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BEDLOAD TRANSPORT SAMPLING AND ESTIMATION ON Large Gravel Bed RIVERS

BEDLOAD TRANSPORT SAMPLING AND ESTIMATION ON Large Gravel Bed RIVERS. Susannah Erwin Research Geologist Columbia Environmental Research Station, USGS, Columbia, MO Work conducted while at Utah State University, Logan, UT. Ansel Adams, 1942. Snake River, Jackson Hole, WY.

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BEDLOAD TRANSPORT SAMPLING AND ESTIMATION ON Large Gravel Bed RIVERS

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  1. BEDLOAD TRANSPORT SAMPLING AND ESTIMATION ON Large Gravel Bed RIVERS Susannah Erwin Research Geologist Columbia Environmental Research Station, USGS, Columbia, MO Work conducted while at Utah State University, Logan, UT AnselAdams, 1942

  2. Snake River, Jackson Hole, WY Provo River, Heber Valley, UT

  3. Sediment budgets Input Transport Storage Output Ihillslopes Ibanks 2 alternate approaches for bedload budgets: 1. Quantifying sediment flux (measurementor modeling) 2. Determining change in storage, i.e. “morphological sediment budget” Inputs • Change in • Storage: • Dsbed • Dsbanks • Dsislands • Longitudinal patterns Terms may be partitioned into suspended load and bedload Itributaries Outputs

  4. Provo River, UT • Provo River Restoration Project: • 16 km of dikes removed, channel completely reconfigured • Downstream from a dam, and no tributaries, so assumed sediment influx is effectively zero How does a reconfigured channel, designed for a small sediment load, adjust to a large load? Sediment source Construction completed in 2004

  5. Measuring bedload transport

  6. Controlled flood experiment Developed a hydrograph that met management obligations while also facilitating measurement of bedload transport. THANK YOU BUREAU! Jordanelle Dam flood hydrograph

  7. Provo River bedload transport data Charleston (Output) Midway (Input) Life is easy when data are well-behaved

  8. Snake River, WY Has the presence and operation of Jackson Lake Dam altered the geomorphology of the Snake River in Grand Teton National Park? What are the geomorphic effects of a changing flow regime, but unperturbed sediment inputs? Area of Detail Yellowstone National Park Snake River Jackson Lake Dam Wyoming Grand Teton National Park Pacific Creek Buffalo Fork WYOMING IDAHO Moose Jackson WYOMING Snake River sampling station

  9. Snake River Bed Load Sampling Program 2006 Tributary Mean Daily Discharge • Tributaries (2006) • Pacific Creek: • 24 samples • 35 – 200% 2-yr flood • 1 – 1300 gm-1s-1 • Buffalo Fork • 39 samples: • 35 – 105% 2-yr flood • 50 – 240 gm-1s-1 • Snake River (2007) • 64 samples • 20 – 60% 2-yr flood • < 1 – 200 gm-1s-1 2007 Snake River Mean Daily Discharge

  10. Pacific Creek Bedload Transport Data How to work with less comprehensive data: Calibration uncalibrated transport relation uncalibrated transport relation uncalibrated transport relation uncalibrated transport relation • Site-specific tr chosen to provide best fit between field measurements and selected transport functions • Used transport functions of Parker (1979, 1990) calibrated transport relation calibrated transport relation for measured transport rates measured transport rates measured transport rates for

  11. Error bars bracketing calibrated transport relations vary greatly depending on patterns in transport data Pacific Creek Buffalo Fork Snake River rising limb falling limb??? falling limb rising limb falling limb rising limb

  12. ONE SAMPLING TRANSECT

  13. A few thoughts… Snake River Buffalo Fork Pacific Creek • Bedload is different than suspended load • Some (good) data is better than no data, but extrapolation can be misleading • Non-standard (non-existent?) techniques for dealing with uncertainty [guess, ignore it, application of different formulae, statistical analyses (e.g. forward stochastic, Bayesian, etc.)]

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