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Last modified
7/14/2009 5:02:36 PM
Creation date
5/20/2009 10:58:24 AM
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UCREFRP
UCREFRP Catalog Number
9526
Author
LaGory, K. E., J. W. Hayse and D. Tomasko.
Title
Recommended Priorities for Geomorphology Research in Endangered Fish Habitats of the Upper Colorado River Basin.
USFW Year
2003.
USFW - Doc Type
Argonne, Illinois.
Copyright Material
NO
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Geomorphology Research Priorities September 2003 <br />planforms describe various levels of confinement of the river channel within the surrounding <br />geology, which in turn affects habitat characteristics relevant to endangered fishes. Restricted <br />meanders occur in broad alluvial terraces that are bounded by relatively more resistant geology. <br />Fixed meanders are confined by resistant geology on both outside and inside bends of the main <br />channel. Canyons consist of relatively straight sections of river with resistant geology on both <br />sides of the river. Habitat types considered included pools, runs, riffles/rapids, connected <br />backwaters, side channels, eddies, flooded tributary mouths, and flooded bottomlands. <br />Consideration also was given to potential use of reaches, assuming improvements in <br />conditions in response to implementation of flow recommendations, planned removal of existing <br />barriers to passage, and successful establishment of populations through augmentation. <br />Consideration of potential reach use was considered especially important for the razorback <br />sucker in the upper Colorado River subbasin, because existing levels of use are so low and so <br />few larvae and juveniles exist in the system. <br />Once we computed reach-habitat scores and scored the dependence of habitat <br />characteristics on hydrology and geomorphology, we searched the available literature for studies <br />that addressed important parameters in the highest scoring reaches and habitats. Remaining <br />information needs were those important relationships in priority reaches and habitats that had not <br />been addressed by previous studies. <br />In the Green River subbasin, the highest overall reach-habitat scores for species and life <br />stages combined are in the Split Mountain Canyon to Desolation Canyon reach. Habitats with <br />high scores in this restricted-meander reach include connected backwaters, side channels, <br />flooded tributary mouths, and flooded bottomlands. All are low-velocity habitats that serve as <br />critical nursery areas for Colorado pikeminnow and razorback suckers. <br />The extremely dynamic nature of backwater and side-channel habitats demands a greater <br />understanding of the geomorphic processes that form and maintain those habitats. Additional <br />research is needed to verify the existing conceptual model of backwater formation and more fully <br />understand underlying geomorphic processes, including the effects of antecedent conditions. <br />Studies are also needed to address the effects of base-flow variability (inter-annual, intra-annual, <br />and within day) on backwater and side-channel habitat availability and conditions. <br />Scores were high for spawning bar complexes in the Desolation and Gray Canyons reach <br />and in the Yampa Canyon reach because several species spawn in each. Studies are needed of <br />spawning bars in the Split Mountain Canyon to Desolation Canyon reach and in Desolation and <br />Gray Canyons to determine the effects of peak flow, base flow, and sediment characteristics on <br />the formation and maintenance of suitable spawning habitats. Although several studies have <br />examined geomorphic properties of the razorback spawning bar in the Split Mountain Canyon to <br />Desolation Canyon reach, additional study is needed to verify the existing conceptual model for <br />this bar and better understand the effects of peak-flow magnitude, peak-flow duration, peak-flow <br />frequency, peak-flow timing, and sediment on habitat conditions during the spawning period. <br />Several studies have examined the underlying geomorphic processes that affect the <br />formation and characteristics of backwaters and side channels in the upper Colorado River <br />x
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