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<br />. <br /> <br />3' Relationhip to Control Gage <br /> <br />~.-. <br />-.J <br />W <br />-.l <br /> <br />The segment of stream where cross-section measurements are <br />made need not include the location of the gage used for <br />di scharge records, but may be ei ther upstream or down- <br />stream, even a considerable distance from the gage. <br /> <br />Cross-sections at the gage, although generally available, <br />are not generally useful for stream simulation purposes, <br />since gage locations are selected for flow-measurement <br />purposes and tend to be atypical of normal streambed <br />configuration. It is important, however, to be sure that <br />no significant inflows or diversions occur between the <br />measurement segment and the gage. <br /> <br />. <br /> <br />4' Cross-section Establishment and Measurements <br /> <br />Using a hand-compass, the cross"section azimuth is deter- <br /> <br /> <br />mi ned and four stakes are sighted in on thi s 1 i ne. The <br /> <br /> <br />observer stands at the top of the lo....er bank, where over- <br /> <br /> <br />flo.... would first occur; this is staked as point A. A <br /> <br /> <br />stake is placed at the water's edge nearest A; this is <br /> <br />point B. The third stake (C) is put at the opposite <br />water's edge, and the fourth (D) is located on the oppo- <br />site bank on a level with A. <br /> <br />. <br /> <br />Line AD represents water surface at bank-full capacity; <br /> <br /> <br />BC, the water surface at time of measurement (discharge at <br /> <br /> <br />that time is ascertained later from USGS gage records). <br /> <br />25 <br />