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Appendix D — SOP for Stream Flow Measurement — Hansen Project 3 <br />pattern of the river and elimination of most of the sag, through support or tension, are recommended for <br />improved accuracy. <br />Headset. A headset attaches to an electronic connection at the upper end of the wading rod. The hydrographer <br />wears this headset to listen to audible clicking sounds which are produced when a rotating gear in the current <br />meter makes contact with a thin wire ( "cat's whisker ") in the contact chamber. The rotating gear contacts the <br />cat's whisker once each time the series of cups on the meter revolves one complete turn. The number of <br />rotations are counted and timed. The first click is counted as zero. The relationship between rotations and time <br />is the point velocity. Velocities as a function of time are listed on a velocity chart, which is kept in the current - <br />meter carrying case. <br />Stop Watch. A stop watch is used to measure time during which velocity is measured at each point in the <br />cross section. Velocity at each point is measured for a period greater than or equal to 40 seconds and less than <br />or equal to 70 seconds. <br />Staff Gage. Each location where the velocity-area method will be consistently applied will be equipped with <br />standard USGS vertical staff gages. <br />The staff gages will be used to measure gage height to the nearest 0.02 feet. <br />2.4 Materials Required for Indirect Methods <br />The following items may be used in field work for indirect discharge measurements: <br />Survey: <br />• <br />Transit <br />• <br />Tripod <br />• <br />Level rods <br />• <br />Level -rod level <br />• <br />Hand level <br />• <br />Engineer's folding rule or 6 -ft. steel tape <br />• <br />Fieldbook and field data sheets <br />• <br />Stakes <br />• <br />Hatchet or axe <br />• <br />Machete, brush cutter <br />• <br />Marking equipment (nails, tape, crayon, paint, chisel) <br />• <br />Field drafting equipment (triangles and protractors) <br />Cross section: <br />• Tagline <br />• Wading rod (or level rod) <br />• Boots <br />• Waders <br />• Metallic tape <br />• Sounding line, weight, reel <br />Miscellaneous: <br />• Camera <br />• Stream- gaging equipment <br />• Backpack <br />• Rope, string <br />• Two -way radios <br />• 3 -ft. carpenter's level <br />4153A.140129 Whetstone Associates <br />