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The results of these computations were tabulated at selected cross sections for each stream segment for which a floodway was computed (Table 2). As shown on the Flood Boundary and Floodway Map (Exhibit 2), the floodway widths were determined at cross sections; between cross sections, the boundaries were interpolated. In cases where the boundaries of the floodway and the 100-year flood are either close together or collinear, only the floodway boundary has been shown. The area between the floodway and the boundary of the 100-year flood is termed the floodway fringe. The floodway fringe thus encompasses the portion of the flood plain that could be completely obstructed without increasing the water-surface elevation of the 100-year flood more than 1.0 foot at any point. Typical relation- ships between the floodway and the floodway fringe and their signif- icance to flood plain development are shown in Figure 9. \- 100.VEAR FLOOD PLAIN ~ I FLOODWAY FRINGE FLOODWAV FLOCCWA V FRINGE STREAM CHANNEL FLOOD ELEVATION WHEN CONFINED WITHIN FLOOOWAY AREA OF FLOCD PLAIN THAT COULD BE USED FOR DEVELOPMENT BY RAISING GROUND FLOOD ELEVATION BEFORE ENCROACHMENT ON FLOOD PLAIN LINE AS IS THE FLOOD ELEVATION BEFORE ENCROACHMENT. LINE CD IS THE FLOOD ELEVATION AFTER ENCROACHMENT. .SURCHARGE ISNOTTOEXCEED 1.0 FOOT (FEMA REQUIREMENT) OR LESSER AMOUNT IF SPECIFIED BY STATE. Figure 9. Floodway Schematic 5.0 INSURANCE APPLICATION In order to establish actuarial insurance rates, the Federal Emergency Management Agency has developed a process to transform the data from the engineering study into flood insurance criteria. This process includes 19