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<br />STUDY AREA DESCRIPTION <br /> <br />bdsin, F~r~hcr. ~uch a division is to facili,at~ tha, each ~ub-ba~in <br />~ould behave in a rea~onably uniform manner durln~ a storm, and to <br />enable the routing and lagging computation~ to be perfonned ~ithin a <br />more credible accuracy level. <br /> <br />The draina~e area above the study reach was divided into a <br />total of 15 sub-baa ins. The~e sub-basins shown on Plate 1, are desig- <br />nated G-l through G-IO for the Gunnison River proper and T-l through T-5 <br />for the Tomichi Creek proper. The size. length. slope, aspect, eleva- <br />tion (lo~er/upper). hydrologic soil group and vepetative cover type for <br />each sub-basin are presented in Table 1. Also, a partial list of the <br />same parameters were derived for the entire area above outlet points to <br />individual sub-basins. These parameters are presented in Table 2,und <br />an explanation of how they were developed is inel~ded in the Technical <br />Addendum. <br /> <br />Location <br /> <br />The at"dy a:rca IS loeated in th"vicinityof the City of <br />Gunnison, west of the Continental Dlvide in Colorudo. The r.unnison <br />River Basin is bordered on the north by r.rand ~e3n nnd the West Elk <br />Mountains group, on the east by the Sawatch Ran~e, on the south by the <br />Cochetopa Hills and the San Juan Mountain ~roup, and on the west by the <br />Upcompahgre Plateau. The Gunnison River :represents the principal tribu- <br />tary of the upper Colorado River and drains areas embracln~ some of the <br />most rugged country in the entire Colorado River BaSin. <br /> <br />DrainaRe Basin Characteristics <br /> <br />Basin parameters were estimated using existing land use con_ <br />ditions. These values were based on infotmation obtained from aerial <br />photographs, contour maps, field inspections and other basic data re- <br />ports obtained frorothe local governments. Due to the larg"s:l.c of the <br />drsinageareaaffectIngthestudyreach,coupledwithboehthehis- <br />torieal and projected future low level of land development in the basin. <br />it 16 anticipated that the future development withi" the basin will not <br />ar?r~eiably sffect the peak fl~s. <br /> <br />The average 8Ititu~.. of the Gunn160n Rlver Basin above the <br />study area is relatively high, ranging in elevation fram approximately <br />7,600 feet above mean sea 1"vel at Tomlchi Cr"ek confluence with the <br />Gunnison RiveT to ovct 14,000 fcet at the high pe~k~ of the Continental <br />Divide. <br /> <br />TheGunnisonRtver,fOt"l'n<'dbytheconfluenceofth",Taylorand <br />East Rivers at Al~ont ha$ a well-developed strea~ pattern with lntlu~in~ <br />tributaries from different dIrections. Th" h.rger of these tributaries <br />contributing to the flooding problems in the study area include Ohio and <br />TOlllichiCr..eks. <br /> <br />The drainage basin characteristics are described in terms of <br />smaller sub-basins comprisin~ the totul drainage basin lnfluenein~ the <br />study reach. The basin above the study area is divided Into r.unnison <br />River proper design"ted "G" and Tomtchi (;H'ck proper desigaated "T.'. <br />Each of these two mujor basin". forming a portion of the total r.unnisoo <br />River basin, WaS divided Into smaller sub-basin~. Where applicable. <br />these sub-basins were selected to have theiT o\lth,r polnts coincide with <br />~he locatio" of suea,.flo", gai(ing slat ions locHeu in ~h.. nunnhon River <br /> <br />8 <br /> <br />, <br />