Gregory Indivero

31 October 2011

What discharge (cfs) is required to entrain the D84 (84th percentile of sediment size distribution) in Red Canyon Wash?

What discharge was required to deposit observed flood debris from August 16, 2010 flood?

Red & Columbus Canyons

Un-gauged, Ephemeral Wash

5th Largest Drainage of CNM

Red Canyon Wash Study Reach

Fairly Straight Alluvial Channel

300 Feet Long

≅ 20 Feet Wide

Establish Reach & Cross Sections

Survey Thalweg, Flood Debris & Cross Sections

Conduct a Pebble Count at Cross Sections◦ Create Grain Size Distribution Plots

Solve Shields Equation for Critical Shear Stress, τc

Model Channel With HEC-RAS◦ -Fluctuate Discharge In Channel Until τc Is Achieved

◦ -Fluctuate Discharge Until Flood Debris Elevation is Achieved

Run Tape Measure down the ThalwegEstablish Bench Mark

Photo Credits: Gigi Richard

y = -0.0261x + 4935.3

R² = 0.9846

4926

4928

4930

4932

4934

4936

4938

0 50 100 150 200 250 300 350

Ele

vati

on in F

eet

Distance Downstream in Feet

Red Canyon Wash Long Profile

Red Canyon

Wash Thalweg

Energy Gradient

(Slope)

Surveying the Thalweg

o Slope = 0.0261

Photo Credit: Gigi Richard

Surveying Cross Section 1

Surveying Cross Section 3

Photo Credits: Gigi Richard

4932

4933

4934

4935

4936

4937

4938

4939

0 10 20 30 40 50 60

Ele

vati

on in F

eet

Distance From Left Bank in Feet

Cross Section 1

4930

4931

4932

4933

4934

0 5 10 15 20 25 30 35 40 45 50

Ele

vati

on in F

eet

Distance From Left Bank in Feet

Cross Section 3

oCross Sections 1 & 3 124 Feet Apart

100 Grains Counted At Each Cross Section

Average D84 = 24 mm

0

10

20

30

40

50

60

70

80

90

100

1 10 100 1000

Perc

ent Fin

er

Particle Diameter (mm)

Red Canyon Wash

Cross Section 1

Cross Section 2

Cross Section 3

Shields Equation◦ τc= τ*

c(ρs – ρw)gD84

Where: τ*

c = Dimensionless Shear Stress

ρs, ρw = Density of Sediment (Quartz) & Water Respectively

g = Gravitational Constant

D84 = 84th Percentile of Grain Size Distribution

τc= 0.045(9.81 m/s2)(2650-1000 kg/m3)(0.024 m)

Channel Forming Discharge = 4 cubic Feet per Second

Frequency = ??

Distance From Left Bank (ft)

HEC-RAS Model At Cross Section 1

Q = 4 ft3/s

What was the discharge of this flow?

Photo Credits: Teri Lindaur

Surveyed High Water Mark Using Flood Debris Indicators

y = -0.0261x + 4935.3

R² = 0.9846

4926

4928

4930

4932

4934

4936

4938

0 50 100 150 200 250 300 350

Ele

vati

on in F

eet

Distance Downstream in Feet

Red Canyon Wash Long Profile With High Water Mark

Red Canyon Wash

Thalweg

REW

LEW

Energy Gradient (Slope)

Photo Credits: Gigi Richard

Discharge of Flood on August 16, 2010

≈ 200 cubic feet per second

Distance From Left Bank (ft)

HEC-RAS Model At Cross Section 1

Q = 200 ft3/s

Flood Debris

Photo Credits: Greg Indivero

Video Credits: Teri Lindaur

How often do these types of flows occur?◦ Speculation

◦ Historical Events (September 7, 1978 ≈ 2,890 cfs)

Photo Credits: Jim Johnson

A Big Thank You Goes Out to the following:

◦ Dr. Gigi Richard

◦ Mrs. Teri Lindaur

◦ Mr. Con Trumbull

◦ Ms. HeidlHausner

◦ Mr. Frank Jacobs

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Cooke, R., Warren, A., Goudie, A., 1993, Desert Geomorphology: University College London, UCL Press Limited, p. 143-167.

Becker, A., DiPema, L, Ladig, K, Wellik, J, and Richard, G., 2007, Channel morphology and channel- forming discharge of No Thoroughfare Canyon, Colorado, Geological Society of America, Abstracts with Programs, Vol. 39, No. 6, p. 306

Elliott, J.G. and Hammack, L.A., 2000, Entrainment of Riparian Gravel and Cobbles in an Alluvial Reach of a Regulated Canyon River: Regulated Rivers: Research and Management, v. 16, p. 37-50.

Knighton, D., 1998, Fluvial Forms and Processes: A New Perspective. London: Arnold, p. 383

Richard, G.A., 2004, Flash Flooding at the Colorado National Monument 1921-2003: Colorado National Monument, National Park Service, p. 21

U.S. Army Corps of Engineers (USACOE), Hydrologic Engineering Center, 2010, HEC-RAS River Analysis System Hydraulic Reference Manual, Version 4.1, U.S. Army Corps of Engineers, Davis, CA, 417 pp.

Van Steeter, M. M., and J. Pitlick. 1998, Geomorphology and endangered fish habitats of the upper Colorado River: historic changes in streamflow, sediment load, and channel morphology. Water Resources Research 34:303-316.

Wilcock, P. R., 2001, Toward a practical method for estimating sediment transport rates in gravel-bed rivers, Earth Surf. Processes Landforms 26, 1395 –1408.

Wilcock, P. R., Pitlick, J., Cui, Y., 2009, Sediment Transport Primer: Estimating Bed-Material Transport in Gravel-bed Rivers, U.S. Dept. of Agriculture, Forest Service, Rocky Mountain Research Station, 78 pp.