123 lines
3.4 KiB
Plaintext
123 lines
3.4 KiB
Plaintext
ends or armrgms oleeenrs lhar. a pasre nmerron ol rhe
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eeehlre (onus rhar pervade hr g namral sysmns and
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arch phenomena as rners nr lara nous
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4.16
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ORDERS OF MAGNITUDE IN
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BRANCHES
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srreams lake up many gmund pallerns dependmg on
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the processes lhar have harmed rhe undu‘ymg land.
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scape (block raulung, loldrng, vokanlsm) and rhe
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erosron and permeaorlrly rharaclerrslres nl lhe
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underlvrng rnclr .lsell llrmesrone. rnudsmne,
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sandsrone, day} That rhe ulrrmare panern 0! a
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snearn nelwork m landscape depends on pmress and
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arlolrnle, or we emrld can lhese process and more m
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hamsnlaurmodel
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We can eaerly see rhal slream pauerns are rhe sum 0!
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precedrng evenls lhar gave rrse \n lhe geologreal
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pm and luck rypes, so lhal slreanrs have a lat lo
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lell us aboul such processes, a sklll learnl rn phoro
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rnrerpreralron figure demonslrales some ol rhe
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rnlorrnalron soclearly rold by slream pallerns alone
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However, rl we ahslracr a lairly nnrrnal dendrnle
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lrreelrlrer slream branchlng parrern as m rlgure us,
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we ran hnd pm lhese lhmgs horn lhe parrern alone
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« lhe omen 0' channels. lhc rnlurrre. or sle. nl
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branches
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- The NUMBER or BRANCHES m eaeh order.
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. The TOIAL CHANNEL LENGTH in each nrder.
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. The MEANDER mqumczs m each order. or
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lhe behavmux More in me orders ol branches
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Streams usuzlly have lrnrn one lo seven orders,
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depen g on may age, srae, or gradrenl «all over
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drslaneel. An easy gradienr develops as srrearns enl
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hack lherr headwnlers and ran in laggradel rherr lower
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reaches, rneanders mcrease, and lhe velecrrv 0! (low
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decreases These older sneams, lrlre a marure lree, have
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developed all merrpranerres (is has an old (ampany or
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an old armyl Unless slrearrr cnndrlrnns lhemselves
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change (by a process 0! srream eapmre, arr mcrease m
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rarnlall, or a enange m landscapel, slrearns land
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ouslnessesr mnmlam an coorlrpnum nl order Looking
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or our dendrmr. peacelul srream, we ma_v llnd
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somelhrng as can be seen m table 4.1
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As rhe branches win up lo make ever larger orders ol
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channels, lnen dboul 3 rames as many smaller lyranshes
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10m up an make eaeh larger group, and so on
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However, rhe rndrvrdual lengrhs (ol any one branch m
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eaeh orderh rnerease by z runes as the order morass
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lrorn led. nus rs a very general rule 0! slream
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branehmg, even m nondendrrlre pallerns, and holds
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rrue [or rnany slmams Slmllarly, meanders or pends
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also occur m a predrelaole way dependrng on lhe
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volume and gradienr mom Regular meanders depend
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on renarn velocures and slream wldm lasdo slaplhry
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of Von Karman roden reads, rlgnre ml The rarro tor
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meanders or lrarls lsaoom 13.9 lVogel, WEI),
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Sueh regular )1 m pranenmg may remmd us ol
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mLsElzs lwave lronrsl, and rndeed as each srae order
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enanges, so does lhe oeharrour nol only 0! lhe waler
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llnw, mu at us assoeraled llora and hum and men
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shapes ln lhe rrlls and runnels, srreamlrnes and
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luroulenl now rs observed l-llgn m the slream
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gradients lrhe llalrened ;eurve ol lhe slream oed m
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prolrlel we lrnd rnaecls and fish wrlh sudunal parls
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alale ro suck on melee, nallened (ms Io press rhem "no
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lhe srream bed, narrened hodrer and very sneamlrned
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prolrle ln lhe rnrddle orders, we ger lees (nlbulem
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water flow, more sprralhng, less oxygenauan, and more
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”a 0’5! mmslca
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:owrrva
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(Mm
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FIGURE 4.2:
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5mm Pmmrls
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Amman lhe man Writs m mers m onm denued by me anvslaal
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sumlurrs ol lanflsciue, \nl mare M rrre and ornmhes n4-
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Assvnsme err/raps ram mews m an, ra-rreeu m2» (mum. Wm
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B‘l JDIM'UNAN xxx lm) mum hm
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Wm M Renews:
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mmnulhl: ha lhe denamrc mem
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91
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