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1. Table-5,"FloodFrequency,ElevationandDischargeData." CHAPTER II INTERPRETATIONANDUSE01'REPORTDATA 2. Flooded Area Plates 1 through 10. 3. Flood Profiles on PIaas 11 through 20. A. Flood Frequency and Di.charge 4. Typical Cross Sections On Plates 21 and 22. This report was prepared to be compatible with the H.B. 1041 designation, Federal Emergency Management Agency (FEMA) flood insurance rate studie., and can be adopted by local governments for regulation purposes. The 5-, 10-, 50-, 100-, and 500-year frequency flood events were used in the analysi.. These flood event probabilities..ay aIso be represented as having a2 0,10, 2, l,andO.2percentchanceofbeingequaledOrexceededinanyonegiven ycar, respectively. The flood profiles may be used tn areas where controversy arises over the 100-year flood boundary shown on the flooded area plates. Since the flood profiles give the elevation at a specific point on the reference line, the high water elevations can be conveyed to the ground. A number of control markers are in place along the study reach which can be used for this purpose. The markers consiat of 3-inch diameter brass caps set in concrete or a cap and rebar which are stamped with appropriate identi- fication. The pertinent information and locations of the control markers are listed in Table-I. Further verification and more specific informat.on concerning these control markers should be ohtaincd frOm the offices (see paEe vii) distributing the reports prior to any actual surveys. The mo.t important use of the lOa-year flood data is for the description of the floodplain and it. land USe regulation. The ColoradO State ststutes consider the 100-year flood as the flood event to be used in designing and protecting all buildings and struttures to be used for human occupancy. This level of flood protection has teceived nationwide acceptante. Information concerning more frequent flood events is provided to allow a,sess~ent of the risks of flood d~~ge3 Guring lesser floods. Minor roads, recreation facilities, and livestock structures may often be designed based on floods smaller than the 100-year flood. A higher riSk of damage may be acceptable for the desi~n of these types of facilities. C. Flooded Areas B. Flood Elevations In Colorado the lOa-year flood has been .elected to delineate and regulate floodplains. Therefore, the flooded area maps show the 100-year floodplain boundary for Dry Creek No.1. The mappin~ has a 2-foot contour interval and scale of I-inch equal to 400 feet. If needed, the floodplains produced by other frequency floods could be readily delineated on these maps using the inrorm..~i,," in Tabh-5. Th~ no"d~u areas for Dry Creek No.1 .Ire presented on Plates I through 10. Water surface elevations for the S-, 10-, 50-, 100-, and 500-year flood for Dry Creek No.1 can be found in four loeations within this report. These loeatioos are as follows: The 100-year flondplain. as delineated on the flooded area maps, meets the requirements of House Bill 1041. Upon official approval of this report by the Colorado Water Conservation Eoard, the area outlined Oil the Olaps will be designated 3S flOOdplain and the local officials may regulate it accordin~ly. 7 8