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<br />. <br /> <br />.0'153 <br /> <br />. <br /> <br />. <br /> <br />31. Flood frequencies. - During the period of continuous record, <br />1921 through 1950, eight floods have exceeded the channel capacity of <br />15,000 cubic feet per second at Trinidad. These flood peaks under exist- <br />ing conditions and with Trinidad Reservoir operating are shown in <br />table 12. In addition to these flood peaks, 13 peak discharges occurred <br />in the category 10,000 to 15,000; and 30 in the category 5,000 to 10,000 <br />cubic feet per second. The fundamental principles used in the computation <br />of flood probabilities are based on procedures outlined in a paper by <br />!eo R. Beard, Office, Chief of Engineers, entitled "Statistical He.thods <br />in Hydrology," dated July 1952, which was distributed with Civil Works <br />Engineer Bulletin 52-24, dated August 1952. The discharge-frequency curve <br />for existing conditions was computed by the anrlual-peak method with the <br />partial-series method being used in the lower discharge range. This curve <br />together with a discharge-frequency Curve of the residual flooding at <br />Trinidad with the project in operation are shown on plate 4. The curve <br />for existing conditions indicates that the channel capacity, 15,000 cubic <br />feet per second at Trinidad, would be eq\mled or exceeded once in four <br />years and the peak discharge of the maximum flood of record, 45,400 cubic <br />feet per second, would be equaled or exceeded once in about 37 years. <br />The curve for regulated conditions indicates that the discharge of 15,000 <br />cubic feet per second would be equaled or exceeded once in 95 years. <br /> <br />26 <br /> <br />APPENDIX B <br /> <br />'",_._', - -- u";_ " ~~'i.'_-_ . . '-.;._ <br /> <br />. <br /> <br />