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<br />) <br /> <br />) <br /> <br />) <br /> <br />The tracing of Curve D is an intermediary step that is not necessary, but <br /> <br />is included here to add clarity to the process. Curve D is then combined <br /> <br />with Curve C to generate Curve E, the damage-frequency curve. The area <br /> <br />under this curve represents expected annual damages. Subsequent <br /> <br />paragraphs will show a sample computation, and will address the <br /> <br />justification for both the procedure used and the conclusion that the area <br /> <br />under the damage-frequency curve represents the expected annual value. <br /> <br /> <br />Sample Computation: Table V-2 displays a comprehensive picture of <br /> <br /> <br />all the relationships used in damage evaluation. This is a standard <br /> <br /> <br />calculation sheet that is designed to provide all relevant information. <br /> <br />For example, if one wanted to know about a particular flood, e.g., the <br /> <br />design flood, by reading across that row, it can be readily observed that <br /> <br />the discharge is 10,000 cfs, the stage is 709.9 feet, the frequency is <br />.6%, or a recurrence interval of 167 years (derived &y dividing 100 by <br />.6), and damages are $418,000. However, only the frequencies and damages, <br /> <br />columns (5) and (7), enter directly into the computation of expected <br /> <br />annual damages. Let us, therefore, concentrate on these columns, and the <br /> <br />mechanics of computing expected annual damage. Column (6) represents the <br /> <br />intervals between frequencies. For example, in the first row, .00135 <br /> <br /> <br />(.135%) - .001 (.1%) - .00035, the first entry in column (6). This is <br /> <br /> <br />done for successive pairs of frequencies, through the entire range. Next, <br /> <br /> <br />we concentrate on column (7). The average damage between successive <br /> <br /> <br />damage estimates is determined and shown in column (8), and results <br /> <br /> <br />entered correspondingly with those in column (6). The entry of $652,200 <br /> <br /> <br />in the first row is the average of $669,800 and $634,600. Corresponding <br /> <br /> <br />values in columns (6) and (8) are then multiplied to give column (9). <br /> <br />V-51 <br />