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<br />. <br /> <br />T <br /> <br />. <br /> <br />--- <br /> <br />766 <br /> <br />HYDRAULIC ENGINEERING '94 <br /> <br /> <br />614 ,~j <br />612 C <br />610 <br />608 <br />608 ./' <br />604 <br />602 <br />600 20 40 60 <br />20 -60 -40 -20 0 <br /> <br />614 <br />612 <br />610 <br />608 <br />608 <br />604 <br />602 <br />600 <br />-100 <br /> <br />a <br /> <br /> <br />~ -60 -40 -20 <br /> <br />o <br /> <br />614 <br />616 612 <br />614 610 <br />612 608 <br />610 <br />608 608 <br />606 604 <br />604 602 <br />602 600 <br />600 20 0 20 40 60 80 100 <br />-100 ~ -60 -40 -20 0 20 - <br />.......... andwatet swfaceatthe flfSt foW' <br />Figure 2. eompoualive pofiles ofbo_.....A.y 1I1e fuJ1hest opstrellJl\and d Islocale<! <br />-secUons shown in the upstreatn pan of fig. 1. IS <br />= beginning of the debris fan. <br /> <br />1 300 1-' - Post-~~ <br />~~\ ~Pr:~ 11,- ,- /' ",-,-./ <br />"1~ ~.-, --y <br />~ 100 ' <br />" _^ I \.. ..\.." I, ,0 .1." .1.., .1 <br />... o;IIU ...1"..1.".1..... ....... <br />:I 0 200 150 100 -50 0 SO 100 1SO 200 <br />~ -300 -250 - - - <br />610 <br />!608 <br />~608 <br />.. 604 <br />~ 602 <br />ILl <br />600 <br />-300 <br /> <br />~\.d <br />.-- . <br />\'-.. _ M. ~:.- <br />. ./ <br />\ . <br />,/ <br /> <br />~.~-=:-;--~.~=~ <br /> <br />~~:-~-::' <br /> <br />----~._-.- .1 <br /> <br />-250 -200 -150 -100 -50 0 50 100 150 200 <br />Longitudinal distance (m) <br />, '1lIdinlll proIiue> of bot\OD1lOpography. <br />Figure 3. comparative longa _ and post-flood conditons <br />water -surface topOgraphY and shear stress fot JR <br />111415 ems. <br /> <br />. <br /> <br />FLUVIAL HYDRAULICS OF STREAMS AND l<<JUNTAIN RIVERS WITH l<<lBILE BED <br />WoJclech BARTNIK~AllcJa MICHALIK' <br /> <br />Abstract <br /> <br />The local hydraulic conditions concerning the incipient !lOtion of <br />the bed material In aountaln streaas are considered. Resul t5 of <br />Masurements carried out by using the radioisotope tracer M:thod In <br />natural streams are foundation of an analysis of the critical shear <br />stresses in non-uniforll bed ma.tertal. The grain size and the grain <br />shape effect on the incipient movement of the bed load transport <br />are presented. <br />Key Words: <br /> <br />bed load, Incipient motion, grain size, grain shape,critical shear <br />stress, radioisotope pethod <br /> <br />Introduction <br /> <br />Studies of a transport of the bed load f'or lIOuntain rivers were <br />carried out by melUlS of' radioisotope methods which made <br />doter_ination of conditions of incipient movement individual of' bed <br />fractions (Michalik & Bartnik 1986) and quantlty of the bed <br />...terlal transported during a flood (Michal1k 1991).Results of' <br />aeasurements carried out on four rivers showed that It was <br />necessary to consider local hydraulics parameters in the river <br />cross section In order to determine correctly the transport <br />condi t Ions of non - unUorm material. For dlf'f'erent rivers the <br />dlfft'rent correlations between critical stresses and a grain size <br />thldlng function) were obtained what was appl1ed to modif'y the <br />K&~f:r - Peter and HUller for.ula (Michalik 1991), However, the <br />oquat Ion of transport for any lIOootaln rl ver was not <br />0btalned. Therefore ,studies , which IIlllY be proVe! effect also the <br />other p&r8Jlleters on the moveMent conditions of' the bed material of <br />aountaln rivers are beings till carried out such a para.meter can be <br />. 8f...ln shape. Paving of bottoll., wedging one another of the different <br />.\ze gralns and their transport f'lexlbility depend significantly on <br />the gratn shape. <br />, <br />bartntk dr hab. eng. <br />. <br />Hlchal1k dr bab. eng. <br />Dtpartent of Water Engineering Agricultural University of Cracow <br />Poland,30-oS9 Cracow al.Micklewicza 24/28 <br /> <br />767 <br /> <br />-- <br /> <br />- <br />