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<br />LARGE-SCALE AND LOCAL MODELING OF FLOW AND SAND TRANSPORT IN
<br />THE COLORADO RIvER IN THE GRAND CANYON
<br />
<br />Stephen Wiele, U.S. Geological Survey, Denver, CO; 303-236-4997; smwiele@usgs.gov
<br />
<br />Modeling of flow, sand transport, and bed evolution has been progressing at 2 scales: a 1-
<br />dimensional reach-averaged model covering tens to hundreds of kilometers, and a multi-
<br />dimensional model designed for application to specific kilometer-scale sites. The 1-
<br />dimensional model is coupled with a I-dimensional model of unsteady flow (Wiele and
<br />Smith, 1996; Wiele and Griffin, 1997) to include the effect of the propagation of daily
<br />waves released from Glen Canyon Dam. The complexity of the channel is simplified by
<br />basing the model on a reach-averaged hydraulic geometry with depositional
<br />environments, such as pools and eddies, represented by characteristic morphologies taken
<br />from the analysis of available bathymetric measurements. The purpose of the 1-
<br />dimensional model is to route tributary inputs downstream and to quantitatively estimate
<br />the effect of the operation of Glen Canyon Dam on these inputs.
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<br />The multi-dimensional model of flow, sand transport, and bed evolution has been
<br />developed and applied to kilometer-scale reaches to study depositional rates and
<br />processes for varying channel morphologies and sand supplies (Wiele and others, 1996;
<br />Wiele, 1997; Wiele and others, in press). This model is currently being applied to 4
<br />reaches between river miles 65 and 72 as part of a project funded by the Cultural
<br />Resources Program (Modeling of mainstem flow and sediment dynamics at selected
<br />cultural resources locations). The purpose of this project is to assess the effect of the
<br />operation of Glen Canyon Dam on sand bars located near water's edge. Erosion of
<br />archeological sites by the formation and propagation of arroyos has been linked to the
<br />erosion of these sand bars since the closure of Glen Canyon Dam (Hereford and others,
<br />1991).
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<br />Hereford R., Fairley, H.C., Thompson, K.S., and Balsom, lR., 1991, The effect of
<br />regulated flows on erosion of archeological sites at four areas in Eastern Grand
<br />Canyon National Park, Arizona: a preliminary analysis. U.S. Geological Survey
<br />Administrative Report.
<br />Wiele, S.M. and Smith, J.D.,1996, A reach-averaged model of diurnal discharge wave
<br />propagation down the Colorado River through the Grand Canyon: Water Resources
<br />Research,v. 32, no. 5,p. 1375-1386.
<br />Wiele, S.M., Graf, lB., and Smith, J.D., 1996, Sand deposition in the Colorado River in
<br />the Grand Canyon from flooding of the Little Colorado River: Water Resources
<br />Research, v. 32, no. 12, p. 3579-3596.
<br />Wiele, S. M. and Griffin, E.R., 1997, Modifications to a one-dimensional model of
<br />unsteady flow in the Colorado River through the Grand Canyon: Water Resources
<br />Investigation Report 97-4046.
<br />Wiele, S.M., 1997, Modeling of flood-deposited sand distributions in a reach of the
<br />Colorado River below the Little Colorado River, Grand Canyon, Arizona: Water
<br />Resources Investigation Report 97-4168.
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