U.S. Department of the Interior

U.S. Geological Survey

Final Results of Aeolian SedTransport Study: ImplicatioFuture Weather Monitoring Colorado River EcosystemAmy E. Draut David M. RubinU.S. Geological Survey, Santa Cruz, CA
River-level sand bar Sand dun

Erosion of cultural features believed 

reduced sediment sources: loss of sandbar area 

→ less sand supply fo

deposits 

→ deflation by wind, erosi

Motivation Behind Study:
Erosion Processes at Archaeolo

Wind deflatio

Roasting feature undercut by gully

DE

INCISION
To understand erosion and deposit

processes affecting cultural sites: Studied sedimentary history, geomorp

detail using vertical sediment exposure

 Weather data collected at 6 sites; equip

operated from November 2003 to Janu

 Rainfall  Wind speed and direction Aeolian sand transport 

 All data sets used together to identify p

affecting archaeological areas, potentidam operations
Sedimentary and Geomorph

 Archaeological sites on fluvial, 

aeolian, slope-wash, distal debrisflow, and colluvial deposits. Many 

covered / preserved in aeolian sand.

 Site-specific evaluation of sediment 

at sites (Palisades, Comanche, Arroyo Grande):

 Landscape evolution in the past Modern landscape processes: 

sensitivity to dam operations

 Draut et al., 2005 SIR report; 

Geomorphology, in review; Univ. of Arizona book chapter, in review
Criteria for evaluating site sensitivi

operations (regarding aeolian sand 

1. What is the depositional context of sedimen

site was formed? (Aeolian, or other?)

2. What is the depositional context of sedimen

the site? (Aeolian, or other?)

If aeolian sediment is determined to be relevan3. Is there evidence for loss of aeolian sedime

previously covered the site? (yes/no)

4. What is the source of aeolian sediment cove5. Has that aeolian sand source been reduced? 6. Could renewed aeolian sand deposition hav

restorative effect on this site? (yes/no)

7. How could that be accomplished?
Weather Stations: Locations

Six study sites (9 weather s
Weather Stations: Measurement Ca

 Anemom

wind sp

 Sand tra

transpoland sur

 Rain ga

rainfall tgully incdetermiwet to tr

 Wind an

collectesand traemptied 
Nov 2003 - Dec 2004 Jan 2005 - Jan 
Wind and potential sand-tra

direction measured at 24.5 

Potential sand transport, by direction.Uses sediment-transport proxy variable for wind speeds that exceeded critical threshold of motion: Qp = (u - ucrit)

3

Net sand transpodunes (from direc
November 2004 High Experime

Pre-flood, 11/17/04 

1/12/06 

*

*

*

*

*

*

*
November 2004 High Experime

24.5 mile, Lower station (near river lev

24.5 mile, Upper station (upper sand du

Wind-blown sannear river level, 
Precipitation Trends

November 2003 to December 2004 January to 

Values averaged for whole river corridor (based on Are two years of data representative of long-term c
Precipitation varies greatly by 

Greatest single event measured: Hurricane Javier (9/18

Wet winter of 2005 not uniform: western canyon had more rain JanMar than some eastern sites had all year
Weather Station Network: F

 Rainfall HIGHLY variable by location  Aeolian sand transport 10 x greater in 

without much vegetation or cryptogam

 Wind speeds highest in spring (April - 

when sand transport is 5-15 times greaother times of year (implications for tim

 Effects of 2004 flood: where some (dry

flood sand remained in spring ‘05, and direction was right, aeolian sand transsignificantly higher than in pre-flood sp

 Draut and Rubin, 2005 OFR; 2006 OFR 
All aeolian deposits are not cre

 Some formed by sand 

transported from riverlevel sandbars (45,000 cfs floods can replenish their sand)

 Some formed 

reworking of ladeposits (mucwould be needsand on a larg

WIND
Our perspective...

• We view this archaeological-site preservat

a competition between two processe(creating gullies) and (2) aeolian redistr

sand (providing sand cover and filling in 

naturally trap sand).

• No way to prevent rainfall; research on rai

for documentation purposes

• The second process, aeolian transport of 

major one that management policies can amanagement purposes, studying restor

transport (and its ability to fill in gullies a

sand to dunes) is a more important foc
Malgosa: Rainfall vs. Aeo

HIGHEST PRECIPITATION of an
Palisades: Rainfall vs. Aeol

LOWEST PRECIPITATION of any stud
Malgosa Palisa

 HIGHEST PRECIPITATION HIGH AEOLIAN SAND 

TRANSPORT

 NO GULLIES OR ARROYOS

 LOWEST  LOW-MOD

SAND TRA

 LARGE A

GULLIES ARCHAEO
Malgosa Palisa

NO GULLIES OR ARROYOS LARGE ARR

→ AEOLIAN SAND TRANSPOEXTREMELY IMPORTANT FACOUNTERACTING GULLY ER

and can be managed using dam operations to maximizarea in spring windy season (when most sand transpo
Gully at 24.5 mile, filled by aeolia

from the November 2004 flood de

Head of gully 
Recommended Future Work

• Long-term weather station network, with s

distributed along river corridor (minimum representative areas of the canyon, locateareas and camouflaged). Broaden data coadding air temperature, relative humidity, pressure sensors.

• Detailed numerical modeling of wind dyna

aeolian sediment transport at selected (arcrelevant) sites. Build on modeling work doto evaluate the effects of sediment-supply sand transport: important implications for 

• Design new, automated, sand traps that re

resolution data (ideas in progress by RubiDraut at USGS, Santa Cruz).
Recommended Locations fo

Weather Stations

3

4

5

6

Minimum 6 locations, distributed along RM 0-226Representative reaches (persistent canyon orientation)Areas of low visitation
Weather Station Costs

Onset Corp. Campbell 

Scientific

Basic station (wind, precip, temp)

$1,900 $3,420 

Basic + relative humidity, barometric pressure

$2,060 $4,750 

Basic station with GOES telemetry

Not available

$8,000 

Basic + humidity, baro pressure, with GOES telemetry

Not available

$8,870 

 Maintenance, repairs: $1500 - $2500 total pe Advisable to purchase at least one set of sp

 Salary, benefits for one employee at approx
Value of Future Weather an

Sand Monitoring and Resea• Longer-term records smooth out seasona

Nino-scale variation 

→ better climate reco

many cultural, biological, physical-science 

• Better resolve causes of gully formation (e

substrate? Base level? Drainage-basin geUnusually high rainfall?) 

→ understand na

influence

• Better understand how changing open, dry 

(by erosion, vegetation, or building sandbfloods) affects aeolian sand transport 

→ c

fields and associated cultural sites. 

• Expand to more study sites 

→ continue to 

of dam operations, if any, at specific sites
With thanks to:

 Jan Balsom, Jennifer Dierker, Helen Fairle

Ralph Hunter, Matt Kaplinski, Lisa Leap, TNials, Dave Topping, Mike Yeatts; many fie

 Carol Fritzinger and many river guides