” background sand 

storage.

• High flows should be timed to best take 

advantage of recent tributary sand inputs.

 These findings are basis of the key components of HFE Protocol:

• Tracking sand inputs from Paria River over the summer-fall 

storm season.

• Scheduling HFEs to follow the series of inputs when sand 

storage in Upper Marble Canyon is greatest.

• Scaling the size (magnitude and duration) of HFE to 

“match” the amount of sand accumulation.

Schmidt and Grams (2011); Wright and Kennedy (2011)
Long-term monitoring (LTM) sites between Lees Ferry 

and Diamond Creek

• 32 sites established in 1990 by 

Beus and others (1992)

• Additional sites added in 1993, 

1996, 2002, and 2008 for a 

total of 44 sites

• The percentage of eddies with 

monitored sandbars is 9% and 

7% in Marble and Grand 

Canyons, respectively

• 37 sites are monitored for 

campsite area
Sandbar and campsite survey methods

*Campsite Area = a smooth substrate (preferably sand) with no 

more than eight degrees of slope with little or no vegetation

Total Station Surveys of Sandbar Topography, 

Campsite Area* (vegetation survey plots), 

and Daily Imagery
Flow regimes, high-flow experiments, and sandbar surveys

Hazel and others, in prep

• 11 HFEs between 1996 and November 2018, including lower magnitude HMFs in 

1997 and 2000

• ~1,750 surveys collected between 1990 and 2019

• The original LTM sites have as many as 50 repeat surveys

• Sandbar surveys during the HFE protocol are made ~11 months following each HFE 

1990 1995 2000 2005 2010 2015 2020

0

1,000

2,000

Discharge, in cubic meters per second

1990-91

experimental

flows

1996

HFE

1997

Test Flow

2000 LSSF

HMF Flows

2004

HFE

2008

HFE

2012

HFE

Modified Low Fluctuating Flow

(MLFF) Alternative

Interim

Operating Critera

2013

HFE

2014

HFE

2011

Equalization

Flows

2011-2020 Multi-Year

HFE Protocol

2016

HFE

2018

HFE
Sandbar database and web application

• In development since 2014

– Started as a javascript app supported by oracle 

database

– Now mainly in python and supported by a sql

database (free and open source)

• Includes a desktop “workbench” for 

loading, processing and viewing data

• Web application for public access to data

• Series of python scripts for generating 

summary plots

• Next step is to incorporate those in workbench 

and web application

Desktop sandbar 

workbench

Sandbar web 

application

www.gcmrc.gov/sandbar OR www.usgs.gov/apps/sandbar
What are the high-flow 

experiments (HFEs) doing?

Debris Fan

HFEs transfer sand from channel and lowelevation parts of eddies to sandbars 

along channel margins

Eroded sandbar before HFE

HFE inundates sandbar

Sandbar following HFE

https://waterdata.usgs.gov
November 2018 High-flow Experiment Deposition-1

09/28/2018 12/04/2018

HFE Deposition 

HFE Deposition 

River Mile (RM) 122R

11/01/2018 11/11/2018

River Mile (RM) 029R
November 2016 High-flow Experiment Sandbar Deposition-2

River Mile (RM) 23L

HFE Deposition filling gullies

11/06/2016

11/13/2016
Rebuilding of sandbars and 

campsites affected by 

tributary floods

• Flash flood and debris flow at 220-

mile in 2018 eroded and wiped out 

middle camp (a long-term monitoring 

site)

• Also eroded gully through upper 

camp

• Both partially rebuilt by 2018 HFE

Middle camp

upper camp

11/3/2018

11/13/2018

RM 220 R
Cumulative increases in sand 

volume at some sites

Post-HFE 2018

pre-HFE 2012

2012 HFE

Fall 2012 to Fall 2018 increase

Preliminary results, subject to review, do not cite

RM 9 L
Two analysis periods between 1990 and 2019

• Sand depleted period (1990-

2003)

– Median discharge ~351 m3/s

– Sand conveyance threshold exceeded 

78% of the time

– Paria sand supply was average or 

above average in only 5 years during 

the 14-year period

• Sand enriched period (2004-

present)

– Median discharge ~332 m3/s

– Sand conveyance threshold exceeded 

80% of the time

– Paria sand supply was average or 

above average in 9 years during the 

15-year period

– 7 HFEs were timed to occur before 

inputs were conveyed through the 

system

– The difference? Large inputs and only 

one year with high releases

1990 1995 2000 2005 2010 2015

0

250

500

750

Annual mean discharge, in cubic meters per second

A

1990 1995 2000 2005 2010 2015

Calendar year

0

1,000

2,000

3,000

Sand supply, in thousand metric tons

Sand Depleted Period Sand Enriched Period

Sand Depleted Period Sand Enriched Period

Long-term annual

average sand input

(1924-2016)

B

Sand conveyance

or erosion threshold

Hazel and others, in prep
Photographic analyses of the HFE protocol

Results of 2018 HFE on par with previous HFEs

11/1/2018

11/10/2018

www.gcmrc.gov/sandbar Preliminary results, subject to review, do not cite

10/11/2019
Sandbar size during the HFE protocol period

• Positive trends in most bar types and in both Marble and Grand 

Canyon

• Increases in sandbar volume off-set sandbar erosion that 

occurred between HFEs

Wide, vegetated bars

Narrow to medium 

reattachment bars

Undifferentiated and 

separation bars

Preliminary results, subject to review, do not cite
Long-term sandbar response size during the HFE protocol period

• Increased HFE frequency is 

maintaining sandbars at a 

majority of the sites

• HFE protocol is off-setting erosion 

characteristic of the 1990-2003 

sand depleted period for most bar 

types

• Trends for separation and 

undifferentiated eddy bars show a 

slight decline in Grand Canyon

• Trends are markedly similar for 

both Marble and Grand Canyons

Preliminary results, subject to review, do not cite
Campsite area in Marble and Grand Canyons

• HFEs increase and maintain 

campsite area

• Decreases are primarily due to 

vegetation expansion

• Campsite area declines in years 

without HFEs

• Trends are similar for both 

Marble and Grand Canyons

RM 194 L

4/20/1996 11/20/2016
Summary

• Each HFE since 2012 has resulted in 

sandbar deposition

• Increases in sandbar size occur at 50% or 

more of monitoring sites

• There is no difference in site response in 

different parts of the canyon

– Marble and Grand Canyon show similar trends

• Although bars erode, they are larger than 

they would be without HFEs

• HFEs do not scour or remove vegetation

– Erosion and vegetation encroachment decrease 

campsite area during the intervening periods 

between HFEs

• There is evidence for cumulative increases 

in bar size at some sites whereas others 

continue to decrease

• The majority of sandbars are those that 

reliably aggrade during HFEs

RM 9 L

Post-HFE 2018

pre-HFE 2012
Acknowledgements

Erich Mueller, Daniel Buscombe, 

Thomas Gushue, Daniel Hamill, 

James Hensleigh, Robert Ross, 

Keith Kohl, Jack Schmidt, Laura 

Kennedy, David Topping, Rod 

Parnell, Bryan Cooperrider, Karen 

Koestner, Emily Thompson, Daniel 

Hadley, Katie Chapman ... 

In Memoriam: Greg Sponenburgh

and Frank Protiva