U.S. Department of the Interior

U.S. Geological Survey

Fluvial-aeolian sediment connectivity during 

the current HFE protocol: 

effects for dunefields and archaeological sites

Joel B. Sankey, USGS GCMRC

Alan Kasprak, USGS GCMRC

Joshua Caster, USGS GCMRC

Helen C. Fairley, USGS GCMRC

Amy E. East, USGS PCMSC

Project 4 of the Triennial Workplan

Elements 4.1 and 4.2 (Research and Monitoring)

Glen Canyon Dam Adaptive Management Plan 

Annual Reporting Meeting, January 24th 2017
Landscapes downstream from Glen Canyon Dam 

contain archaeological resources that are affected by 

geomorphic processes

(East et al., 2016)
Sand can potentially help preserve archaeological features by 

direct burial and/or by mitigating gullying and other erosion

(East et al., 2016)
Sand is sourced from the Colorado River,

 And can be deposited on archaeological features or within 

gullies via

 Fluvial (river) deposition

 Aeolian (wind) deposition

 Most archaeological sites are above the highest contemporary 

river stage, so aeolian deposition is the most likely mechanism 

for preservation and/or erosion mitigation 

(East et al., 2016)
Most archaeological sites are situated

above the HFE flood stage throughout

Grand Canyon (East et al., 2016)...

To help preserve sites in place through direct burial and/or erosion mitigation:

- Option 1: Flood and bury sites with large sediment-rich floods

- Option 2: Rely on wind to move sediment from sandbars to sites

Floods (HFEs) deposit sediment

in sandbars up to ~45,000 ft3/s
Most archaeological sites are situated

above the HFE flood stage throughout

Grand Canyon(East et al., 2016)...

To help preserve sites in place through direct burial and/or erosion mitigation:

- Option 1: Flood and bury sites with large sediment rich floods

- Option 2: Rely on wind to move sediment from sandbars to sites

Floods (HFEs) deposit sediment

in sandbars up to ~45,000 ft3/s
The results: Relatively few archeological sites are now ideally situated to 

receive aeolian sand supply from sandbars deposited by recent controlled floods 

(HFEs) from Glen Canyon Dam (decreased from 98 sites in 1973 to 32 in 2012)

“Active” River Channel

East et al., 2016, Conditions and processes affecting sand resources at archeological 

sites in the Colorado River corridor below Glen Canyon Dam, Arizona: U.S. Geological 

Survey Professional Paper 1825, 104 p., http://dx.doi.org/10.3133/pp1825.

The question: Can Colorado River sediment enhance the preservation of rivercorridor archeological resources in these landscapes through aeolian sand 

deposition and mitigation of gully erosion?

The problem: Landscapes downstream from Glen Canyon Dam contain 

archaeological resources that are affected by fluvial (river), aeolian (wind), and 

hillslope (gravity and rainfall-runoff) geomorphic processes.
Landscape Change at Archeological Sites Receiving 

Sand Supply After HFEs (East et al., 2016)
Landscape Change at Archeological Sites Receiving 

Sand Supply After HFEs (East et al., 2016)

Results and conclusions relative to dam operations 

and river management

• Geomorphic change detection spanning the 2012 & 2013 HFEs

• Archaeological monitoring sites were coupled with upwind river 

sand supplies (sandbars)

• Sand loss from erosion generally exceeded aeolian deposition of 

river-derived sand

• Considerations for future work

• River-sourced sand deposition is a time-dependent process, and 

the outer limit of that process may extend for many years after 

any individual HFE

• HFEs with targeted vegetation removal could produce a net 

sediment surplus at some sites

• Need new analysis methods and additional data
Project 4: New Approaches

 Use modelling to demonstrate expected characteristics 

of archaeological sites in dunefields that are resupplied with windblown sand from HFE deposits

 Use geomorphic change detection of lidar survey 

monitoring data to make inferences for individual sites 

and dunefields during the time period of the current 

HFE protocol

 2012, 2013, & 2014 HFEs
Fluvial-aeolian sediment connectivity during the current HFE 

protocol: effects for dunefields and archaeological sites

Wind

River
Modelling dunefield changes as a function of 

sediment supply

Model dunefield change with consistent 

wind direction and upwind sediment source 

area for 3 consecutive “HFE” time periods

1. No sediment supply

2. Weak sediment supply

3. Strong sediment supply

Wind Direction

Sediment Supply

Source

Dunefield
Erosion

Deposition

DEM0

DEM1

No Supply

DEM2

No Supply

DEM3

No Supply

DoD1 DoD2 DoD3

No 

Sediment

Supply

DEM0

DEM1

Weak Supply

DEM2

Weak Supply

DEM3

Weak Supply

Sum of

3 DoDs

Weak Supply

DoD1 DoD2 DoD3

Weak 

Sediment

Supply

DEM0

DEM1

Strong Supply

DEM2

Strong Supply

DEM3

Strong Supply

Sum of

3 DoDs

Strong Supply

DoD1 DoD2 DoD3

Strong 

Sediment

Supply

Step 

Initial

Step

“1”

