Laserfiche WebLink
<br />. <br /> <br />. <br /> <br />. <br /> <br />There have been several high water events on the Wiley Drainage Ditch at Wiley. The most recent <br />high water occurred during 1995. A storm on May 26, 1995 dumped heavy rain and hail over the <br />basin. An average of 3 to 5 inches of precipitation was reported for a portion of the basin, with <br />point precipitation amounts in excess of 6 inches. A large amount of hail was generated from this <br />storm, and the hailstones collected along certain drainageways to form "dikes" that actually helped <br />to protect certain buildings from being flooded more severely. Previous rain events, which <br />occurred during the two weeks prior to the May 26th storm, caused the soil within the basin to be <br />quite saturated. The May 26 flood caused damage to homes, bridges, roadways, vehicles, <br />equipment, livestock, farm lands, wells, drop structures, irrigation flumes, and other features. The <br />drainage ditch itself incurred damage in the form of bank erosion, channel scour, and debris <br />accumulation. Flow in the Wiley Drainage Ditch overtopped Highway 196 by about 1 to 2 feet, <br />according to Town officials. The approaches to both sides of the bridge were washed out during <br />the flooding. High water reached the first floor windows of several houses in the Gold Addition <br />subdivision located on the northeast end of town upstream of Highway 196. The flooding was well <br />documented by video and photography that was taken by local residents. The Colorado Department <br />of Transportation (CDOT) estimated a peak flow of 8,100 cfs for this flood. Based on 100-year <br />peak flow estimates discussed later in this report, the May 26th peak flow was on the order of a 25 <br />to 50-year event. <br /> <br />Another major storm over the Wiley drainage basin in 1995 occurred on June 3rd. That storm <br />produced heavy rainfall without very much hail. Flooding from the June 3rd event was not quite as <br />severe as the May 26th event, however high water caused substantial damages in Wiley for the <br />second time during 1995. Other high water events in Wiley have occurred in the past, but very little <br />recorded information is available to document the flood history. <br /> <br />Other Studies <br />A Flood Hazard Boundary Map, dated July 1977, was published by the Federal Insuamce <br />Administration for unincorporated Prowers County, but did not include flood hazard areas for the <br />town of Wiley. There are no previously published floodplain studies or floodplain maps that have <br />been produced for Wiley. The Corps of Engineers published a floodplain study for the Arkansas <br />River and some of its tributaries, but the Wiley Drainage Ditch was not evaluated in that study, A <br />new study for the Wiley Drainage Ditch, including hydrology and hydraulics, was completed by <br />Sear Brown, Inc. on behalf of the Colorado Department of Transportation as part of a roadway <br />improvement project on Highway 287, The Sear Brown work has not been formally adopted or <br />published at the time of this study, <br /> <br />ENGINEERING METHODS <br /> <br />HvdrolOl!ic Analvsis <br />Discharge-frequency relationships for the Wiley Drainage Ditch were based on regional <br />regression equations for Colorado. The regression equations are published in the USGS Water- <br />Resources Investigations Report 99-4190 "Analysis of the Magnitude and Frequency of Floods <br /> <br />3 <br />