FLOOD11471 (2) - Laserfiche WebLink

Home Browse Search

The hydrologic results for Spring Creek and for Templeton Gap Flood- way were developed using an SCS report entitled Procedures for Determining Peak Floods in Colorado (Reference 15). This method- ology is consistent with those outlined in the City of Colorado Springs storm runoff criteria manual (Reference 16), and has been used widely to determine design capacities for flood-control pro- jects throughout the city. For these basins, future development conditions were assumed to obtain the lOO-year frequency flow rate. Field checks were carried out to check changes in land use since completion of drainage studies, to verify channel alignments, and to check major hydraulic structures which could affect basin hydrology. The assumption of fully developed conditions in the basins was acceptable for use in the current study. Since the drainage reports contained only lOO-year peak discharges, flow rates for the 10-, 50-, and SOD-year recurrence intervals were estiw4ted in accordance with the procedures outlined in the Coloradc Springs storm runoff criteria manual and the SCS Procedures for Determining Peak Flows in Colorado (References 16 and 15). The discharge-frequency relation- ship for Spring Creek was prepared by the study contractor, using the SCS methods in conjunction with the Colorado Springs storm runoff criteria manual (Reference 16). Soil inforr.ation was obtained from an SCS survey of El Paso County (Reference 4). Peak flow rates were developed by the study contractor for the Peterson Field Drainage using the Peterson Field Master Drainage Report (Reference 17), and the Colorado Springs Municipal Airport, Runway l7L-3SR, Grading and Drainage Plan {Reference 18). Peak flows from the master drainage report were reevaluated by routing flows through the detention basins recommended in the Colorado Springs storm runoff criteria manual (Reference 16). Peak discharges for Dry Creek and its tributaries were obtained from the Dry C~eek Master Drainage Study (Reference 2). Analyses of the peak flow rates for the 10- and 50-year recurrence inter- vals were not avai:a~le. A regional relationship between basin characteristics and stream flow characteris~ics, as developed by the USGS (Reference 14) was used to define the disc~arge-frequency data for Monument Creek Tributary. The peak discharges for ~onument Creek Tributary were reduced to account for temporary storage ~pstream from small cul- verts situated under ~wo railroad embankments. Peak discharges downstrean from the railroad embankments were computed by cow~ining the reduced peak discharges t~rough the culverts and the peak dis- c~arges from the interve~ing drainage area. The SOO-year peak discharge on Monune~t Creek Tributary near the mouth also includes the 2,410 cfs that spill out of Monument Creek and flow around the north side of t~e island near tie co~f~uence of the two streams. Based on hydrau:ic analysis, tt~s overflow channel, called Monument 13