Step

“2”

Step

“3”

Modelling dunefield changes as a 

function of sediment supply

(preliminary 

results, please 

don’t cite)

Sum of

3 DoDs

No Supply

(preliminary results, please don’t cite)
Model 

Scenario

Net change in 

sediment volume

No sediment 

supply -

Weak 

sediment 

supply

+

Strong 

sediment 

supply (x101)

++

Wind Direction

Sediment Supply

Source

Erosion

Deposition

Modelling dunefield changes as a function of 

sediment supply

(preliminary results, please don’t cite)
Model 

Scenario

Net change in 

sediment volume

No sediment 

supply -

Weak 

sediment 

supply

+

Strong 

sediment 

supply (x101)

++

Wind Direction

Sediment Supply

Source

Erosion

Deposition

Modelling dunefield changes as a function of 

sediment supply

Does it actually work like this 

in Grand Canyon?

(preliminary results, please don’t cite)
Sites

Glen Canyon: 

• Three sites

• Lidar Surveys

• Pre-2012 HFE

• Pre-2013 HFE

• Post-2014 HFE

Grand Canyon:

• Four sites

• Lidar Surveys

• Pre-2012 HFE

• Pre-2013 HFE

• Pre-2014 HFE

• Post-2014 HFE
Sites

Glen Canyon Sites

• Upstream of the Paria

• Low/No HFE sediment supply

• Sub-optimal sediment 

connectivity

• River terraces w/ minimal 

aeolian dunefield morphology

Grand Canyon Sites

• Downstream of the Paria

• High HFE sediment supply

• Optimal sediment connectivity

• Source-bordering aeolian 

dunefields on terraces, debris 

fans, or colluvial/alluvial hillslopes
Sites

Glen Canyon Sites

• Upstream of the Paria

• Low/No HFE sediment supply

• Sub-optimal sediment 

connectivity

• River terraces w/ minimal 

aeolian dunefield morphology

Grand Canyon Sites

• Downstream of the Paria

• High HFE sediment supply

• Optimal sediment connectivity

• Source-bordering aeolian 

dunefields on terraces, debris 

fans, or colluvial/alluvial hillslopes
Sum of 2

DoDs Spanning

2012, 2013, 

& 2014 HFEs

at 3 Glen 

Canyon Sites

River Wind

Glen 1

River

Wind

Glen 2

River

Wind

Glen 3

Glen 

Canyon 

Sites

(preliminary 

results, please 

don’t cite)
Grand 1 Grand 2

Grand 3

Grand 4

Sum of 3

DoDs Spanning

2012, 2013, 

& 2014 HFEs

at 4 Grand 

Canyon Sites

Grand 

Canyon 

Sites

(preliminary 

results, please 

don’t cite)
Aeolian 

Topographic 

Changes in 2

DoDs Spanning

2012, 2013, 

& 2014 HFEs

at 4 Glen 

Canyon Sites

Glen 1

Glen 2

Glen 3

Glen 

Canyon 

Sites

(preliminary 

results, please 

don’t cite)
Grand 1

Grand 2

Grand 3 Grand 4

Aeolian 

Topographic 

Changes in 3

DoDs Spanning

2012, 2013, 

& 2014 HFEs

at 4 Grand 

Canyon Sites

Grand 

Canyon

Sites

(preliminary 

results, please 

don’t cite)
Site Net change in 

aeolian sediment 

volume

(m3)

Average change 

in aeolian 

sediment depth

(cm)

Difference between 

directions of wind and 

long-axis of 

erosion/deposition

Glen1 - 19.9 - 0.46 25 degrees

Glen2 -13.2 - 0.47 10 degrees

Glen3 + 0.44 + 0.01 19 degrees

Grand1 - 55.1 - 1.42 124 degrees

Grand2 - 2.9 - 0.05 52 degrees

Grand3 + 2.4 + 0.09 120 degrees

Grand4 + 16.3 + 0.57 80 degrees

Results

(preliminary results, please don’t cite)
Site Net change in 

aeolian sediment 

volume

(m3)

Average change 

in aeolian 

sediment depth

(cm)

