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<br />II <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />11 <br /> <br />Depth-Outflow Curve In the Existing HEC-2 "odel <br />The depth-outflow curve for the existing HEC-2 model used in the 1986 study is <br />shown as a dashed line In Figure 3. This curve was generated by running the model <br />several times and Inputting a different peak discharge rate each time. <br /> <br />Sharp-Edged Entrance <br /> <br /> <br />The entrance to the existing railroad culvert is a sharp-edged entrance with an <br /> <br /> <br />entrance loss coefficient of 0.5. The depth-outflow curve for this condition was <br /> <br /> <br />developed in the following manner. A water surface profile was run by hand <br /> <br /> <br />through the existing railroad culvert for a selected peak discharge rate beginning <br /> <br /> <br />with critical depth at the culvert outlet. The profile was then run upstream to the <br /> <br />culvert inlet. <br /> <br />This same procedure was used with several other peak discharge rates. Plotting <br />the various discharges against their respective water surface elevations at the <br /> <br />culvert entrance yielded the curve labeled Ke = 0.5 in Figure 3. <br /> <br />Improved Entrance <br />An improved entrance condition is shown In Figure 4. This inlet has an entrance <br />loss coefficient of 0.2. Water surface profiles were again run by hand similar to <br />that explained above. The resultant depth-outflow curve is labeled Ke = 0.2 In <br />Figure 3. <br />