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<br />however, the contamination thre~t to danesti~ weter supplies cannot
<br />be illu.trated with similar e~se.
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<br />main ch~nnal, except where flows Dan return through th~ main frBe-
<br />~~y undorpasses. High velocities and vari~ble depth ~ondition8 G~n
<br />be expected in the vicinity of thess embankment openings.
<br />
<br />Floonod Are~s and FIQnrl D~~~~~
<br />The ~re~~ ~long Monwmont Craek flooded by the St~ndard
<br />P~ojoct Flood, Intermediate Rsgianal Flood, and the May 1935 flood
<br />of re~ord are shown on Platns :3 through 7. OBpths of flow for any
<br />give~ stroaM lOGotion c~n be eatimntad from the high water profiles
<br />shown on Plntes e through 12. Plates 12 and 13 show sslected cross
<br />sections of the creek that are typical of the 40. s5ctions surveyed
<br />in th~ Mo~u~ent Creek .tudy r~ach; ell cro~s sectio~ locations ars
<br />shawn on ths floodso area and profile plateB. Stream characteris-
<br />tics detarmin~d from topogr~phic naps, ~sriel photogrBphB, and v~l-
<br />l~y CrC3C $ection~ ~ers u~ed to comp~te and define th~ flood situ~-
<br />tion.
<br />
<br />Floadw~ter p]pv~tions determined in any particular cross
<br />,,~r;tiol\ ~l'''~ are not alw~yc indi~ative of th,~ dBpth" ~dually at.
<br />t~ined. Oft"n, floodUJater~ becnme i~ulated ",'d ent.apped in OVA~-
<br />bonk ~~e'>S r,,~ulting in flooding dBpthe 9~e~te~ th"" thO>lB "hawn an
<br />thflhiqh""terp.cfU"a.
<br />,j.u lnter"..ediilto Hegiancl Flood w"'Jld h~ ge"p~~lly non-
<br />tainsd in thc ~ell_cnt~enched ~Qnunent C.eek dhanne~. IhB greater
<br />5tanda.d Project Flood would ov"rflm, " oli~htly lar~er "re" than
<br />that coverBd by the hi~toric ~"y 1935 floed, thu~ c"u~in'J greater
<br />fleod dnmages th~n p.Bvi~~~ly experiBoced.
<br />Flo"o1w"te.s br"~ching the Illest b~nk "~ar th.. M"nu"'~nt
<br />~~Lloy P~.k ~~i"ming pool ~ill .each to Pi no Streot until nesr the
<br />"r,?~ 0f iIi~~t Atj"" Street. The fluw ~o'Jld ~h"n ~xp~nd farther
<br />~est, cros~ing 5p.vce and W3lnut 5tr~eta to ne~r the int".section
<br />af Che"tn'~t ~"d Pik~'. Pp-~k ~venlle: then. ccntinue south 810'"'9 thesa
<br />~t.ed. into the lo..er flood pI "in. The p.Q:rinent lnterst3te High_
<br />~"Y 25 ",,,,l1,,n,,mo,,t ~ill hold thege fl,,"dw~t~~e iflol"ted frorr, tIle
<br />
<br />Velocities, Rates llf Rise, and Duration
<br />The occurrence of the lnter~ediste Regional or Standard
<br />Project Flood would re~ult in ths flood cheracte~ietice sho~ in
<br />Teble 5. This dsts rBflects the eve~aged maximum conditions with
<br />heights of riBe, rates of rise, end durations of flooding measured
<br />above bankfull stege.
<br />floodfiow velocities depend upon tho gBoeral waterway
<br />configuration, and the size, shape, and olope of streambed and over-
<br />b~nk flow areas. AVBrage velocitiBs may range from tho maximums
<br />appea.ing in Table 5 to less then 50 parcent of theso value.. On
<br />30 ~ay 1935, the flooding duration weS approximately 4.5 hours sa
<br />comperod to the 9.0 and 10.5 hours estimated fo~ tho Inte.mediate
<br />Regional and Standard Project floods, respectively, in the lower
<br />reach which extends th~ough urban Colorado Springs.
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<br />Obstructions
<br />
<br />aJ.'u~h ""J J..bd~ ..",,,,1,1"'J duwnstL's,,," duriny floo,;" ofto",
<br />collect against bridges or within any .eatricted flow area, .e~'cing
<br />the weterway openings and othe~wise impeding floodflow. This
<br />creotes a damming effect and, depending upon the d09.eO of ~l09.
<br />ging, Causes g~eator backwater dopths with increased overbank flood_
<br />ing. Wate. pressu~e, building against embankments and b.idges, con
<br />then result in serious erosion, stress danage, o. total destruction
<br />of the structu.e involved. A pronou~ced increace in flo~ velocities
<br />ususlly occurs do~nstrea~ fro~ an obstruction, thu~ extending the
<br />flood'sdamegapotential,ObstructlvenewdevalopmBntaodfutura
<br />land filling in o. neat the strBam's floadway ~dn be a major f~~t~r
<br />in multiplying the ~dverse effects des~ribed, One problo~ channel
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