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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />111-3 <br /> <br />The flood routing for the Phase B analysis consisted of routing <br />the future development hydrographs through the improved drainageway <br />as proposed by the selected alternative plan (see Chapter I, Intro- <br />duction: Selected Alternative, for description of the alternative <br />plans). These results of the routing were then used as design flows <br />for the proposed drainageway improvements. Hydrographs were developed <br />for key design locations and are presented in Figures 111-2 through <br />111-9. Both the inflow and discharge hydrographs are presented for <br />Hidden Lake, Lake Sangraco, Bates Lake and the proposed detention <br />pond in the Bates Lake basin, as well as the maximum detained volume. <br />The hydrographs presented are based upon the completion of all <br />upstream projects. <br />D. Floodway Determination <br />One of the key factors for success in the administration of a <br />floodplain regulation is the subdividing of the floodplain into a <br />floodway area and a flood storage area. The floodway is defined as <br />that area required for the reasonable passage or conveyance of the <br />100 year flood which is characterized by hazardous and significant <br />depths and velocities. The floodway area of a floodplain would have <br />strict regulations governing its use. The flood storage area is <br />defined as the fringe portion of the floodplain in which flows are <br />characterized by shallow depths and low velocities. This area has <br />less stringent regulations and is developable under certain conditions. <br />