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<br />The flood profiles presented in this study are based on flow through <br />unobstructed hydraulic structures such as bridges, dikes, dams and levees. <br />Therefore the results should be considered valid only if these structures <br />do not fail and remain unobstructed. A detailed description of the <br />hydrauliC analysis is included in the TeChnical Addendum. <br /> <br />INTERPRETATION AND USE OF REPORT DATA <br /> <br />Flood Frequency and Discharge <br />The 10-, 50-, 100-, and500-year floods were used as the flood frequencies <br />forthisfloodplainana1ysis. Thus, the data developed in this report will <br />be compat1ble not only for regulation purposes, andK.B.l041designations <br />but also for Federal Emergency Management Agency flood insurance rate <br />studies. Data prepared in this study will be used 1n the Federal Flood <br />Insurance study. <br /> <br />These various flood events have an averageoccuranceofonce 1n the number <br />of years as indicated, For example, the 100-year flood occurs, on the <br />average, once in a 100yearperiod,and has a one percent chance of being <br />equaled or exceeded in any given year. <br />The particular uses for the various flood events in addition to those <br />stated above areas follows: <br /> <br />10-year and 50-year flood events Information regarding these more <br />frequent floods is especially useful for future engineering studies and <br />land use planning purposes related to minor road systems. minor channel <br />improvements, the location of parks and recreational facilities, agri- <br />cultural lands, and appurtenant structures. For structures and uses of <br />this type on the smaller tributaries and in areas where the high riSk of <br />structural fallure is economically feasible and the hazard to life and <br />property i s none~i stent, the use of the more frequent floods as des1gn <br />criterlamaybeconsidered. <br />100-year flood event nThI' lOO-year flood event may also be used for <br />engineering design purposes where a lower risk of failure than th<:>10- or <br />50-year flood is desired. However, the most fmportant use of the 100-year <br />flood event l1es in floodplaindesigMdtion an(\land use regulation as set <br />forth in the state sta tutes. ,t,e Sta te of ColoradC consi dl'r~ t\'\e loo-year <br />frequency flood as the flood event to be used indesignir'lg and protecting <br />structures and dwellings for hurnanoccupatlon. Therefore, all floodplain <br />regulations are based upon thelOO-yearflood, Also, the area which would <br />be inundated by the 100-year flood may be delineat('li as an area of state <br />interest as set forth in H.B. 1041 d the state's land use bill. <br /> <br />SOO~year flood event __ The SOO-year flood event is useful 1n maUng the <br />pUblic aware that floods larger than the lOG-year flood can and do occur. <br />Just because a person 1 s 1 i vi ng above the lOO~year fl ood boundary does not <br />mean that he , s compl etely sa fe frOlll f1 Qod i ng. The 5GG-:;~Jr fl.::od C~'(!;:t <br />can a1so be used for regulating high risk developments with thf' floodplain <br />such as nuclear power plants, or tM storage or manufacture of tox1c or <br />e~ p1 osi ve lllaterial s. <br />Table 5-1 lists the discharge anI! water sudace elpvat10ns for the 10-, <br />50-,100- and500-year flood events at selected reference points, for the <br />reach of Arkansas River from Minnequa Dam to approximately Colorado Highway <br />115 (Appendi~ ll. Table 5-11 11 sts the discharges and water surface <br /> <br />21 <br /> <br />22 <br />