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7 ~ table 3. ....bu ao4 l...th or rt.., cbanaell of ""1"10... tb.. b elM UD1ted Stat.. (uc1udln. ulbutarl.. oJ~ ...U.r ......1'). Ht!an Dl'.Jn.,~ Average Totd AI'II;1 Length IAngth Inc1~ldi131 Order' NUllber (1111..> (-.ilea) Trlbv.tarl.et --- I 1,S70.000 1 J .57U.000 1 2 3S0.000 2.J 1110,000 ',.7 J tlO,OOO S.J HO .000 23 . 18,000 12 220,000 10. S 4,200 " lJ6.000 51. . 950 .. 61.000 2,lJ60 7 200 147 ]0,000 11,700 . 41 ". 14,000 55,600 , . m 6,lOO 201, ,OUO 10 1 1,800 1.1:100 l,lSo,aoo Total 3,250,000 <approx.) Riller Repreilefttatlve of Ea':b She AUtilheD}' Gilll Colllllbit Khlll..1ppi 'The definition is that of Stuhler: Order L h I::hannel without trlbutar1et; order 2 it channel with only or-der I trlbut.rI.., but Include-o only the I.oath segment between junction upstre.. of order I eh~nnel. and junction down.tre.. with another order 2 ch~nnel. Fro. Leopold et d. 1964. Fluvial Frac....n 1n CI!..ollOrpholoal.:' 'ree_n. San Fr.ncbco. The consistency of results from the numerous studies combine to fit~y establish the relationships as unchangeable llnd highly predictable "Laws." Bifurcation Ratio. Consideration of thll ratio between the number of stream segmentl of any given order to the number of segments of.the next higher order (1, 2, 3, 4) gives a consistent ratio termed the bifurcation ratio. Note in Table 4 that dividing the number of first order segments by the number of second order segments gives a ratio of 3.2; the number of second order segments divided by the number of third order segments gives a ratio of 3.3, etc. The differences in the values for the bifurcation ratios is attributed to chance v~.riations i.n the shape of any stream network. The average of the three bifurcation r,atios is 3.2 which is a good representative value for a series. Many stud.les have confirmed that in a region of uniform climate, rock typO!, and stal~e of development, the bifurcation ratio tends to re1Uin consta~lt from one order to the next and that ratios generally range between 3 and, 5 for natural stream systems. Table 4. IUureaUoa ch.ancter1aUca of W.tt. lunch above Gle1ll RUh, ...' &oc.l~vlUlt, ",arylaad. Number of Percentage Stree.s Enter1ng Arl~,1 o' Total Area of An. Number Dlnctly Into 5111111e In GIven of N~.t of Bifurcation Nut Higher Ballin Order Highest Order StualU Ratio Order (8q 11.1) l.q .,) Ord.r --- -- I 32 IS .074 2.)6 B2 2 10 J.2 . .Z66 2.8b ." 3 J J.J J .H.S 2.29 J4 . 1 3.0 6.&5t Av.r.,e TI '1'011 Leopold at al. 1964. 'Iuyt.al 'roc..... In GeollOrphoiolfl.' rreeMn. San Francisco.