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<br />001816 <br /> <br />snowmelt to freeze-up which is approximately from early April to the end of October. Because <br />flow duration curves require complete years of record, the missing daily mean flows were <br />estimated. The second issue--the representativeness of the existing record--also arose at the <br />Forest Service stations where the flow record may not represent the distribution of flows <br />associated with climatic variation over the long term. To estimate distributions over the long- <br />term, the records at these stations were extended. Appendix 3 explains the extension procedure <br />in more detail. <br /> <br />Daily mean flows at each Forest Service station were related to a nearby continuously <br />operated "base-station" having a longer discharge record. A relationship was developed using <br />pairs of daily mean flows from the "concurrent" period (the period during which data were <br />available from both stations). This relationship was used to estimate missing values and extend <br />the Forest Service records using base-station daily mean flows. The technique (Moog et al,. <br />manuscript) is derived from a method outlined by Hirsch (1982), Maintenance Of Variance <br />Extension (MOVE. I ). Although each daily mean flow at the Forest Service station is estimated <br />as a function of the corresponding base-station flow, the focus is not to accurately predict each <br />daily mean flow, but on correctly estimating the distribution of Forest Service station discharges. <br />Climatic information contained in the base-station record is thereby transferred to the <br />distributional information at the Forest Service station. <br /> <br />When choosing a base-station for a given Forest Service station, attempts were made to <br />match the basins by size, proximity, and mean elevation in the expectation that hydrological <br />responses will be similar. However, the concept of hydrological similarity is complex and <br />matching easily measurable features does not always ensure that scatterplots of the concurrent <br />records produce linear point patterns with constant variance. In addition, if only a few stations <br />are nearby, a good match may not be possible. Therefore, the best available base-stations may <br />have concurrent data sets whose scatterplots have curved point patterns and uneven variation <br />over the range of flows at the base-station. <br /> <br />This situation can be alleviated by transforming the discharges from one or both stations <br />to more closely approximate a linear function-constant variance relationship. The MOVE.! <br />technique was applied to these transformed data sets, the records filled in and extended, and the <br />augmented records back-transformed to original units. Values measured at the Forest Service <br />stations during the concurrent periods were combined with the estimated fill-in and extended <br />flows. <br /> <br />Table 3 describes the water years of record, the associated base stations and their periods <br />of record, and the total number of base-station years of record at the claim sites. Table 4 <br />describes the corresponding data at the fluvial process study sites. In some cases, the actual <br />record length of the Forest Service station was greater than that indicated but was not used <br />because of concerns regarding data quality or measurement methodology. <br /> <br />United States' Expert Report Disclosing Melhodologies for Quantification of Organic Ad Claims Consolidated Subcase No, 63.25243 <br /> <br />26 <br />