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different methods and did not rely on the approximate comparison of measured water <br />surfaces. <br />Manning's Equation Predictions <br />Mannings equation required as much computation time as HECRAS but provided less <br />information and was much less reliable because of the slope assumptions and now ratio <br />computation needed for this method. This was the only method that used an approximate <br />ratio to estimate flow conveyed in the WC channel, and the ratio did not consistently <br />provide good results as shown by Manning's predicted change at sites 4 and 5 in the <br />Table (pink blocks where the water surface went down when it should have gone up, or <br />The Mannings equation computations were less reliable when the transects had fewer <br />points. Transects with 7 to 10 points, in comparison to 30 or 40 points, had more <br />tendency to plot in a triangular shape. The Mannings equation method worked better with <br />a rectangular shape. This could be avoided by not using the rectangular assumption and <br />solving for multiple variables (area and perimeter) using an iterative process spreadsheet <br />or simple program. But this additional effort was not justified by results since a ratio was <br />still needed and the ratio was not reliable in 3 of the 14 cases considered (see Overton <br />and Kearney comparisons in the table). <br />Staff Gage Method <br />The staff gage method requires no computation time. If the WC is sited in a cross section <br />• similar to the cross section at the gage, the water surface prediction is good. This method <br />does contain errors when there are split flows and different width to depth ratios. <br />HECRAS Method <br />HECRAS took more time to reduce but provides the most detailed response to multiple <br />variables and the most reliable response, if there is a relatively similar cross section in the <br />model at the Whooping Crane site. This method relies on the least number of <br />assumptions, provides an exact solution, and provides the most detailed consideration of <br />physical processes. <br />This method will be less accurate at sites that are not well represented by adjacent cross <br />sections. There is a gap in cross section data between river mile 210.6 and 219.8. <br />Once the transect data is input, multiple flows can be quickly analyzed along with <br />conditions at alternative sites (estimates at alternative locations are dependent on the <br />cross sections available). Considerations of travel time can be incorporated into the <br />analysis of the change in water surface if real time data (15 min intervals) is available to <br />enter in HECRAS. <br />Summary of Phase I Whooping Crane Data Analysis November 6, 2007 <br />6 <br />