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<br />HYDRAULIC ENGINEERING '94
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<br />gravel entrainment based on gravel properties. pocket properties, and mean stream
<br />hydraulics (which ~ay be directly related to stream discharge). These relationship,
<br />appear to be sufficleotly general that they may be applied to boulder-bed channels in
<br />different hydrologic and geomorphic regions,
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<br />Acknowledvments
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<br />Financial suppon for this work was provided by the Southern California
<br />Edison Company. We are also gratefol for logistical support provided by the While
<br />Mountain Research Stabon of the University of California and G. M. Kondolf for
<br />helpful conversations and assistance in selecting field sires.
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<br />References
<br />
<br />Furbish. D. 1. (1993). "Flow structure in a bouldery mountain stream with complex
<br />bed topography," Warer Resour. Res., 29(7), 2249-2263,
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<br />Kondolf, .G.M" Cada, G,F.. Sa~, MJ.. and Felando, T, (1991), "Distribution and
<br />stabthty of patennal spawmng salmonid gravels in steep boulder-bed streams of
<br />the Eastern Sierra Nevada." Trans. Amer. Fish. Soc., 120, 177-186.
<br />Wilcock, P.R, (1992). "Critical shear stress of natural sediments," J. Hydr, Eng.
<br />ASCE, 119(4),4%-501. '
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<br />MONITORING GRAVEL MOVEMENT USING RADIO TRANSMITl'ERS
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<br />Edwanl F, O1acho lr.1, William W, Emmetl2, and Robert L, Burrows3
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<br />t\l!illlIl;l
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<br />Radio transmitterS were used to track the movement of COII11le sediment particles
<br />in a IIlOUntain river during a period of high flow and high bed mobility, Transport
<br />was characterized by episodes of sediment movement separated by long rest periods,
<br />Travel distance ranged from 347 to 1065 m during the 2- to 4.5-hr study period.
<br />
<br />Introduction
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<br />Data on bedload transport in mountain rivers are scarce, especially in steep
<br />gradient streams with COII11le gravel or boulder beds where bedload samplers are
<br />difficult to use. Sediment tracking techniques, utilizing radio transmitlers implanted in
<br />individual sediment particles, have recently been developed to monitor the movement of
<br />rome sediment in natural river systems (01acho et al., 1989; Ergenzinger et al" 1989;
<br />Ergenzinger and Schmidt, 1990; Schmidt and Ergenzinger, 1992; O1acho et al.. 1994),
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<br />In lhis paper we report on a short-tenD study in which the radio tracking
<br />Iechnique was applied on a steep gradient mountain river, Results are compared to
<br />!hose of Schmidt and Ergenzinger (1992) obtained with similar radio tracking
<br />tcchniques from a smaller, lower gradient mountain river.
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<br />Instrumenhltinn
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<br />The radio traeking technique consists of sealing a radio transmitter, including
<br />,,"nay and antenna, in holes drilled in natural sediment particles. The transmitters
<br />used in this study were cylindrk:al, 18- X 72-mm units with a life of about 10 months,
<br />Nine rocks (Tablel) were equipped with radios, each transmitting at a different
<br />frequency so that each particle conld be tracked independently, A radio receiver and
<br />dire<tiooal antenna were used to locate the rocks and track their movement
<br />downstream. Two of the transmitlers were eqnipped with a motion sensor that emits a
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<br />I Resean:h Civil E~gineer, USA Cold Regions Research and Engineering Labora1ory,
<br />PO Bo. 35170, Ft Wainwright, AK 99703-0170
<br />2 Hydrologist, U,S, Geological Survey, Water Resources Division, Lalcewoad,
<br />Colorado 80225-0046
<br />3 Hydrologist, U.S, Geological Survey, Water Resow' , '; Division, Fairbanks,
<br />Alaska 99775-5170
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