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<br /> <br />Entrenched <br /> <br /> <br />Fnquently conf1oN <br /> <br />.~~:.: <br />- . ;':'::':~~. <br />,"',::<~' <br />~>~:...::;.:}t~ <br /> <br /> <br /> <br />32 <br /> <br /> <br />Conf tned <br /> <br />--- <br />~(", ,', ~:: <br /> <br />~~..~ <br />:lli~.:-;~':~:'_:.~~ ~~'~ <br /> <br />Occ<m1onally confined <br /> <br /> <br />Not npplic.3b le <br />FlRure 1. Confln@R1t'lIt <br /> <br />Un-confined <br /> <br />Frolll T..W. Challlberltn (ed). APD Technical Paper 2, Aquatic SllrVf'V <br />Tet'1llinology. Brithh Colulllbis Minhtry of Envh"ofUllent, Victor-ill. <br />J B. '::. 30 pages. <br /> <br />channels are those fixed in immovable bedrock which cOllfers great 10ng-tel"1ll <br />channel stability. Alluvial channels are those that hllve been formed in <br />sediment that has been transported by the stream., Channel morphology and <br />~ <br />the exposed alluviUlll reflect the type of materials transported by the water <br />over long periods of time. A semi-controlled channel jls one that is <br />predo1llinantly formed in alluvium, but does encounter be,drock and older <br />resistant alluvi\IIR, in some reaches, !lecollling fixed, illllllovable and ,stable in <br />those reaches. Bedrock and resistant alluvium can 10ciLlly dominat.! channel <br />morphology. The sediment size, sediment load, flow VelOCity, stream power, <br />width-depth ratio, and channel gradient are related to channel pattern and <br />relative stability of alluvial channels. Tb,ltrefore, channel stability is a <br />fuuttioDof the type of aaterials carried iu thewater; <br /> <br />Three types of channels are recognized on the basi,s of the type of <br />sediment being carried: suspended load, mixed load, atlld bed load. <br />Suspended Joad1s, composed of silt and clay while bed l,oad }.s compclsed of <br />sand. Ira1!elalid'rubble., Channel, fOJ:lll in response 'to the' uount elf , <br />discharae, but the pattern and shape of the channel dep,end .on the l:~pe, <br />