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<br />hazard. For purposes of the National Flood Insurance Program, the <br />concept of a floodway is used as a tool to assist local communites in <br />thi s aspect of fl ood pl ain management. Under this concept, the area <br />of the 100-year flood is divided into a fl oOdway and a floodway <br />fringe. The fl oodway is the channel of a stream, pl us any adj acent <br />flood plain areas, that must be kept free of encroachment in order <br />that the 100-year fl ood may be carried wi thout substantial increase <br />in fl ood heights. Minimum standards of the FEMA 1 imit such increases <br />in flood heights to 1.0 foot, provided that hazardous velocities are <br />not produced. The floodways in thi s report are presented to local <br />agencies as minimum standards that can be adopted or that can be used <br />as a basis for additional studies. <br /> <br />The fl oodways presented in thi s study were computed on the basi s of <br />equal conveyance reduction from each side of the flood plain. The <br />results of these computations were tabulated at selected cross sec- <br />tions for each stream segment for which a fl oOdway was computed <br />(Table 3). A floodway was only computed for the Arkansas River. <br /> <br />As shown on the Flood Boundary and Floodway Map, the fl oodway wi dths <br />were determined at cross sections; between cross sections, the <br />boundaries were interpolated. In cases where the floodway and 100- <br />year fl ood boundaries are close together or col inear, only the fl ood- <br />way boundary has been shown. <br /> <br />The area between the fl oodway and the boundary of the 100-year fl ood <br />is termed the floodway fringe. The floodway fringe thus encompasses <br />the portion of the flood plain that could be completely obstructed <br />without increasing the water-surface el evation of the 100-year fl ood <br />more than 1.0 foot at any point. Typical rel ationshi ps between the <br />floodway and the floodway fringe and their significance to flood <br />plain development are shown in Figure 2. <br /> <br />I- <br /> <br />, OO-VEAR FLOOD PLAIN <br /> <br />"I <br /> <br />FLOODWAY <br />FRINGE <br /> <br /> <br />FLOODWAY <br /> <br />FLOODWAY <br />FRINGE <br /> <br />STREAM <br />CHANNEL <br /> <br />FLOOD ELEVATION WHEN <br />CONFINED WITHIN FLOODWAY <br /> <br /> <br />AREA OF FLOOD PLAIN THAT COULD <br />BE USED FOR oeVELOPMENT BV <br />RAISING GROUND <br /> <br />LINE A8 1$ THE FLOOD ELEVATION BEFORE ENCROACHMENT. <br />LINE CD 1$ THE FLOOD ELEVATION AFTER ENCROACHMENT. <br />. 9UACHAAOE 18 NOT TO EXCEED I, D FOOT I FEMA REQUIREMENTI OR LESSER AMOUNT IF &PECIFlm II'f STATE, <br /> <br />Floodway Schematic <br /> <br />Figure 2 <br /> <br />10 <br />