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<br />II. FLOODPLAIN DELINEA nON <br /> <br />COLORADO WATER CONSERVATION BOARD <br /> <br />1. Computer Backwater Analysis (calculate water surface elevation at each cross-section for <br />the desired storm event, i.e. IOO-year event) <br /> <br />2. Flood Profile (using stream centerline stationing. connect water surface elevations at cross- <br />sections to show continuous elevations along entire stream reach being studied) <br /> <br />3. Prepare Flood Contour Plotting Table (for each increment of ground elevation, i.e, every 2 <br />feet, find the water surface elevation on the profile and then find the stream centerline <br />station that corresponds to that water surface elevation) <br /> <br />4. Plot Water Surface "Wiggly Lines" on Contour Map (at appropriate stream centerline <br />stations draw wiggly lines for water surface; lines must be perpendicular to direction of <br />flood flow; continue water surface lines until they intersect corresponding ground elevation <br />contour) <br /> <br />5, Delineate Floodplain Boundary to Create Floodplain Mapping (connect edge of floodplain <br />at each water surface contour, noting islands, "levees" that might fail, bridges, culverts and <br />other unusual features) <br /> <br />6, Field Verification (take draft floodplain maps to the fIeld and review them to assure that <br />they would make sense to local residents and other interested parties; make corrections if <br />necessary) <br />