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A portion of Monument Creek south of Woodman Road has been channelized. Thi s improvement has' considerably reduced the extent of the 100-year flooding in this area. 3.0 ENGINEERING METHODS For the flooding sources studied in detail in the community, standard hydrologic and hydraulic study methods were used to determine the flood hazard data required for this study. Flood events of a magnitude which are expected to be equaled or exceeded!once on the average during any 10-, 50-, 100-, or SOO-year period (recurrence interval) have been selected as having special significance for flood plain management and for flood insurance rates. These events, commonly termed the 10-, 50-, 100-, and SOO-year floods, have a 10, 2, 1, and p.2 percent chance, respectively, of being equaled or exceeded during any year. Although the recurrence interval represents the long-term average period between floods of a specific magnitude, rare floods could occur at short intervals or even within the same year. The risk of Elxperiencing a rare flood increases when periods greater than 1 year are cpnsidered. For example, the risk of having a flood which equals or exce~ds the 100-year flood (1 percent chance of annual exceedence) in any iSO-year period is approximately 40 percent (4 in 10), and, for any 90-year period, the risk increases to approximately 60 percent (6 in 10). the analyses reported herein reflect flooding potentials based on conditior)s existing in the community at the time of completion of this study. :Maps and flood elevations will be amended periodically to reflect future 'changes. . 3.1 Hydrologic Analyses Hydrologic analyses were carried out to establish the peak discharge- frequency relationships for each: flooding source studied in detail affecting the community. Peak discharge-frequency relationships for streams studied in Colorado Springs were developed: from one of four sources: (1) material prepared by the COE (ReJ!erence 6), (2) existing flood plain reports designated by the State of Colorado for flood plain regulation, (3) from new hydrologic data developed by COM, or, (4) from existing hydrologic reports by private firms. The following discussion summarizes the hydrologic analysis and results for each stream studied. ' The hydrologic analysis used fqr this Flood Insurance Study for Fountain Creek was obtained fronj COE reports (References 6 and 7). The hydrologic analysis in each was reviewed by the study contractor, and the reports were found to: show a good correlation in peak discharges at common points on Fo~ntain Creek in Colorado Springs for all recurrence intervals. This hydrologic method, utilized in Reference 6 and 7, consists of g4ge station analysis, whereby stream gaging data have been analyzed tal estimate peak flows for the various recurrence intervals. . 12