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<br />. <br /> <br />'. <br /> <br />. <br /> <br />0159 <br />. <br /> <br />PROJECT DESIGN REG UIREMENTS <br /> <br />37. Standard project flood. - Based on the storm transposition <br />described previously, it was estimated that only the maximum 6-hour <br /> <br />rainfall would have produced appreciable runoff. Using a minimum in- <br /> <br />filtration rate of 0.49 inch per hour, the standard project flood was <br /> <br />computed by applying the rainfall excess to the adopted unit hydro graphs <br /> <br />for both Trinidad and Trinidad dam site. The standard project flood at <br /> <br />Trinidad thus derived would have an estimated peak discharge of <br /> <br />106,000 cubic fect per second and a volume of 67,800 acre-feet, or <br /> <br />1.79 inches of runoff over the 710 square miles of contributing drain- <br /> <br />age area. <br /> <br />38. The maximum 6-hour rainfall of the standard project storm <br /> <br />above Trinidad dam site would amount to 4.66 inches with a maximum I-hour <br /> <br />rainfall of 1.33 inches. This storm would cause a flood at the Trinidad <br /> <br />dam site with a peak discharge of 99,000 cubic feet per second and a <br /> <br />volume of 57,900 acre-feet or 1.77 inches of runoff from the 613 square <br /> <br />miles of contributing drainage area. The intervening area between the <br /> <br />dam site and Trinidad gage would pro duce a flood from the standard proj- <br /> <br />ect storm with a peak of about 28,000 cubic feet per second and a volume <br /> <br /> <br />of about 9,900 acre-feet at Trinidad gage. The peak flow from this inter- <br /> <br />vening area would occur about three hours prior to the peak flow at the <br /> <br />dam site. During the summer months, flow at Trinidad averages only about <br /> <br />150 cubic feet per second for long periods of time. For this reason base <br /> <br />flow has been disregarded in computing the standard project flood. The <br /> <br />standard project flood hydro graph with hyetograph, mass rainfall curve, <br />and isohyetal map are shown on plate 5. A graphical comparison of the <br /> <br />standard pr.oject flood peak and the envelope curve of maximum peak dis- <br /> <br />charge of record fOr areas within the Albuquerque District is shown on <br /> <br />plate 6. <br /> <br />32 <br /> <br />APPENDIX B <br /> <br />, <br /> <br />~'_- ____-':.",.; "L. ~__~i> <br /> <br />. <br /> <br />':'-,-;i" <br /> <br />