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<br />sections for each routing reach were developed based on <br />USGS 7.5 minute quadrangle topography. Manning's "n" <br />values were determined based on field inspection and <br />interpretation of aerial photography_ <br /> <br />Haverland Pond was simulated by routing runoff <br />from subbasins SW I, SW II, SW III. and SW IV through <br />the pond using the Modified PuIs option of HEC-l. <br />Approximate stage-discharge and stage-storage <br />characteristics of Haverland Pond were developed from <br />USGS 7.5 minute quadrangle topography. In reality, a <br />small portion of the SW IV sub-basin as delineated does <br />not drain into Haverland Pond, but drains directly <br />through Otis and to the railroad culverts. However, <br />because of the small size of this part of SW IV and <br />because of the minimal peak and time to peak <br />attenuation effects of the pond, we feel that assuming <br />that the entirety of SW IV drains to Haverland Pond is <br />reasonable. Haverland Pond may have greater effects on <br />peak discharges and time to peak. However, these <br />effects cannot currently be further evaluated without <br />more detailed topographic mapping or extensive ground <br />surveys. <br /> <br />I' <br /> <br />A preliminary HEC-l hydrologic analysis with <br />Brunker Lake in place and with a very low assumed <br />infiltration rate (0.01 inches per hour) showed that <br />Brunker Lake would not fill and overflow with the 100- <br />year 6-hour design storm applied to the upstream basin. <br />Brunker Lake and its tributary area were therefore <br />deleted in the final hydrologic analysis. HEC-l output <br />which documents this finding is included in the <br />technical addendum. <br /> <br />2.4.3 Discussion of Results <br /> <br /> <br />The results of the hydrologic analysis were <br />compared with the peak flows developed in eight other <br />studies of basins in the eastern and central plains of <br />Colorado (references 7, 8, 9, 10, 11, 12, 13, and 14). <br />Peak discharge per square mile of basin area was <br />computed for the 10- and 100-year events for all <br />Subbasins analyzed in this study, then compared to 10- <br />and lOO-year peak discharges per square mile developed <br /> <br />11 <br /> <br />I <br />, . <br />; t <br />I, <br />! ;. <br />" <br />" <br />