HR: 1340h
AN: H13E-1369    [Abstracts]
TI: Large-Scale Sediment Routing: Development of a One-Dimensional Model Incorporating Sand Storage
AU: Wiele, S M
EM: smwiele@usgs.gov
AF: USGS Arizona Water Science Center, 520 N Park Ave., Tucson, AZ 85719 United States
AU: * Wilcock, P R
EM: wilcock@ jhu.edu
AF: Dept. of Geography and Environmental Engineering, Johns Hopkins University , 3400 N. Charles St., Baltimore, MD 21218 United States
AU: Grams, P E
EM: grams@cc.ucu.edu
AF: Dept. of Geography and Environmental Engineering, Johns Hopkins University , 3400 N. Charles St., Baltimore, MD 21218 United States
AB: Routing sediment through long reaches and networks requires a balance between model efficiency, data availability, and accurate representation of sediment flux and storage. The first two often constrain the appropriate model to one dimension, but such models are unable to capture changes in sediment storage in side-channel environments, which are typically driven by two-dimensional transport fields. Side-channel environments are especially important in canyon channels. Routing of sand in canyon channels can be further complicated by transport of sand over a cobble or boulder bed and by remote locations, which can hinder measurement of channel shape. We have produced a one-dimensional model that routes water and sand through the Colorado River below Glen Canyon Dam in Arizona. Our model differs from conventional one-dimensional models in several significant ways: (1) exchange of sand between the main downstream current and eddies, which cannot be directly represented by a one-dimensional model, is included by parameterizing predictions over a wide range of conditions from a multidimensional model; (2) suspended-sand transport over an extremely rough and sparsely sand-covered bed, which is not accurately represented in conventional sand-transport relations or boundary conditions, is calculated in our model with newly developed algorithms (see Grams and others, this meeting); (3) the channel is represented by reach-averaged properties, thereby reducing data requirements and increasing model efficiency; and (4) the model is coupled with an unsteady-flow model, thereby accounting for frequent changes in discharge produced by variations in releases in this power-producing regulated river. Numerical models can contribute to the explanation of observed changes in sand storage, extrapolate field observations to unobserved flows, and evaluate alternative dam-operation strategies for preserving the sand resource. Model applications can address several significant management issues: (1) the potentially rapid migration of tributary sand inputs through the system, which has important implications for the engineering and institutional basis for dam operations; (2) the effect of timing, magnitude, and duration of dam-release alternatives on building sand bars; and (3) the linkages between dam operations, sand deposits, and the biological, recreational, and archaeological resources along the river corridor.
DE: 1808 Dams
DE: 1825 Geomorphology: fluvial (1625)
DE: 1847 Modeling
DE: 1862 Sediment transport (4558)
SC: Hydrology [H]
MN: Fall Meeting 2005