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<br />CWCB staff performed field investigations on July 19, 2000 to meet with local officials, view
<br />the flooded areas, and to document flooding characteristics and damages along the affected
<br />streams, Stream cross-sections, high water marks, and channel slopes were measured with
<br />standard survey equipment. Photographs and notes were also taken to document the event,
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<br />Hydraulic analyses were performed using normal depth calculations to estimate peak flood flows
<br />for the event, Peak flows were computed for four separate cross-sections on 2 streams, The
<br />average flow velocities at each of the 4 locations ranged from 6,7 feet per second to 10,9 feet per
<br />second, and the unit discharge estimates ranged from 361 cis/square mile to 897 cis/square mile,
<br />The peak discharge estimates are presented in Table 1 below,
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<br />Table 1
<br />Peak Discharge Estimates for Flood of July 17,2000
<br />
<br /> Unit Ave, Estimated
<br /> D.A. Peak Disch. Velocity tOO-year
<br />Stream Name Location (sq mi) Flow (cfs) (cfs/sq mil (l'tIs) now (cfs)'
<br />Whiskey Gulch Approx, 500' u/s of 2,90 2,600' · 897 10,9 1,980
<br /> CR 13
<br />Whiskey Gulch Approx, 300' U/S of 2,91 1,600 550 9,5 1,980
<br /> CR 13
<br />Western Country Just upstream of 1.65 540 327 8,9 1,380
<br />Trib, d/s of pond Remington Road
<br /> crossing #1
<br />Western Country Just downstream of 0,94 340 361 6,7 970
<br />Northern tributary u/s Remington Road
<br />of pond crossing #2
<br />Western Country Just upstream of 0.55 200'" 363 N/A N/A
<br />Southern tributary u/s confluence with W,C,
<br />of pond northern tributary
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<br />Notes:
<br />. I OO-year peak flows estimated from CWCB "Guidelines for Detennining 100-year Flood Flows for Approximate
<br />Floodplains in Colorado", Subregion SPL-2 regression equation was used,
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<br />.. Flow estimate is substantially larger than that of the next downstream cross-section, It is believed that the
<br />estimate for this cross-section is too high,
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<br />... Peak flows was estimated based on drainage area ratio, not indirect flow measurement. The sum of the
<br />northern and southern tributary (340 cfs + 200 cfs) is consistent with the indirect flow measurement (540 cfs) below
<br />the detention pond for the combined flows,
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<br />Gage records are not available for any of the flooded streams that were investigated,
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<br />Flood Damages and Flood Response
<br />The flash flood event damaged roads, culverts, fences, agricultural lands, and several residential
<br />structures, Basement flooding was the main problem for several homes located within the
<br />Western Country Ranches subdivision, Fortunately, there were no human casualties or injuries
<br />that resulted from the flood event. The road crossing at County Road 13 north of Elizabeth was
<br />completely washed out when the roadway was overtopped, Existing CMP culverts at that
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