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3.1 Hydrologic Analyses Hydrologic analyses were carried out to establish the peak discharge- frequency relationships for floods of thp selected recurrpnc(' int('r- val s for pach stream studied in detail and to comparl' rpsu1ts lwtwl'pn prev i ous reports for the fl ood i ng sources undl'r s turly here, A regional relationship of basin area to peak discharge was used for the Arkansas River. Gaging stations located within the upper Arkansas basin were used to establish this regional relationship, The method developed by the U.S. Water Resources Council (Reference 4) was used to determine the floodflow-frequency relationship, based on a log-Pearson Type II I oi stribution for each se1 ected gaging station. The annual peak discharges were obtained from U,S, Geo10Q- ica1 Survey Water-Supply Paper Nos. 1681, 1921, and 3721 (References 2, 5, and 6, respectively) and from Water Resources Data for Colorado (Reference 7l. Regional relationships of basin area to peak dis- charge were determined for the 10-, 50-. 100-, and 500-year fl oods. These discharges were then compared to the discharges obtained from the Corps of Engineers' study at Florence, Colorado (Reference 8), The discharges obtained in the regional analysis fell within the 90~, confidence limits of the discharges in the Florence report and there- fore the hydrologic analysis as presented in the Florence Flood Plain Information Report was adopted for use in estimating the flood bound- aries for the Arkansas River. The discharges for the tributaries in Canon City were obtained using the pub1 ication "Procedures for Deter- Mining Peak Flows in Colorado" (Reference 9). Thi s method was used in the Colorado Water Conservation Board report, "Flood Plain Information Re ort for Northeast Canon Draina e," (Reference 10), e y ro OglC ana YS1S ln t e ort east anon Drainage Report was adopted for thi s Flood I nsurance Study. Ra i nfa 11 amounts for Forked Gulch, Sand Creek and Southeast Canon Drainage were obtained from National Oceanic and Atmospheric Administration Atlas 2, Precipi- tation-Frequency Atlas of the Western United States (Reference 11), Peak discharges for each flooding source are presented in Table 2. 7