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<br />30.0 <br /> <br />25.0 - <br /> <br /> 20.0 <br />~ <br />t: <br />0 15.0 " <br />:;::; <br />III <br />> <br />.. <br />W <br /> 10.0 " <br /> <br />"' <br />, <br /> <br />//// <br /> <br />" ---_n_ ~(iJ~t::)- <br /> <br />/ <br />/ <br />/ <br /> <br />5.0 <br /> <br />00 - <br />0.0 <br /> <br />20.0 <br /> <br />40.0 <br /> <br />60.0 <br /> <br />80.0 <br /> <br />100.0 <br /> <br />120.0 <br /> <br />140.0 <br /> <br />160.0 <br /> <br />Stationing (ft) <br /> <br />Figure 6 - Possible subdivision of the channel cross-section at Geary Creek tributary into more "prismatic" <br />sections. Section 1 is a flood bar and Section 2 includes the main channel. The dashed line indicates the water <br /> <br />level. <br /> <br />3.3 Flood frequency analysis <br /> <br />Several methods exist to determine the frequency relationship of uncertain phenomena. In an <br />effort to remain consistent with previous analyses and standard practice, the recommended <br />methods outlined in the Interagency Advisory Committee on Water Data (IACWD) Bulletin 17B <br />are used to develop the flood frequency. <br /> <br />Bulletin 17B was developed to provide a standardized and consistent method to analyze flood <br />data in the United States. It provides a method for handling high and low outliers as well as <br />incorporating historic data. The sample statistics, once adjusted for outliers, are weighted by the <br />length of the historic record. The final distribution is derived once the historically weighted <br />statistics are adjusted for censored data. This procedure uses the log-Pearson III probability <br />distribution. <br /> <br />The process outlined in Bulletin 17B to account for censored data is recommended for data sets <br />with less than 25 percent censored data. Censored data refers to flood flows that are either less <br />than the minimum flow or greater than the maximum flow that the gage is capable of detecting. <br />The sites in this study only contain values that are censored from below and are in excess of the <br /> <br />8 <br /> <br />/ <br />t/ <br /> <br />\ <br />