Difference between 

directions of wind and 

long-axis of 

erosion/deposition

Glen1 - 19.9 - 0.46 25 degrees

Glen2 -13.2 - 0.47 10 degrees

Glen3 + 0.44 + 0.01 19 degrees

Grand1 - 55.1 - 1.42 124 degrees

Grand2 - 2.9 - 0.05 52 degrees

Grand3 + 2.4 + 0.09 120 degrees

Grand4 + 16.3 + 0.57 80 degrees

Results

Glen Canyon sites: 

• spatial patterns of erosion and deposition are not consistent with 

source-bordering aeolian dunefield morphology

• net wind erosion or minimal deposition indicate no sediment supply

Grand Canyon sites: 

• spatial patterns of erosion and deposition are consistent with 

source-bordering aeolian dunefield morphology

• geomorphic changes range from net wind erosion to net wind 

deposition and indicate no to moderate sediment supply

(preliminary results, please don’t cite)
Glen 

Canyon 

Sites

Kasprak, Caster, Bangen, Sankey, in review, 

Glen 1 Glen 2

Glen 3

(preliminary results, please don’t cite)
Grand 

Canyon

Sites

Kasprak, Caster, Bangen, Sankey, in review (preliminary results, please don’t cite)

Grand 1 Grand 2

Grand 3 Grand 4
Results

Site

Proportion of total change in 

sediment volume 2010-2016

Aeolian

Aeolian and Other

(i.e., dynamic)

Other 

(non-aeolian)

(preliminary results, please don’t cite)
Results relative to river management

Site

Proportion of total change in 

sediment volume 2010

-2016

Aeolian

Aeolian and Other

(i.e., dynamic)

Other 

(non-aeolian)

(preliminary results, please don’t cite)
Results relative to river management

Site

Proportion of total change in 

sediment volume 2010

-2016

Aeolian

Aeolian and Other

(i.e., dynamic)

Other 

(non-aeolian) • Sandbar (aeolian sand 

source area) ranged from 

1400-2900 m2 2010-2016

• < 10 % of sandbar covered 

with vegetation (from riparian 

vegetation remote sensing) 

• > 16 m3 of aeolian

deposition from 2010-2016

• equivalent to 2-5 % of 

sandbar volume during 

same time period 

(preliminary results, please don’t cite)
Results relative to river management

Site

Proportion of total change in 

sediment volume 2010

-2016

Aeolian

Aeolian and Other

(i.e., dynamic)

Other 

(non-aeolian) • Sandbars (aeolian source 

areas) are approx. 400 and 

1500 m2, respectively

• Vegetation covers approx. 240 

and 320 m2 of the sandbars

• Management opportunity

• Vegetation removal might 

increase the size of the 

sand source area by 150 

and 25 %, respectively

(preliminary results, please don’t cite)
Results relative to river management

Grand 2

• Removal of riparian 

vegetation might increase 

the size of the sand source 

area by 150 %

(preliminary results, please don’t cite)

Wind

River
Conclusion

 Status and trends of fluvial-aeolian sediment for dunefields and 

archaeological sites

 Long-term (1973-present; East et al., 2016): The number and 

proportion of archaeological sites that are ideally situated to 

receive aeolian sand supply from sandbars deposited by floods 

from Glen Canyon Dam has decreased from 98 in 1973 to 32 as of 

2012

 Project 4 suggests that of the “ideally situated sites”:

 Some have sediment resupply from HFEs

 Some have no sediment resupply from HFEs

 Some are good candidates for experimental vegetation removal 

to enhance sediment resupply from HFEs 

 (and we can identify specific sites)
Conclusion

 Future work and management actions

 Research and monitoring to sustain and add to the lidar survey 

and change detection datasets

 Conduct experimental vegetation removal at a small number of 

targeted sites and then continue monitoring whether the 

vegetation removal and HFE combination enhances sediment 

connectivity
The End

Thanks for listening!

Acknowledgements

 This study was supported by funding from the Bureau of Reclamation through the U.S. 

Geological Survey (USGS) Grand Canyon Monitoring and Research Center, and was 

conducted in collaboration with the National Park Service (NPS; Grand Canyon 

National Park and Glen Canyon National Recreation Area). 

 We thank:

 Brian Collins, Skye Corbett, David Bedford, David Rubin, Jack Schmidt, Paul 

Grams, Ted Melis, Ivo Lucchitta, Richard Hereford, Bob Webb, Keith Kohl, Carol 

Fritzonger, Seth Felder, Dave Foster, Mark Mastin, Katherine Jacques, 

Jacqueline Olson (USGS),

 Jennifer Dierker, Thann Baker, Rosemary Sucec (NPS), 

 Mary Barger (Bureau of Reclamation),

 Aaron Borling, Dennis Harris, Joe Hazel, Paul Rauss, Carolyn Alvord, Don Bacco, 

Kirk Burnett, Mark Perkins, Dom Zanzucchi (various affiliations)