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<br />!I <br />il <br />II <br />I <br />I <br />I <br />I <br />I <br />I. <br /> <br />, <br /> <br />II <br />II <br /> <br />I <br />'I <br />I <br />I <br />I <br />I <br />,I <br />il <br />I <br />'I <br /> <br />The North Poudre Ditch would intercept further excess flows <br /> <br />at the confluence of Park Creek and Spring Gulch. This <br /> <br />information is of little use, however, since we have no <br /> <br />conclusive observations related to flooding in this part of <br /> <br />the basin. <br /> <br />Therefore, only qualitative observations could be used to adjust <br /> <br />flows upstream of Douglas Reservoir. The initial results at <br /> <br />Douglas Reservoir for a 100-year event showed a peak outflow of <br /> <br />400-cfs, ignoring any interception at the irrigation canals. <br /> <br />This flow magnitude is consistent with what would be expected <br /> <br />from simple observation at the spillway. However, this peak <br /> <br />outflow was substantially different from the IOO-year peak <br /> <br />butflow of 1,700-cfs reported in the Flood Insurance Study <br /> <br />Hydrology Report. Because the difference was so large and <br /> <br />because permeability rates seemed unusually high to be used for <br /> <br />infiltration in the upper basin, loss rates were determined by <br /> <br />a second method, using the Soil Conservation Service's curve <br /> <br />number tables for a 100-year event. Assuming the U. S. Army <br />Corps of Engineers' depression storage of 0.3" to be good, an <br />infiltration rate was determined. This constant value was then <br /> <br />input into the SW~~1 model in place of the permeability range, <br /> <br />and the model was rerun. Peak outflows from Douglas Reservoir <br /> <br />for the 100-year event remained the same. This method amounts <br /> <br />, ,';'''~~', :.(;~: ~ <br />,~~;,~~}~~~~. <br />