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Appendix D — SOP for Stream Flow Measurement — Hansen Project 5 <br />3. Measure and record the flume length to the nearest 0.01 feet. <br />4. Record the time and date of the site visit. <br />5. Use the staff gage to measure and record the stage in the upstream section to the nearest 0.02 feet. <br />6. While recording the upstream stage, check downstream staff gauge and confirm reading is at least one - <br />half the value of the upstream staff gage reading. <br />7. Calculate discharge as described below. <br />8. Record the calculated discharge. <br />3.1.3 Discharge Calculations <br />Discharge Calculations for the Parshall Flume <br />Discharge calculations for the Parshall Flume assume free -flow discharge conditions exist. Discharge (Q) can <br />be calculated using the form: <br />where: <br />Q = Chan <br />ha = measuring head (ft) <br />Q = discharge (ft3 /s) <br />C and n = constants (see Table 1) <br />Note that approximate values of discharge for heads other than those shown may be found by direct <br />interpolation in Table 1. If submerged flow conditions exist, refer to Chapter 8 of the United States Bureau of <br />Reclamation Water Measurement Manual (USBR, 1997). <br />4153A.140129 Whetstone Associates <br />