FLOOD03925 - Laserfiche WebLink

Home Browse Search

2, Hydrologic Summary Peak discharges for the July 12 event for the North Fork, Buffalo Creek, Sand Draw, Spring Gulch, and other tributaries were estimated by the USGS and the Colorado Water Conservation Board, The CWCB obtained detailed surveyed cross-sections on the North Fork, Sand Draw, Buffalo Creek and Spring Gulch, It is important to note that the peak discharges occurred within less than one hour from the start of the heavy rainfall. Flow velocities in some areas were at least 15 to 20 feet per second, This situation, known as flash flooding, is extremely dangerous. Some of the peak discharge estimates are presented in Table I below. In addition to the July 12 peak flow estimates, the l00-year flow values from the Jefferson County Flood Insurance Study (FEMA. 1986) are included in the table for comparison, where applicable. These preliminary discharge estimates will be reviewed and refined as necessary. Table 1 Summary of Estimated Peak Discharges Vicinity of Buffalo Creek, Colorado CWCB USGS Jeffco Flood Estimated Estimated Insurance Stream Name Location Peak Peak Study lOO-yr Flow (cfs) Flow (cfs) Flows (cfs) N. Fork South Just d/s of confluence 16,600 10.000 to 2,300 Platte River with Buffalo Creek 14,000 Buffalo Creek Just u/s of mouth 17,100 8,000 to 630 16.000 Buffalo Creek U/S of confluence with 9,600 8,000 to N/A Snrinl! Gulch 10,000 Buffalo Creek D/S of confluence with 5.700 N/A N/A Morrison Creek Buffalo Creek U/S of confluence with 520 300 to 400 N/A Morrison Creek Buffalo Creek Intersection of Road 120 100 N/A 550 and Road 543 Sand Draw Just u/s of mouth 7,700 6,000 to 7,000 675 Snrinf' Gulch Just u/s of mouth 5,200 N/A N/A The July 12 estimated flow values are far greater than the FEMA lOO-year values, FEMA is considering a re-study of the hydrology and floodplain infonnation for portions of Buffalo Creek and its pertinent tributaries at some time in the near future, An active streamflow gaging station located on the South Platte River at South Platte (downstream of the confluence with the North Fork) recorded the flash flood event. However, it did not 6