Patch Dynamics in a River Affected by Hydropeaking

Ken Bovee¹

As part of a study conducted jointly by the Fort Collins Science Center and the Columbia Environmental Research Center, we developed several animations to illustrate the formation, deformation, and migration of habitat patches for various groups of fish in the Osage River, Missouri. We developed habitat class maps using a combination of 2-dimensional hydraulic modeling and GIS mapping, for a series of discharges at two sites in the Osage River. Both sites are downstream from Bagnell Dam, which is operated for peak-load power generation or hydropeaking. This operation results in large hourly fluctuations in streamflow and river stage. Site 1 is closest to the dam (approximately 7 km downstream) and experiences more extreme flow fluctuations than at site 2 (approximately 68 km downstream).

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The animations were developed by sequencing the appropriate map image to the measured hourly discharge at each site. These animations depict the patch dynamics of fish habitat at the two sites for August, 2001. The color key shown (right) illustrates the hydraulic and structural characteristics of each habitat class, along with the target species associated with each class.

For our analysis, we were interested in the spatial stability of shallow, slow habitat patches, represented by class 11 (pink). As you watch the animation, observe the relation between the pink patches on the map and the flow depicted on the flow meter. When the flow goes up, the pink patches disappear from the main channel and migrate into the side channels and tributary mouths. For young-of-the-year fish, we interpret this to mean that the patches in the main channel would not be suitable long-term habitat. Patches that migrate back and forth in the side channels and tributaries were considered suitable, because young fish can probably move enough to keep up with their preferred habitat.

Download the Flash Animations

 Site 1 (221 kb)

 Site 2 (137 kb)

1 U.S. Geological Survey, Fort Collins Science Center, Fort Collins, CO 80526 USA