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<br />The general rainstorm floods result from rainfall over areas of large areal extent. Rainfall <br />from this type of storm may occur over several days, Because of this time duration, the <br />affected streams rise relatively slow; sometimes over a period of several days, The <br />duration of the flood period also is sometimes of considerable length, Because of the large <br />areal extent of rainfall, more tributaries contribute to the peak discharge on the South <br />Platte River, This results in increasin~, discharge progressively downstream over a <br />considerable length of the South Platte River. However, downstream from the contributing <br />tributaries, the effects of valley storage cause flood discharge attenuation, <br /> <br />Erosive effects can be considerable in the event of any flood regardless of ~s origin, <br />Floods resulting from intense rainstorms typically create severe erosion damages in a short <br />period of time due to the relatively large peak discharge and high velocity of the <br />floodwater, Erosion damages from snowmett or general rainstorm floods usually resutt <br />from prOlonged exposure of the floodwatElr because of the long duration typical of these <br />floods, <br /> <br />Intense rainstorm floods as well as general rainstorm floods have occurred 011 the South <br />Platte River, Examples of the intense storms are the 1965 events on Plum Creek and <br />Bijou Creek and the 1976 event on the Big Thompson River. Examples of the larger more <br />generalized storms are the 1969 and 197:3 events producing flooding on the South Platte <br />River. <br /> <br />3.3,2 Arkansas River <br /> <br />Basin Descriotion- The Arkansas River is formed by the East Fork and Tennessee Fork, <br />which un~ near Matta, From the junction to Parkdale, the Arkansas River flows through <br />a succession of narrow valleys divided by short canyons. At Parkdale, the river plunges <br />into the Royal Gorge, emerging from ~ just above Canon C~y, and below that, flows <br />through a valley increasing in wiclth as far as Pueblo, Beyond Pueblo, the river flows <br />across the plains to the State Line and then into Kansas, <br /> <br />Floodina Characteristics- Above the Royal Gorge, the Arkansas River is not subject to <br />heavy floods. A few of its upper tributaries are subject to cloudburst floods, but the volume <br />of these floods are too small to seriously affect the Arkansas ~sell. <br /> <br />Colorado Flood <br />Hydrology Manual <br /> <br />3,3 <br /> <br />fRI'FT <br />