HR: 1340h
AN: H53B-1239    [Abstracts]
TI: Flow and sediment-transport modeling of Kootenai River White Sturgeon Spawning Habitat.
AU: * McDonald, R R
EM: rmcd@usgs.gov
AF: U.S. Geological Survey, MS 413 Denver Federal Center, Lakewood, CO 80225 United States
AU: Nelson, J
EM: jmn@usgs.gov
AF: U.S. Geological Survey, MS 413 Denver Federal Center, Lakewood, CO 80225 United States
AU: Barton, G
EM: gbarton@usgs.gov
AF: U.S. Geological Survey, Boise Field Office 230 Collins Road, Boise, ID 83702 United States
AU: Paragamian, V
EM: vparagamian@idfg.state.id.us
AF: Idaho Department of Fish and Game, 2750 Kathleen Ave , Coeur d'Alene, ID 83814
AB: The population of White Sturgeon in the Kootenai River downstream of Libby Dam in Montana and Idaho has declined since the construction of the dam in 1972. The White Sturgeon was listed as endangered in 1994 and an 11.2 mile reach of the river, downstream of Bonners Ferry, Idaho was designated as Critical Habitat in 2001. It is hypothesized that hydro-electric and flood control operations have contributed to poor spawning habitat and recruitment of juvenile fish. The successful incubation of eggs requires a stable and coarse bed material. Currently the sturgeon are spawning in a reach of poor substrate consisting of dunes up to 2 meters in amplitude and composed of fine sand while a short distance upstream there is suitable substrate of coarse gravel. We present here the preliminary results of a flow and sediment-transport modeling effort to aid in an understanding of both the current spawning habitat of the White Sturgeon and the potential to artificially enhance the current spawning habitat or to influence the sturgeon to move upstream to more suitable habitat. A 2.5 dimensional flow model was constructed for an 8-kilometer reach of the designated Critical Habitat. The modeled reach consists of several broad meanders and a mid channel island. The substrate is composed of fine sand with a median grain size of 0.22mm and has large dunes up to 2m in amplitude at relatively lows flows of 200 cms that wash out to a plane bed at around 600 cms. The model has been calibrated to a range of historical flow conditions from 170 cms to 1709 cms and verified against 16 ADCP velocity cross-section profiles collected during a period of steady flow at 554 cms. The model predicts well most of the salient features of the velocity field including the magnitude and location of the secondary flow, using a simple constant value for roughness. However for a few reaches of the river the bed forms and their spatial variability in size are shown to significantly affect the flow and the performance of the model can be enhanced by assigning a variable roughness. Over the range of modeled flows most of the bed is highly mobile. Comparison of the model results for velocity, bed shear stress and depth to the locations of known spawning activity show that spawning locations are found in and downstream of deep holes with high velocity.
DE: 1803 Anthropogenic effects
DE: 1815 Erosion and sedimentation
DE: 1821 Floods
DE: 1824 Geomorphology (1625)
DE: 1857 Reservoirs (surface)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting