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~.~ <br />~ ~ <br />performed by the same person using the same stopwatch. All field <br />data were gathered by ilr. James L. Piachin, Radian engineer/hydro- <br />logist, and Mr. Charles E. Keliher, retired U.S. Geological Survey <br />hydrologist. <br />3.2 Channel Storage Adjustments <br />To monitor river stage during the investigation, a ~ <br />Stevens digital recording stream gage was temporarily installed <br />at the S.H. 13 bridge. The gage records river stage to the near- <br />est hundredth of a foot and was adjusted to record every five <br />minutes over the four-day period. These data were correlated ~ <br />with the discharge measurements to define a flow rating curve ' <br />for the range of gage heights encountered during the study. <br />This rating curve is presented in Appendix C. <br />• Average velocity of the river caas estimated so that i' <br />time of travel through the v.ti mile ~ea::h could be calculated. <br />Time of travel was later considered with the recorded gage data !' <br />to determine if a..y changes in channel storage needed to be ~. <br />taken into account in evaluating the discharge measurements. <br />Channel storage change is the volume of water that is <br />being removed from or added to a particular stream segment over <br />a period of time. It is determined from the surface area of <br />that segment and the change in river stage due to upstream con- <br />ditions over the period of interest. Channel storage changes <br />were estimated based on the recording gage data and average <br />river width. <br />3.3 Evapotranspiration <br />Two instream evaporation pans were installed in the <br />i reach of interest (see Figure 2-1). Eacl: pan consisted of a plas- <br />tic bucket insez~ted into a plycaood collar secured to an inner <br />3-2 <br />