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<br />All rod readings should be carefully labeled for what they represent. Descriptions <br />would include labels like "left high water mark", "top of left bank", "left edge of water" etc. <br />The use of walkie-talkie allows the rod person to relate the description to the person <br />taking notes. <br /> <br />3.3.4 PHOTOGRAPHS - Photographs are valuable in determining and later <br />verifying estimates of Manning's "n". The following photographs should be taken before <br />the survey is completed and the stakes & flagging removed. <br /> <br />1) Each cross section looking across from both banks. <br />2) Each channel reach looking upstream and downstream from each cross section. <br />3) The channel reach immediately upstream of the most upstream cross section. <br />4) The channel reach immediately downstream of the furthest downstream cross <br />section. <br />5) A distant photograph of the entire slope area reach. <br />6) Any unusual features or high water marks. <br /> <br />3.3.5 ASSESSMENT OF MANNING'S "n" - An initial estimate of the <br />roughness coefficients should be made during the survey. Roughness coefficients will <br />be needed for each cross section reach for the channel, the left overbank and the right <br />overbank. The estimates should be made by an experienced member of the survey <br />party. Good judgement in the field is worth much more than second guessing in the <br />office several weeks later. <br /> <br />4. REFINING THE FIELD NOTES. <br /> <br />Before the computation of discharge can begin, the survey data must be refined into <br />acceptable input. The following steps accomplish this: <br /> <br />4.1 WORK UP THE SURVEY NOTES AND HAVE THEM CHECKED. - Stadia are <br />converted to distances and rod readings to elevations in this step. <br /> <br />4.2 DRAW A PLAN VIEW OF THE SURVEY USING THE DISTANCES AND <br />AZIMUTHS TO SCALE. - Make the drawing sufficiently large, so that the stream channel, <br />high water marks and the position of distance between cross sections can be drawn and <br />labeled. <br /> <br />4.3 DRAW THE CROSS SECTIONS ON GRAPH PAPER. - Keep the horizontal <br />and vertical scales the same, so that the cross section flow areas can be digitized or <br />planimetered. <br /> <br />4.4 DETERMINE THE MANNING'S "n" VALUES FOR EACH REACH. - The <br />photographs and remarks made during the survey can be used to check the "n" values <br /> <br />1-6 <br />