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the floodway and the boundary of the 100-Year flood is termed the floodway fringe. The floodway fringe thus encompasses the portion of the floodplain 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 relationships between the floodway and floodway fringe and their significance to floodplain development are .shown in Figure 10. 5.0 INSURANCE APPLICATION For flood insurance rating purposes, flood are assigned to a community based on the analyses. These zones are as follows: insurance zone des ignat ions results of the engineering Zone AE Zone AE is the flood insurance rate zone that corresponds to the 100-year floodplains that are determined in the Flood Insurance Study by detailed methods. Whole-foot base flood elevationsderived from the detailed hydraulic analyses are shown at selected intervals within this zone. .Zone X Zone X is the flood insurance rate zone that corresponds to areas outside the 500-year floodplain, areas within the 500-year flood- plain, areas of 100-year flooding where average depths are less than 1 foot, areas of lOO-year flooding where the contributing drainage area is less than 1 square mile, and areas protected from the 100- year flood by levees. No base flood elevationsor depths are shown within this zone. I- 100.YEAR FLOOD PLAIN -, FlOODWAY FRINGE FLOODWA,Y FLOOOWAY FRINGE STREAM CHANNEl. FLOOD ELEVATION WHEN CONFINED WITHIN FL.OODWAY AREA OF FLOOD PLAIN THAT COULD BE USEO FOR DEVELOPMENT BY RAISING GROUND S~~RGE. LINE AB IS THE FLOOO ELEVATION BEFORE ENCROACHMENT. LINE CD IS THE FLOOD ELEVATION AFTER ENCROACHMENT. . .SURCHARGe IS NOT TO EXCEED 1.0 FOOT IFIA REQUIREMENT) OR LESSER AMOUNT IF SPECIFIED BY STATE, Figure 10. Floodway Schematic 17