Fairley, Helen C. (hfairley@usgs.gov)

& Draut, A. E.; Sankey, J., Collins, B., Bedford, D. & Corbett, S.

2014 Annual Reporting Meeting, Phoenix, AZ

January 29, 2014

Landscape-scale 

management implications of 

cultural resource studies

U.S. Department of the Interior

U.S. Geological Survey
River-corridor landscape & dune fields 

set by exceptional floods (~170k cfs)

Magirl et al., 2008

 Current HFEs cover 

much smaller area 

than pre-dam floods

 Modern flood sands 

are deposited at lower 

elevations over 

smaller areas

 Transport from HFE 

deposits often 

blocked by riparian 

vegetation barriers

 So less connectivity 

between fluvial and 

upland landscapes 

today than in past
River-level sandbar Inactive sand 

Hypothesis linking dam operations, sand supply, 

wind/weather & archaeological site preservation

Dam operations altered ecosystem processes & conditions 

that used to offset effects of rainfall-induced erosion.

→ No more high floods; more vegetation; fewer open, high, dry bars 

→ Less high, dry sand = less aeolian sand to cover sites & backfill gullies 

→ Progressive deflation by wind; continuous down-cutting in gullies

HFEs & wind are only available processes for replacing high elevation sand

Vegetation

 barriers
“If you don’t know what the 

question is, you can’t figure out 

how to answer it.”

Jack Schmidt Interview, 1994 

(BQR vol.25, no. 4, p. 39)

,
Project J: 2013-2014

“Big Questions”

 Are cultural sites eroding or changing faster or in a 

significantly different manner than they would if Glen 

Canyon Dam were operated differently?

 How effective is aeolian sand at preventing or 

counteracting rainfall-induced gully erosion?

 What number / proportion of sites have the potential to 

benefit from future HFE sand deposits?
J1. Glen vs. Marble & Grand Canyons

Are sites in Glen Canyon significantly more eroded 

than those downstream in Marble and Grand Canyon 

where fine-sediment supply is greater?

 Topographic change detection at 

 4 sites in GLCA and 4 in GRCA

 Airborne lidar mapping of 8.5 miles

 Modeling of erosion
J2. Effects of HFE/modern aeolian 

sand supply on archaeological sites

Is the magnitude of aeolian transport to sites and 

deposition at sites sufficient to offset erosion?

(Do sites that are favorably situated with respect to sand sources 

and prevailing wind direction exhibit less erosion than less 

favorably situated sites?)

 Measure amounts and rates 

of deposition/erosion at 4 

sites favorably situated with 

respect to HFE sand bars 

 Compare with topographic 

change (erosion/deposition) 

at 4 Glen Canyon sites 
J3. Landscape-scale assessments

How does the degree of gully erosion differ in sediment 

deposits that are active vs. inactive with respect to 

aeolian transport?

Hypothesis: Gullies will be more extensive in 

inactive than in active sand.

Joel’s talk....
How many archaeological sites have 

the potential to benefit from aeolian 

redistribution of HFE sand?

Of the 300+ archaeological sites in the river corridor, 

what is the response of each to post-dam sand supply 

conditions and other post-dam flow effects? 

 Analyze 2012 post-HFE oblique photos, 

plus 1996 (pre- and post-HFE) and mid1980s aerial photos near each site to 

assess and source conditions

 Short field visits to identify local wind 

directions from surface geomorphology
Conditions needed for archaeological 

sites to benefit from wind-blown sand

 Sand bars deposited where wind can entrain (dry) sand

 Prevailing wind coming from “right” direction (relative 

to sand source and site location)

 No physical barriers between sand source and site
Need sand deposited where prevailing wind 

can entrain and transport it upslope to sites

1984 2009

Hypothetical example of archaeological site downwind 

of large 1984 sand bar and same location in 2009 
Tributary washes function as 

barriers to aeolian sand movement

wind
Riparian vegetation growth inhibits 

movement of aeolian sand inland

Malgosa, 2005

Malgosa, 2010
Under optimal conditions, we know 

that HFE sand will move upslope

Preliminary Data from J. Hazel, 2013– Please Do Not Cite
J2. HFE/modern aeolian sand supply to 

archaeological sites

What number, proportion of archaeological sites can 

benefit from aeolian sand supplied by HFEs?

decrease

increase

Preliminary Data from A. Draut, 2013– Please Do Not Cite

Type 1984 1996 2012

1 34% 17% 12%

2a 18% 12% 12%

2b 17% 14% 11%

2c 4% 6% 9%

3 5% 28% 34%

4 11% 11% 11%

5 11% 11% 11%
J2. HFE/modern aeolian sand supply 

to archaeological sites

What number, proportion of archaeological sites can 

benefit from aeolian sand supply caused by HFEs?

Progress as of 

December 2013; 

about half the sites 

analyzed so far 

Preliminary Data

(from A. Draut, 2013)

Please Do Not Cite
“I think it’s high time that people 

stand up and articulate more clearly 

“What are the objectives?” 

Jack Schmidt Interview, 1994 

(BQR vol.25, no. 4, p. 45)
What are the management objectives for 

cultural resources? Restore? Excavate?

2035?

Manual veg. management?

Longer high flows?

HFE protocol only?

Sediment augmentation?

Higher high flows?

Reverse the trend?

Preliminary Data

from A. Draut, 2013

Please Do Not Cite

Hypothetical Data
Questions?