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<br /> ". $A'lClERSQ,'l GIJLC"1
<br /> SuA B~SI~ , TDTAL ~EVELOP"'ENT
<br /> 1~:l YEAIl STOR" HYCIlOGi'lAP""
<br /> , <, DURA 71 O,~
<br />A"FA . a.254 SO , , ST:iR" TOEA< . 50 1>'1."
<br />LE"Gr.... . O.107~ "ILES 570R.\1 QPO:AK . 340. ,<S
<br />L Fr~ G T H -C A . 0.265 ....IL~S QP/A( . 2.095 CFS/AC
<br />PFRVIOU5 . 0.65 OlliS"! . 1341. CFS/SO "
<br />I"PICIlV!OuS.. 0.35 TOTAL "'<EeIP . 2.49 "
<br />!.';""ILll...<<I" 0.750 " EXCESS PREClo . 1.34 '"
<br />LOSS . O.:J50 u'>IT vaLU"':: . 13.5 ,"
<br /> STOR'" VOlU"E . 1 8 . 7 ^'
<br /> STOR... EXCESS U"l1T STDR"1 I
<br /> Tl"1E plll'e!!> PREClo HYDRO .,VORO
<br /> O'INI (I'll IINI (CFSI le!"SI I
<br /> 0 :l.ao 0.00 o , 0,
<br /> 10 0.13 0.01 189. , I
<br /> ..
<br /> 10 0.17 0.06 281, , , ,
<br /> " 0.35 0012 163. 30. ,
<br /> ,
<br /> " 1.03 0.78 106. 107. I
<br /> ;0 0.27 0019 69, 340.
<br /> 00 Cl.lS 0.07 " , 248.
<br /> " 0,09 0.03 ", 176.
<br /> BO 0.07 0.02 19. 123.
<br /> 50 !'l.07 0.02 ", a.9.
<br /> 100 :1.06 C.M , , ^"
<br /> 110 o.o~ 0.02 ; . '9.
<br /> 110 o . 0 5 0.02 , , 10.
<br /> no , . 50.
<br /> 1 " 1 , l~.
<br /> 150 , . 12.
<br /> 100 o , , ,
<br /> l10 ^ , ,
<br /> .,
<br /> 180 O. ,.
<br /> 190 o . "
<br />
<br />these figures with those recommended in the ~anual, it was
<br />determined that the following coefficients could be used
<br />throughout the total study area.
<br />
<br />Infiltration
<br />Pervious Storage
<br />Impervious Storage
<br />Loss
<br />
<br />0.75 in/hr
<br />0.50 in
<br />0.30 in
<br />"
<br />
<br />The degree of development, of course, varied for each subdivision.
<br />
<br />DESIGN POINTS
<br />
<br />There were a total of 44 design points or sub-basins designated
<br />for this project. The breakdown in each gulch was: Main
<br />Sanderson Gulch, 14, South Sanderson (south of Jewell and west
<br />of Garrison), two; North Sanderson Gulch, six; Main Weir Gulch,
<br />18; North Weir Gulch, two; and South Weir Gulch, two. The design
<br />points were set at road crossings, reservoirs, and points of
<br />channel confluence. Also, design sub-basins were sized to about
<br />200 acres with some exceptions, particularly off-channel basins.
<br />The relative location of the design points are shown in the
<br />overall basin maps, Sheet No.2 and 3 in Volume No.2.
<br />For each point, the peak storm runoff rate was computed for
<br />conditions of existing and total development, as required in
<br />the contract. A summary of the flows is provided on the
<br />Discharge Probability Profilcs for each gulch as discussed
<br />in the following ,;ection.
<br />
<br />SUMl1AR'i OF HYDROLOGICAL DATA
<br />A s~mmdry of all the input and output hydrological information
<br />which w...~ used in the study of the Sanderson and Weir Gulches
<br />has been submitted to the Drainage District for their records.
<br />In summary, the information includes the description of the
<br />physical features of each sub-basin including the area, length,
<br />length to centroid and slope; the ass~~ed degrce and typo of
<br />development including the degree of perviousness and imper-
<br />viousness; the coefficients used for each type of development
<br />assumed within the sub-basin and all other hydrological para-
<br />meters u,;ed in the analysis.
<br />
<br />Figure III-3
<br />
<br />Sample Computer Output
<br />
<br />A summary of the hydrologlcal study lS proVlded ln thlS report
<br />in the form of Discharge Probability Profiles and selected
<br />actual storm hydrographs at particular design points. The
<br />discharge profiles for the existing and developed conditions
<br />of Phase ^ and the final hydrology of Phase a are presented in
<br />Figure 1II-4 through Figure 111-13 as follows:
<br />
<br />-26-
<br />
<br />-27-
<br />
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