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<br />4.2 Floodways <br /> <br />Encroachment on floodplains, such as structures and fill, reduces <br />flood-carrying capaci ty, increases :flood heights and velocities, <br />and increases flood hazards in areas beyond the encroachment. One <br />aspect of floodplain management involves balancing the economic <br />gain from floodplain development against the resulting increase in <br />flood hazard. For purposes of the :NFIP, a floodway is used as a <br />tool to assist local communities in this aspect of floodplain <br />management. Under this concept,i the area of the lOa-year <br />floodplain is divided into a floodway and a floodway fringe. The <br />floodway is the channel of a stream~ plus any adjacent floodplain <br />areas that must be kept free of encroachment so that the lOa-year <br />flood can be carried without substantial increases in flood <br />heights. Minimum Federal standards limit such increases to 1.0 <br />foot, provided that hazardous veloci~ies are not produced. <br /> <br />A floodway was not calculated for the flooding source studied. <br /> <br />S.O INSURANCE APPLICATION <br /> <br />For flood insurance rating purposes, flood insurance zone designations <br />are assigned to a community based on the results of the engineering <br />analyses. These zones are as follows: <br /> <br />Zone A <br /> <br />Zone A is the flood insurance rate' zone that corresponds to the <br />lOa-year floodplains that are determined in the Flood Insurance <br />Study by approximate methods. Because detailed hydraulic analyses <br />are not performed for such areas, no base flood elevations (BFEs) <br />or depths are shown within this zone. <br /> <br />Zone AE <br /> <br />Zone AE is the flood insurance rat~ zone that corresponds to the <br />lOa-year floodplains that are dete~mined in the Flood Insurance <br />Study by detailed methods. In most instances, whole-foot BFEs <br />deri ved from the detailed hydraulic janalyses are shown at selected <br />intervals within this zone. <br /> <br />Zone X <br /> <br />Zone X is the flood insurance rate ~one that corresponds to areas <br />outside the SOO-year flooding where ~verage depths are less than 1 <br />foot, areas of lOa-year flooding wi)ere the contributing drainage <br />area is less than 1 square mile, and areas protected from the 100- <br />year flood by levees. No BFEs or; depths are shown wi thin thi s <br />zone. <br /> <br />8 <br /> <br />, <br />ro~ <br />