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<br />It is possible to standardize many elements of flood frequency <br />analysis. This guide describes each major element of the process of <br />defining the flood potential at a specific location in terms of peak <br />discharge and exceedance probability. Use is confined to stations where <br />available records are adequate to warrant statistical analysis of the <br />data. Special situations may require other approaches. In those cases <br />where the procedures of this guide are not followed, deviations must be <br />supported by appropriate study and accompanied by a comparison of results <br />using the recommended procedures. <br />As a further means of achieving consistency and improving results, <br />the Work Group recommends that studies be coordinated when more than one <br />analyst is working currently on data for the same location. This recom- <br />mendation holds particularly when defining exceedance probabilities for <br />rare events, where this guide allows more latitude. <br />Flood records are limited. As more years of record become available <br />at each location, the determination of flood potential may change. <br />Thus, an estimate may be outdated a few years after it is made. Addi- <br />tional flood data alone may be sufficient reason for a fresh assessment <br />of the flood potential. When making a new assessment, the analyst <br />should incorporate in his study a review of earlier estimates. Where <br />differences appear, they should be acknowledged and explained. <br /> <br />I I. Summary <br /> <br />This guide describes the data and procedures for computing flood <br />flow frequency curves where systematic stream gaging records of sufficient <br />length (at least 10 years) to warrant statistical analysis are available <br />as the basis for the determation. The procedures do not cover watersheds <br />where flood flows are appreciably altered by reservoir regulation or <br />where the possib.ility of unusual events, such as dam failures, must be <br />considered. The guide was specifically developed for the treatment of <br />annual flood peak discharge. It is recognized that the same techniques <br />could also be used to treat other hydrologic elements, such as flood <br />volumes. Such applications, however, were not evaluated and are not <br />intended. <br /> <br />2 <br />