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<br />more in some cases) to take into account the debris and sediment that were present in the stream <br />flows during the flood. In other words, a "bulking factor" wa~ taken into account, where <br />appropriate, when making the discharge estimates. Future studies may be conducted to determine <br />the amount of debris and sediment that affected the discharges. <br /> <br />The possibility of deep scouring of the channel bottoms during the flood peaks was not taken into <br />account. Typically during a flood event, channels that have an erodible bed will scour out during <br />the rising limb of the hydrograph (flood flows are increas:.ng), and then will fill back in during the <br />receding limb of the hydrograph (flood flows are decreasing). Previous studies have shown that <br />flood discharges can sometimes be underestimated by not taking into account the increased channel <br />capacity (from scouring) during the peak flows on some slIeams. This situation may be applicable <br />on Buffalo Creek and its tributaries, and should be investigated at a later time. <br /> <br />The peak discharge estimates are shown in Table 1, ,md are presented on the following figure. In <br />addition to the July 12 peak flow estimates, the 100-year flow values from the Jefferson County <br />Flood Insurance Study (FEMA, 1986) are included in the table for comparison, where applicable. <br />The preliminary discharge estimates will be reviewed and refined as necessary. <br /> <br />Table 1 <br />Summary of Estimated :Pt:ak Discharges <br />Vicinity of Buffalo Creek, Colorado <br /> <br /> CW <br /> Estin <br />Stream Name Location Pe <br /> Flow <br />N. Fork South Just d/s of confluence 16,1 <br />Platte River with Buffalo Creek <br /> .-- <br />Buffalo Creek Just u/s of mouth 17, <br /> -- <br />Buffalo Creek VIS of confluence with 9.6 <br /> Spring Gulch <br />Buffalo Creek D/S of confluence with 5,7 <br /> Morrison Creek <br /> -- <br />Buffalo Creek VIS of confluence with S.....I <br />- ., <br /> Morrison Creek <br /> -- <br />Buffalo Creek Culvert at int. of Road 12 <br /> 550 and Road 543 <br /> -- <br />Sand Draw Just u/s of mouth 7,7 <br /> -- <br /> <br />'TI <br />CB USGS <br />Jated Estimated <br />ak Peak <br />(l:fs) Flow (cfs) <br />500 10,000 to <br />1~.,000 <br />8,000 to <br />16,000 <br />8,000 to <br />10,000 <br />N/A <br /> <br />lOO <br /> <br />00 <br /> <br />DO <br /> <br />o <br /> <br />300 to 400 <br /> <br />o <br /> <br />N/A <br /> <br />DO <br /> <br />6,000 to <br />7,000 <br /> <br />Jeffco Flood <br />Insurance <br />Study IOO-yr <br />Flows (cfs) <br />2,300 <br /> <br />630 <br /> <br />N/A <br /> <br />N/A <br /> <br />N/A <br /> <br />N/A <br /> <br />675 <br /> <br />Additional cross-sections, channel slopes, and high water marks from the July 12 event were <br />surveyed by CWCB staff on August 8, 1996. Results of th~ peak flow estimates are shown in Table <br /> <br />6 <br />