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results of these computations are tabulated at selected cross sections for each stream segment for which a floodway is computed (Table 1). As shown on the Floodway Map (Exhibit 2), the floodway boundaries were determined at cross sections; between cross sections, the boundaries were interpolated. In cases where the floodway and IOO-year flood boundaries are close together, only the floodway boundary has been shown. The area between the floodway and the boundary of the lOO-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 IOO-year flood more than 1.0 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to flood plain development are shown in Figure 2. I- 100.YEAR FLOOD PLAIN -, FLOODWAY FRINGE FLOOD ELEVATION WHEN CONFINED WITHIN FLOODWAY AREA OF FLOOD PLAIN THAT COULD BE USED FOR DEVELOPMENT BY RAISING GROUND FLOODWAY FLOODWAY FRINGE STREAM CHANNEL D FLOOD ELEVATION BEFORE ENCROACHMENT ON FLOOD PLAIN LINE AS IS THE FLOOD ELEVATION BEFORE ENCROACHMENT. LINE CD IS THE FLOOD ELEVATION AFTER ENCROACHMENT. .SURCHARGE IS NOT TO EXCEED 1.0 FOOT (FIA REQUIREMENT) OR LESSER AMOUNT IF SPECIFIED BY STATE. Figure 2. 5.0 INSURANCE APPLICATION Floodway Schematic In order to establish actuarial insurance rates, the Federal Insurance Administration has developed a proce~s to transform the data from the engineering study into flood insurance criteria. This process includes the determination of reaches, Flood Hazard Factors, and flood insurance zone designations for each flooding source studied in detail affecting the Town of Nunn. 7