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<br />. <br /> <br />. <br /> <br />. <br /> <br />Roughness Coefficients <br /> <br />Manning's roughness coefficients were determined from a combination of field investigations <br />and the use of orthophotos in areas where access was difficult to obtain, For the natural channel, a <br />Manning's base value of 0,035 was selected and adjusted as follows, <br /> <br />The Los Pinos River meanders throughout the entire study reach, To account for the <br />meandering between cross sections, a correction factor was applied to the channel Manning's base <br />value, Chow (1959) suggests correction factors of 1.00 for minor meandering, 1.15 for appreciable <br />meandering, and 1.30 for severe meandering, For this reach, values ranging between 1.00 and 1.15 <br />were utilized resulting in channel Manning's coefficients ranging from 0,035 to 0,043, <br /> <br />The Manning's roughness coefficients used in the model for the overbanks ranged from 0,05 <br />to 0, 15, The principal overbank composition for this reach included field crops and pastures, <br />light/medium brush, and trees, A minimum Manning's coefficient of 0,05 was used throughout this <br />reach, with higher values used as noted during field investigations or by inspection of orthophotos, <br />Table 4 displays the range and conditions of Manning's "n" values used for this study, <br /> <br /> TABLE 4 <br /> MANNING'S ROUGHNESS COEFFICIENTS <br /> LAND TYPE MANNING'S "n" VALUE <br />Los Pmos River 0.035 - 0.043 <br />Overbanks <br />Cultivated Areas, Heavy Weeds, Scattered Brush 0.05 - 0.06 <br />Dense Brush 007 - 0.08 <br />T fees 0.09 - 0.15 <br />Urban Areas 0,10 <br /> <br />Bridges <br /> <br />There are 4 bridges crossing this reach of the Los Pinos River. Bridge information was <br />compiled from field inspections by the U.S, Army Corps of Engineers and Resource Technology. <br />Bear Dance bridge and the State Route 151 bridge are both located in Ignacio, the La Plata County <br />Road 322 bridge is located approximately 1,5 miles upstream of La Boca, and the abandoned railroad <br />bridge is located at La Boca, This abandoned Denver & Rio Grande Western Railroad bridge is still <br />used by local vehicle travel. <br /> <br />The maximum bridge hydraulic capacity is defined as the peak flow that can pass under the <br />13 <br />