Laserfiche WebLink
<br />. <br /> <br />e) Floodways <br /> <br />. <br /> <br />. <br /> <br />Within Colorado, two basic concepts for dividing the <br />100-year floodplain into an the floodway (high- <br />hazard area) (see Glossary) and the flood fringe <br />(low-hazard area) (see Glossary) are suggested as <br />options to local units of government (see Fig- <br />ure ). These options are: <br /> <br /> <br />. <br /> <br />The Floodway Concept, which specifies an allow- <br />able rise (.5' or 1.0') in water surface eleva- <br />tions due to encroachment into the floodplain <br />while still allowing passage of the 100-year <br />flood, provided hazardous velocities are not <br />produced. (A hazardous velocity condition exists <br />when the velocity rate exceeds 3 fps.) <br />The Hazard Area Concept, where the area with a <br />water depth of 18 inches or greater and a water <br />velocity of 3 feet per second or greater is con- <br />sidered the high hazard area, which must be kept <br />free of development. <br /> <br />. <br /> <br />The Floodway Concept is based on a rise criterion. <br />the rise criterion assumes that encroachment occurs <br />on the edges of the floodplain on both sides until <br />the 100-year water surface is increased by .5 foot <br />or 1.0 foot. It is suited to wide, flat-sloped, and <br /> <br />-31- <br />