|
<br /> TU;!; Rilin:.all IntE'flsity I
<br /> ,
<br /> (ll,ir..) ,~ If' ' ,
<br /> '..n. .r-I
<br /> 2 'Jr. 5 Yr. I 10 'ir, 25 'ir, 50 "" 100 Yr.
<br /> 5 .01 ,," ,," ,48 ,60 ,60
<br /> 10 ,36 ,48 ," ." ,84 .36
<br /> 15 ,48 i ,60 , " .9G 1.08 1.44
<br /> " ,;;0 ,8,1 .% 1.32 1.68 I 1.68
<br /> 25 ,84 1.56 2.16 2.28 2.40 3.00
<br /> ,
<br /> 3C 1.80 2,52 3.12 3.72 4.44 i 5.04
<br /> ,
<br /> 35 3.24 4.68 ,
<br /> , 5.64 6.84 7.92 9,00
<br /> 40 I
<br /> 1.08 2.04 :,.28 2.Sf! 3,24 3.72
<br /> 45 ,84 1.08 1.20 1.56 2.04 2.16
<br /> 50 ,36 ,72 .84 1.08 1.44 1.56
<br /> 55 ,36 ,60 , " .84 ,96 1.20
<br /> 60 .36 .48 .60 ,72 ,72 ,04 i
<br /> 65 .36 '. ! .60 .72 .72 .G\J I
<br />I "".1
<br />I 70 I .'" .36 ,OR ,4R ,48 .40
<br /> I , I
<br /> 75 I ' ~1 .36 .36 .36 I ,36 I ,)6
<br /> I I ,
<br /> 20 , .24 i I , I
<br /> , to ,').4 .,f; , to ,'if;
<br /> "' .'" ,24 .24 ,36 ,24 .24
<br /> 36 ." ,24 ,12 ,36 .24 .24
<br /> ,
<br /> 05 " .12 , .12 ,24 .24 ,2!,
<br /> I 'H I
<br /> 100 ,12 .12 .12 .12 2' ,,"
<br /> I ' ,
<br /> ,
<br /> 105 I ,12 .12 I ,12 ," ,24 ,24
<br /> UO I ,12 I ,12 I ,12 ,12 ,12 I ,2/,
<br /> I
<br />
<br />, U,
<br />L120
<br />TOTAL
<br />PRECTP.
<br />(tn.)
<br />
<br />."
<br />.12
<br />1.10
<br />
<br />';',,8 :~l:. ::.
<br />WSST V~NE D~AT~AGE nASl~
<br />
<br />IE:;IGN P]d~J:l\LL
<br />~-
<br />
<br />.12
<br />
<br />, " .12 ,12
<br />.12 .12 .12
<br />1.84 2,25 2.',7
<br />
<br />.12
<br />
<br />,12
<br />
<br />2.89
<br />
<br />P"'t"Cf'nt
<br />of
<br />Total
<br />
<br />1.7
<br />U
<br />U
<br />4.8
<br />8,7
<br />14,5
<br />26,0
<br />10.7
<br />6.2
<br />U
<br />L5
<br />2,4
<br />
<br />1,7
<br />
<br />1.2
<br />l.Q
<br />1.0
<br />0,7
<br />0.7
<br />0,7
<br />0,7
<br />
<br />0,7
<br />
<br />0,7
<br />I),j
<br />0,3
<br />
<br />C?.{.)
<br />
<br />. 1 2
<br />
<br />1.55
<br />
<br />nh1:
<br />
<br />I UBL.~
<br />
<br />DESIGN RAINFAll
<br />
<br />-, ~-
<br />
<br />i
<br />,
<br />I
<br />I
<br />I
<br />
<br />hi1sed model. Accuracy is del-'endent on repr~scntinq th" act:u,1l
<br />physic<:<l characteristics in the field. Therefore, significant
<br />changes in overland flow slopes, ext~nt or type of develop-
<br />ment, and overland flow lengths were represented by modelling
<br />smaller subbasins. The subbasins we!'e deline"ted using the 100
<br />scale, 2 ft, contour interval mapping provided by the City,
<br />Field investigations were carried out as necessary to define
<br />those subbasin boundaries difficult to determine from mapping,
<br />Subbasin sizes ranged from 1,8 acres to 156,8 acres with the
<br />median size being 14,3 acres <:<nd the average size being 25.5
<br />..cres,
<br />
<br />IV.D. Influence of Physical Features on Hydrology
<br />
<br />As stated previously in this report, several existing detention
<br />and retention areas exist throughout the drainage basin, sone
<br />of which are natural whilf' others are caused by road embank-
<br />ments, railroad embankments, or development. ~any of these
<br />are<:<s exist west of Dverland Trail on property owned by C.$.U,
<br />All existing detention <:<nd depression areas were modelled [or
<br />the existing dev"lopment condition, The City has little
<br />control over future dcvelopreent on C,S,U. property, Therefore,
<br />for thi> hydr"'lo<ji" "'1"'ly"j" of f1ltur-' d,"v""l(]p"""nr, rhro\lgh
<br />mutual agreement with the Technical Committee, existing dctllntion
<br />and retention areas east of Overl<:<nd Trail were modell(>d <:<s
<br />they ~xist, Detention areas west of Overland Trail were
<br />eliminated with the exception of College Lake. College Lak",
<br />was modelled <:<s a detention facility <:<ssuming the lake was full
<br />to th~ crest of the e~rgency spi1lw<:<y at the beginnir.g of the
<br />des~gn storm. D~sch"rge ch<:<racter~stics tor the spillwdY as
<br />prcs~nted in the "College Lake Improvements Study" 11) Wrl1re used,
<br />
<br />The four irrigation canals which traverse the drain"ge basin
<br /><:<1'''' Capable of int.ereepting a siy-r.ificant portion of minor
<br />stOITI runoff bas,~d on current. lE~'''f>l$ of (leveloprr-cnt 'Nith the
<br />assumption ~hat the c~nals are not running full with irrigation
<br />'~'ater. However, for purposes of this hydrologic analysis,
<br />
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