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<br />2.3. Hydrologic Analysis
<br />
<br />DCS was analyzed using the TR-20 model (Ref. 1.2), The basin was divided into seven
<br />subbasins for input to the TR-20 model. Table 2.2 shows the drainage area, CN and T c for each
<br />subbasin, The model also requires channel routing parameters to account for movement and
<br />attenuation of the flood peak. Due to the extreme variability of steep, upland channels, channel travel
<br />times were determined for flow velocities near critical. In concrete-lined channels, supercritical flow
<br />velocities were allowed,
<br />
<br />Table 2.3 shows the cumulative drainage area and peak discharge at various locations shown
<br />in Figure 2,1, The 100-year peak is less than both of the previous studies. The reduction in peak
<br />flows below the previous studies is expected due to differences in technical approach,
<br />
<br /> Table 2,2, Summary of Douglas Creek South Basin Parameters,
<br />, . " i ..'....,' ..,.i.i ;rime of ','
<br /> Drainage Area Curve Numbet' "
<br />Subbasin (squareCmiles) '..', (eN)' .'.,.".,'. I, Concentration
<br /> ,,' '." "',,,' '.'". I I~(h~rs) .
<br />A1 0,33 58,8 0,46
<br />A2 0,44 55,1 0,48
<br />B1 0,52 81.7 0,51
<br />B2 0,54 71.7 0,70
<br />C1 0,47 79.2 0,47
<br />C2 0.63 86,0 0,93
<br />D1 0,60 77.4 0,76
<br />
<br /> Table 2,3, Summary of Douglas Creek South Discharges by RCE.
<br /> > -:-' '" , "" ",' ""',.."""'"'",,,,
<br />',", ,',.' ",,' ',' '.. ',-',',--,-,-- - -,.."......,-,-- -,-"..-.
<br />Location, Drllinage Area ,',' .'" P~~Pi~9h~f9~{cffl)!?4tt!Pqt$i.)i
<br />'. (square miles) , ' , " .. " 50cyiliit .'l~ .',
<br /> , 10-year $Q91'eilr
<br />DCS1 0,85 520 810 1,010 --
<br />DCS2 0,98 230 420 560 --
<br />DCS3 1,83 710 1,170 1,490 2,100
<br />DCS4 2,30 940 1,540 1,960 2,800
<br />DCS5 0,63 490 700 940 --
<br />DCS6 2,93 1,400 2,200 2,700 3,800
<br />DCS7 3,53 1,650 2,600 3,300 4,600
<br />
<br />2,3 Resource Consultants & Engineers, Inc,
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