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<br />second. Overbankvelocltieswouldbeaboutland4feetpersecond, <br />respectIvely, upstream and downstream from the dam. Channel velocItIes <br />onCastleandHunterCreekswouldbellboutl5feetpersecond. Overbank <br />velocitIes would be about 5 feet per second. <br /> <br />TABLE 5 <br /> <br />RATES OF RISE AND DURATION OF FLOODING <br /> <br />WlIter flowIng at a velocity of 8 feet por second or greater can <br />cause severe erosion of streambanks and Is capable of transporting <br />large rocks. VelocIties In the range of 6 to e feet per second could <br />anode fll I around bridge abutments. Water flowIng at about 2 feet per <br />sacondorlesswlll deposit debris and silt. Itlsexpectadthat <br />velocIty of flow during a Standard Project Flood would be slightly <br />hIgher than durIng an IntermedIate Regional Flood. <br /> <br />Flood <br /> <br />Maxl"1Um HeIght TIme <br />Rate of of of <br />Rise Rlse(a) Rlse(b) <br />It/hr It days <br />ROARING FORK RIVER AT MILE 44.73 <br /> <br />Duration <br />of <br />FloodStaqe <br />days <br /> <br />Intermediate Regional <br />Standard Project <br /> <br />Intermediate Roglonal 0.1 3.7 6.5 <br />Standard ProJect 0.2 6.2 11.0 <br />CASTLE CREEK AT MILE 0.52 <br />0.03 0.8 1.0 <br />0.03 1.3 4.5 <br />HUNTER CREEK AT MILE 0.26 <br />0.03 0.9 1.5 <br />0.04 1.6 4.0 <br /> <br />11.0 <br />18.0 <br /> <br />Intermediate Regional <br />Standllrd Project <br /> <br />2.0 <br />'.0 <br /> <br />RATES OF RISE AND DURATION OF FLOODING <br /> <br />The RoarIng Fork RIver and CIlstle lInd Hunter Creeks hllve moderate <br />to large drainage basIns. As prevIously noted, floodllows lire produeed <br />by snowmelt, occasionally augmented by rllln. High temperatures over <br />anextendedperlod,usuallyoccurrlngln lateMayandJune,produee <br />maximum flows of lllrge volume. Rates of rise are slow, but duration <br />of flooding Is prolonged. Table 5,whlch ...as developed from toe synthesized <br />stllge hydrographs shown on Plate 3, gives the typical rate of rIse, <br />height of rise, time of rIse, and duration of flood stllge for the <br />Intermediate Roglonal and Standllrd Project FloodS on the streams under <br />study. On the average, the water surfllce of the Standard Project Flood <br />would be 6bout I foot higher than the Intermediate Regional Flood. <br /> <br />3.0 <br />10.0 <br /> <br />(a) nood sta'iJs tevs~ (be'iJinni11{J of owrbank ft,0I>J) to marimwn floodf'LOI>J <br />~eve~. <br />(b) Tims period c01'7'el1ponding to height of :rise. <br /> <br />PHOTOGRAPHS, FUTURE FLOOO HEIGHTS <br /> <br />The levels that the Intermedlllte RegIonal lInd Standard Project Floods <br />are expected to reach at varIous locations in the study area are Indicated <br />on the following photographs. <br /> <br />" <br /> <br />" <br />