FLOOD03288 - Laserfiche WebLink

Home Browse Search

TABLE A-'I. MODELED PEAl{ DISCHARGES AT THREE SITES (Dischar~res in ,:::fs) LOCATION 10-YEAR 50'-YEAR 100-YEAR SOO-YEAR Highway 52 County Rd. Wiggins 16,900 16,300 14,200 36,900 36,400 36,000 49,900 49,400 49,300 96,800 96,300 96,000 A-2 Hydraulics Discussion A-2.1 Purpose of Study This study wa.s conducted t,::>:: 1) Determine, the stage-di::scharge rating for Kiowa Creek at the Colorado state Highway S;! (HWY 52) and Weld County road bridges locate,d in the SW1/4SE1/4 , SEC. 5, T1N , R61W and the NW1/ 4SW1/ 4 , SEC. 31, T3N , R60W ,rE=spectively. These rating curves were used to de,sign a flood '/arning gage at each bridge. 2) Develop travel times between the two flood warning gages and the closure structures located in Wiggins. 3) Analyze the rating curves for the two closure struc- tures in Wiggins presented in Appendix F of the 'Wiggins 0 & M Manual, 1989"'. A-2.2 Area Studied 1) Kiowa Cre,ek from the tmm of Wiggins, Colorado to the Hwy 52 bridge. 2) Reach length - approximately 15 miles. 3) See Figures 1, A-1 & A-2. A-2.3 Data Sources 1) U.S.G.S. 7.5 minute series topographic mapping with ten foot contours and a scal,e of 1" = 2,000'. (Base maps are from 1950, some! were revised in 1978.) 2) Cross sections at the Hwy 52 bridge and the Weld County road bridge ~Iere surveyed in 1988 and supplied by the Colorado Water Conservation Board (CWCB). 3) HEC-2 decks, modeling 'the two closure structu.res sup- plied by the CWCB (from here on referred to as the CWCB mod- els) . A-2 . 4 Hydrology The hydrology for this study was provided by the C:WCB. The peak discharges at wiggins are list,ed in Table A-1 for each recurrence interval. A-2.5 Hydraulic Analysis HEC-2 models were developed for Kiowa. Creek at the Hwy 52 bridge and the Weld County road bridge using similar model- ing procedure!;. Water surface profiles were computed using the HEC-2 backlvater program. The HEC-2 program (Filename = HEC2CUL.EXE) was run on an IB:M compatible: 286 microcomputer. 29