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<br />did not adequately account for the variance in sediment discharge and water <br />discharge data. Since sediment transport equations based on measured sediment <br />discharges have been derived for 1I)0re types of sediment discharge than have <br />equations based on estimates from the Modified Einstein procedure, subsequent <br />analysis of sediment transport in the Deerlodge Park reach will utilize the <br />measured sediment discharge versus water discharge relations and their corre- <br />sponding annual sediment loads. <br /> <br />The annual total sediment load of 2.04 million ton/yr based on 1982 and <br />1983 measurements agrees with Andrews' (1978, p. 11) estimate of annual total <br />sediment load for Deerlodge Park of 2.0 million ton/yr. His estimate was <br />based on suspended-sediment loads measured at station 09251000 Yampa River <br />near Maybell and station 09260000 Little Snake River near Lily, bedload <br />estimates computed with the Meyer-Peter and Mueller (1948) formula, and an <br />adjustment for the intervening ungaged drainage area. <br /> <br />The flow-duration, sediment-transport-equation method of computing annual <br />sediment loads (Miller, 1951) estimates the amount of annual sediment load <br />transported by successive increments of water discharge, of a given duration. <br />These incremental sediment loads are summed to give the long-term annual <br />sediment load. Cumulative increments of total sediment load are plotted <br />against discharge in figure 7, and the relative portion of total annual <br />sediment load transported by streamflow greater than a specified level is thus <br />illustrated. Approximately one-quarter of theaJ1!1.Ual total sediment load <br />transported by the Yampa River through Deerlodge Park is~carried by-'discharges. <br />greater than" 12,000 ft3/s. On average, such flows are equaled or exceeded <br />about 2.5 percent of the time (fig. 6), or about 9 days per year. <br /> <br />ESTIMATED IMPACTS OF WATER RESOURCE DEVELOPMENT. <br /> <br />Sediment loads computed for the Yampa River at Deerlodge Park are esti- <br />mates of long-term, average sediment transport through this reach and into the <br />Vampa Canyon. The annual sediment load and streamflow are influenced by <br />geomorphic, hydrologic, and climatologic conditions prevailing today and in,! <br />the recent past. The Vampa Ri ver appears to be in equi 1 i bri um through the / <br />Deerlodge Park reach. Transport of materi a 1 through th i s -reach_is e'qua 1 ..to <br />the amount of material supplied to it, on an average basis. No physical <br />evidence exists to suggest long-term aggradation or degradation in Deerlodge <br />Park. The flood plain is broad and has no strath terraces to suggest recent <br />progressive downcutting by the river. The river is not bordered by berms or <br />other overbank deposi ts that woul d i ndi cate progress i ve aggradati on. Large <br />cottonwood trees growing on the flood plain indicate that the level of the <br />flood plain has been relatively constant for several decades. Also on the <br />flood plain, near the U.S. Geological Survey gaging station, are adobe and sod <br />buildings that date from about 1903 (Glade Ross, National Park Service, oral <br />ccmmun., 1983). Comoarison of the pattern and position of the Yamoa Ri'!er <br />rr():r! Lily ParK to th~ canyon entrance I documented by survey i r. 1922 3.na by <br />:,~~':2j :::'~I~:ograph/ in 1970, :'~l,leais :-:0 cf,anges except those typicai or .{'~ve:s <br />t~'3nsQorting large sand loads, such 'as bend ;nigration and bar formation. <br /> <br />21 <br />