How important is data quality in the validity of Bulletin-17-B frequency results? What issues need to be checked?
Data quality is obviously important to validity of the Bulletin-17-B frequency analysis, since the frequency analysis is basically nothing other than a standardized summary of the underlying flood data set. In a critical review of the flood data set, two broad sets of issues need to be considered: 1) relevance of the flood data set (and frequency analysis results) to estimation of future flood risk, and 2) accuracy of the data set as a representation of the flood events that actually occurred in the past. In the first set of issues, factors such as flow regulation by dams, dam failures, stormwater management, effects of development (or reversion to undeveloped conditions) in the flood plain, stream channel improvement or restoration, and the effects of mining, forestry, agriculture, or reclamation from those activities, all have the potential to make all or part of the record unrepresentative of future flood risk. The significance of these factors and the nature of any adjustments that
