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<br />HYDRAULIC ENGINEERING '94
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<br />Tabl~ 2. !dov~ data for mooitorcd rocks. Transport velocity is travel distance
<br />per ,!me.1R motIOI1; travel velocity is travel distance per IOtaI elasped time, Sporadic
<br />moollonng of rock l2from 1322 to 1400 hr; no apparent movement was obsetved,
<br />
<br />~otaI-r:une ~tavel Transport Ttavcl 1# Mean Step Tunes
<br />Tune IR Mabon Distance Velocity Velocity Steps Length Otain
<br />Roct~12 (s) (m) (mls) (mlmin) (mlstep) Size
<br />
<br />1209 0 0
<br />1251 637* 159 0.25* 3,0
<br />1400 637* 159 0,25* 1.4
<br />1410 1132* 412 0,36* 3.5
<br />1400-1410 495 253 0.51 29.0
<br />*max taleS assuming no motion 1322-1400 hrs
<br />Rock #17
<br />1207 0 0
<br />1241 284 141 0,50 42 18 7,8
<br />1401 284 141 0.50 1:2 18 7,8
<br />
<br />function ~ffers consid",:"bly from that measured by Schmidt and Ergenzin
<br />(1~~(Flg. 2): At this tune, the difference can be attributed to differences r. flow
<br />~uons dmmg data collection, In the case of the Phelan Creek data, the e nential
<br />funCtion fits the data well, but inadequately describes the importance of the in~uent
<br />but very long rest periods, This may be a result of the small data set.
<br />
<br />~vel distance was meas~ for all nine tadio-equipped rocks (fable I).
<br />Travel ~ and ~e1 ve~ty were compared to the size and shape pamneters of
<br />the rocks. SIIICC the bme dUtatlOll of the distance measurements varied from about 2
<br />hr t!' 4.~ hr, travel v~locit? is ~sed to the rocks, The best fit was with mass, showing
<br />a slight, IRVerse !"latI?"slnp (F.g. 3), Most comparisons were scattered, similar to that
<br />of specific gravtty, (Ftg. 3), The shon study period may account for the scattered data'
<br />a longer study penod may have allowed tbe relationships to develop more fully, ,
<br />
<br />27*
<br />27*
<br />30*
<br />3
<br />
<br />5,9*
<br />5,9*
<br />13,7*
<br />84,3
<br />
<br />77"
<br />77"
<br />181"
<br />1110
<br />
<br />91
<br />91
<br />
<br />I:::
<br />0,'
<br />0.'
<br />I:' 0.3
<br />~ 0.2
<br />Iii O.t
<br />0.0
<br />
<br />1- PhcIon c..ct '990 I
<br />-.. Schmidt and Ergenzinger(l992)
<br />
<br />W=O.43-exp-(O.043.x
<br />W=1.43.exp-(3.37.x)
<br />
<br />
<br />20
<br />
<br />8 10 12 14 16
<br />REST PERIOD (miD)
<br />Figure 2. pistribu!i"" of the d~ of rest periods with exponential function.
<br />Exponential fmction from Schmidt and Ergenzinger (1992) shown for comparison,
<br />
<br />Summarv
<br />
<br />.
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<br />6
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<br />18
<br />
<br />o
<br />
<br />2
<br />
<br />~ tracking of sediment movements in natural settings provides urn ue da
<br />unolJ!ainable ~ other methods. The Phelan Creek study, although limited b q short ta,
<br />dutallon, provides data from a period when the tracked particles were highl/mobile.
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<br />-It
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<br />189
<br />
<br />MONITORING GRAVEL MOVEMENT
<br />
<br />I.
<br />-:-; I 0
<br />i: 0 .f, 8
<br />
<br /> I.
<br /> ~I 0
<br />0 i: 0 fl~O
<br />0 0
<br />0 0
<br />.l, .,......"
<br />
<br />. .
<br />450 500 SSO 600 6SO 100 150 800 8SO 2.35 2.40 2.45 1.50 2jS 2.60 2.65
<br />MASS (g) sPECIFIC ORA VtrY
<br />
<br />Figure 3. Ttavel velocity versus particle weight and specific gravity for tracked rocks,
<br />
<br />Comparison of these data to those collected usin, a similar radio-tracldug technique
<br />bu. under different hydraulic conditions (Ergennnger and Schmidt, 1990; Schmidt and
<br />Ergenzinger, 1992), shows some similarities in transport velocity and step length but
<br />large discrepancies in the length of rest periods, Continued field stndies on a variety
<br />of fluvial systems, under varying flow and sediment transpon conditions, will provide
<br />empirical data to funher deftne the stoChastic properties of sediment transport and
<br />improve the prediction capabilities of bedload formulas and models,
<br />
<br />Reflf":l'ellCr:S
<br />
<br />Ch>cho, E.F,)r.. Burrows, R.L, and Emmell, W.W" Detection of """"'" sediment
<br />movement using radio transmitterS, Proceedings of the XXIll Congress of the
<br />International Association for Hydraulic Research, The National Research Couocil of
<br />Canada, 1989, pp, B367-B373,
<br />
<br />Chacho, E.F,)r., Burrows, R,L. and Emmett, W,W., Monitoring gravel movement
<br />in rivers, Proceedings of the Steep Streams Workshop, Corps of Engineers, In Press.
<br />
<br />Einstein. HA., The bed-load function for sediment transportation in open channel
<br />flow, U,S, Dept, Agric" Techn. Bull. No.1026, 1950.
<br />
<br />Ergenzinger,P" SchmidI,K.-H. & Busskamp,R" The Pebble Transmitter System
<br />(PETS): FIISt results of a technique for studying coarse material erosion, transpon and
<br />deposition, 7~t.'lChrift for c~""",",hnIoPie N F 33: Vol. 4: 1989, pp,503-508,
<br />
<br />Ergenzinger ,P,& SchmidI,K,-H., StoChastic elements of bed load transport in a step-
<br />pool mountain river. Aydmlo[JV in Mountainous Reirions "_Artificial ResP.I'Votrs:
<br />Water and SIOIles IAHS Publ. no. 194, 1990, pp, 39-46,
<br />
<br />Schmidt,K,-H, and Ergenzinger, P., Bedload entrainment, travel lengths, step
<br />lengths, rest periods-studied with passive (iron, magnetic) and active (tadio) tracer
<br />techniques, FNth Surface Pmcr_'..s and I.andfnnns, Vol. 17, 1992, pp, 147-164,
<br />
<br />Wolman, M.O.. A method of sampling coarse river-bed material, American
<br />Geonhvsicalllninu Ttans., Vol. 35, 1954, pp, 951-956,
<br />
<br />Yang, C.T, and Sayre, W,W" StoChastic model for sand dispersion, Proceedings
<br />ASCE. 1971, pp, 265-288.
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