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in 1966. Lower terraces that were frequently eroded and redeposited by unregulated flood
<br />flows are becoming stabilized by encroaching exotic vegetation. Tributary canyons continue
<br />to intermittently supply large volumes of coarse debris to the river, altering the hydraulics
<br />and navigability of nearby rapids and potentially causing long-term changes in streambed
<br />characteristics and fish habitat. Recreational visitors in increasing numbers are using the
<br />Gunnison Gorge for whitewater boating, fishing, and camping. The larger number of
<br />visitors is affecting the natural resources of the Gunnison Gorge as well as the quality of a
<br />visitor's "wilderness experience." The activities and objectives of diverse user groups often
<br />cause conflicts that the BLM must resolve. The greatest visitor use and potential for resource
<br />damage occurs in summer months when streamflows are between 30 and 85 m3/s, which
<br />is a very common range.
<br />The BLM allocates its budget, personnel, and regulatory activities based on
<br />anticipated visitor demands, which are largely dependent on the timing and magnitude of
<br />Gunnison River streamflows. The magnitude and duration of streamflow in the Gunnison
<br />Gorge is difficult to predict both seasonally and annually because of climatic uncertainty
<br />and constraints of reservoir operation. Consequentially, BLM management decisions must
<br />be amended or revised throughout the visitor season to address changing environmental
<br />conditions and visitor use. Hydrologic, geomorphic, and biologic research provides
<br />management agencies with information to better administer natural-resource areas like the
<br />Gunnison Gorge. In addition, future attempts to quantify instream flow requirements in
<br />areas like the Gunnison Gorge will benefit from studies that identify streamflows critical for
<br />maintaining a variety of natural-resource attributes and recreational opportunities.
<br />REFERENCES
<br />Auble, G.T, Friedman, J., and Scott, M.L., (in press). Relating riparian vegetation to present
<br />and future streamflow. Ecological Applications.
<br />Elliott, J.G. and Parker, R.S., 1992. Potential climate-change effects on bed-material
<br />entrainment, the Gunnison Gorge, Colorado. Proceedings paper presented to the
<br />American Water Resources Association, 28th Annual Conference and Symposia, Reno,
<br />Nevada, November 1-5,1992, p. 751-759.
<br />Shearman, J.O., 1991. User's manual for WSPRO - A computer model for water surface
<br />profile computations. Federal Highway Administration, Report No. FHWA-IP-89-027,
<br />177 p.
<br />Shields, A., 1936. Anwendung der Achnlichkaitsmechanik and Turbulenz Forschung auf
<br />die Geschiebewegung. Mitteilung Preussischen Versuchanstalt Wasser, Erd, Schiffbau,
<br />Berlin, No. 26 (in German).
<br />U.S. Bureau of Land Management, (unpublished). Project plan: Gunnison Gorge Instream
<br />Flow Assessment, Colorado, USDI Bureau of Land Management, Montrose District,
<br />Montrose Colorado, 10 August 1992,18 p.
<br />U.S. Interagency Advisory Committee on Water Data, 1982. Guidelines for Determining
<br />Flood Flow Frequency, Bulletin 17B of the Hydrology Subcommittee. Reston, Va., U.S.
<br />Geological Survey, Office of Water Data Coordination, 183 p.
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