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<br />reflects the difference in the infiltration assumptions in CUHP versus those used in <br /> <br />HEC-1. <br /> <br />B. RAINFALL ONLY - WITH DEVELOPMENT <br />1. Introduction <br />To estimate the effect that new developments may have on flow adjacentto and through the <br />development, an example development was analyzed, A preliminary plan for the Top of the <br />Mill development was received from the City, The proposed development, which is located <br />at the south end of Mill Street, was then coded into the model. <br /> <br />When buildings are placed in the flow path offlowing water, the buildings reduce the width <br />available to pass the flow and cause the water surface elevation to increase, This increase in <br />water surface elevation may be localized and only effect the area where the buildings are <br />located, but this increase in water surface elevation can also expand and effect areas <br />upstream of the buildings, downstream of the buildings, and adjacent to the buildings, <br /> <br />FLO-2D allows the flow area through designated nodes to be reduced. From the plans of the <br /> <br /> <br />Top of the Mill development, the width of the lots is approximately 400 feet and the width <br /> <br /> <br />of the houses is about 320 feet in the direction of flow, Based on these values,. the width <br /> <br /> <br />available to pass flow through the nodes associated with this proposed development were <br /> <br /> <br />reduced by 80%, The area available to store water and allow infiltration was also reduced. <br /> <br />2, Methodology <br /> <br /> <br />The methodology used to estimate the maximum depth of flow with the development <br /> <br /> <br />constructed was the same as previously discussed, No mitigation measures have been <br /> <br /> <br />assumed to be constructed. <br /> <br />3. Results <br /> <br /> <br />By accounting for the effect of the buildings in the proposed development, the model shows <br /> <br /> <br />that the maximum water depth increases by 4 feet at some locations. Due to the <br /> <br /> <br />approximations used in the data and modeling assumptions, this increase should be <br /> <br />16 <br /> <br />11 <br />j' <br /> <br />, <br />, <br />I <br />I <br />I <br /> <br />-J.'... <br />---- -- <br />