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<br />~ <br /> <br />PINE RIVER RANCH <br />FLOOD DISCHARGE ESTIMATE <br />FOREST SERVICE METHOD <br /> <br />LARGE CHANNEL <br />AVERAGE BANK WIDTH <br /> <br />!':i1YfALL CHANNEL <br />flVERAGE BANK WIDTH <br /> <br />Stat ioy, <br />(feet) <br /> <br />Bay,kf'JII <br />Width <br />(Feet) <br /> <br />St a.t i CIY'1 <br />(fE'I"t) <br /> <br />Bankfull <br />Width <br />(Feet) <br /> <br />upper <br />rniddle <br />lower <br /> <br />79 <br />89 <br />157 <br /> <br />UppE'I~ <br />rniddle <br />lOWE'l:" <br /> <br />31 <br />44 <br />66 <br /> <br />Average <br /> <br />108.33 <br /> <br />Ave'l~age <br /> <br />47 <br /> <br />FLOOD DISCHARGE ESTIMATE <br /> <br />-------______________________.___..__n______.__________._ <br /> <br />Flood <br />Discharge <br />Frequency <br />(Years) <br /> <br />..~. . <br /> <br />Flood <br />Dischat"ge <br />(cfs) <br /> <br />Equat ioy, <br /> <br />1.5 <br />10 <br />20 <br /> <br />25 <br /> <br />3960 <br />8700 <br />1070121 <br />11500 <br />13900 <br />17800 <br /> <br />=.96*(ave width**1.65l <br />=1.5YR flood * 2.2 <br />=1.5YR flood * 2.7 <br />=1.5YR flood * 2.9 <br />=1.5YR flood * 3.5 <br />=1.5YR flood * 4.5 <br /> <br />50 <br />100 <br /> <br />Reference: U.S. Forest Service Region 2 Water Resource <br />Analysis Systern "Channel Geornetry and <br />Culvert Sizing", May 1984 <br />