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<br />plus any adjacent flood plain areas, that must be kept free of <br />encroachment so that the lOa-year flood can be carried without <br />substantial increases in flood heights. Minimum standards of <br />the FEMA limit such increases to 1.0 foot, provided that <br />hazardous velocities are not produced. The floodways in this <br />study are presented to local agencies as minimum standards <br />that can be adopted directly or that can be used as a basis <br />for additional floodway studies. The floodways presented in <br />this study are computed on the basis of equal conveyance <br />reduction from each side of the flood plain. The results of <br />these computations are tabulated at selected cross sections <br />for each stream segment for which a floodway was computed. <br />(Table 2) <br /> <br />As shown <br />boundaries <br />sections, <br />where the <br />together <br />shown. <br /> <br />on the Flood Insurance Rate Map, the floodway <br />were determined at cross sections; between cross <br />and the boundaries were interpolated. In cases <br />floodway and lOa-year flood boundaries are close <br />or collinear, only the floodway boundary has been <br /> <br />The area between the floodway and boundary of lOa-year flood <br />is termed the floodway fringe. The floodway fringe thus <br />encompasses the portion of the flood plain that could be <br />completely obstructed without increasing the water-surface <br />elevation of the laO-year flood more than 1.0 foot at any <br />point. Typical relationships between the floodway and <br />floodway fringe and their significance to flood plain <br />development are shown in Figure I. <br /> <br />No floodway was computed for the Arkansas River since the <br />floodway, if presented, would lie totally outside the <br />corporate limits of Florence. <br /> <br />,oo.YE_I"t.OOOl"l.AJN <br /> <br />--- <br /> <br />MODW.' 1 <br />FRINGE <br /> <br />FI.OODWAY <br /> <br />I.OOOWA't <br />F~NGE <br /> <br /> <br />,,~ <br />CHANNEl. <br /> <br /> <br />AREA Of' FLOOOPl.AlN THAT COULO BE USEO FOR <br />[)E:YELOPMENT BY RAISING GROUND <br /> <br />FLOOD ELEVATION SEmllE <br />ENCROACHMENT ON FLOODPlAIN <br /> <br />LINE All 1$ THE FI.OOO EI.EYATION IlEFORE ENCROACHMENT. <br />LINE CO 1$ THE FI.OOO EI.EVATIOIIl AFTER ENCROACHMENT. <br />"'SURCHARGE IS NOTTO EXCEED 1.0 FOOT (FlA REQUIREMENn OR LESSER AMOUNT IF SPECIFIED BY STATE_ <br /> <br />Floodway Schematic <br /> <br />Figure 1 <br /> <br />-10- <br />