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

Transcription

1 Gregory Indivero 31 October 2011

2 What discharge (cfs) is required to entrain the D 84 (84 th percentile of sediment size distribution) in Red Canyon Wash? What discharge was required to deposit observed flood debris from August 16, 2010 flood?

3 Red & Columbus Canyons Un-gauged, Ephemeral Wash 5 th Largest Drainage of CNM

4 Red Canyon Wash Study Reach

5 Fairly Straight Alluvial Channel 300 Feet Long 20 Feet Wide

6 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, τ c Model Channel With HEC-RAS -Fluctuate Discharge In Channel Until τ c Is Achieved -Fluctuate Discharge Until Flood Debris Elevation is Achieved

7 Run Tape Measure down the Thalweg Establish Bench Mark Photo Credits: Gigi Richard

8 Elevation in Feet Surveying the Thalweg o Slope = Red Canyon Wash Long Profile Red Canyon Wash Thalweg Energy Gradient (Slope) y = x Dis tance Downstream in Feet R² = Photo Credit: Gigi Richard

9 Surveying Cross Section 1 Surveying Cross Section 3 Photo Credits: Gigi Richard

10 Elevation in Feet Elevation in Feet Cross Section ocross Sections 1 & Feet Apart Dis tance From Left B ank in Feet Cross Section Distance From Left Bank in Feet

11 Percent Finer Red Canyon Wash Cross Section 1 Cross Section 2 Cross Section Particle Diameter (mm) 100 Grains Counted At Each Cross Section Average D 84 = 24 mm

12 Shields Equation τ c = τ * c(ρ s ρ w )gd 84 Where: τ * c = Dimensionless Shear Stress ρ s, ρ w = Density of Sediment (Quartz) & Water Respectively g = Gravitational Constant D 84 = 84 th Percentile of Grain Size Distribution τ c = 0.045(9.81 m/s 2 )( kg/m 3 )(0.024 m)

13 HEC-RAS Model At Cross Section 1 Q = 4 ft 3 /s Distance From Left Bank (ft) Channel Forming Discharge = 4 cubic Feet per Second Frequency =??

14 What was the discharge of this flow? Photo Credits: Teri Lindaur

15 Elevation in Feet Surveyed High Water Mark Using Flood Debris Indicators 4938 Red Canyon Wash Long Profile With High Water Mark Red Canyon Wash Thalweg REW LEW Energy Gradient (Slope) Dis tance Downstream in Feet y = x R² = Photo Credits: Gigi Richard

16 HEC-RAS Model At Cross Section 1 Flood Debris Q = 200 ft 3 /s Distance From Left Bank (ft) Discharge of Flood on August 16, cubic feet per second

17 Photo Credits: Greg Indivero

18 Video Credits: Teri Lindaur

19 How often do these types of flows occur? Speculation Historical Events (September 7, ,890 cfs) Photo Credits: Jim Johnson

20 A Big Thank You Goes Out to the following: Dr. Gigi Richard Mrs. Teri Lindaur Mr. Con Trumbull Ms. HeidlHausner Mr. Frank Jacobs

21 Arcement, G. J., 1989, Guide for selecting Manning's roughness co-efficients for natural channels and flood plain, USGS water-supply paper: 2339, v. 38. Cooke, R., Warren, A., Goudie, A., 1993, Desert Geomorphology: University College London, UCL Press Limited, p 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 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 : 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: Wilcock, P. R., 2001, Toward a practical method for estimating sediment transport rates in gravel-bed rivers, Earth Surf. Processes Landforms 26, 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.