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Related Flood Studies In 1978 the Corps of En9ineers prepared a Floodplain Information Report for the Ar~ansas River Basin at Florence, Colorado (Reference 1). The Ar~ansas River hydrologic and hydraulic analyses contained therein ....ere used for this study. GreatOivideEngineering has comp1eted a Floodplain Information Report on Northeast Canon Orainage for Canon City, Fremont County and the Colorado OIater Conservation Board (COICB). The Great Divide Engineering study revises and supercedesa Soil Conservation Service study entitled, "Flood Hazard Analysis Portions of Red Canyon Ora.... and Tributaries, Fremont County, Colorado, January, 1976," (Referenceg). ThelOO-year floodplain produced from Northeast Canon drainage is joined into the Ar~ansas River 100~year floodplain and is delineated on Plate 9. Appendix ll, of this report. STUDY AREA OESCRIPTION Drainage Basin Characteristics The Ar~ansas River basin above Canon City is characterized by high mountain valleys surrounded on three sides by mountains reaching altitudes of more than 14,000 feet. The basin is ccrnpletely surrounded on three sides and part of the fourth by mountain ranges that act as orographic barriers to major storm systems, Belo.... Canon City the valley opens up into a ....ide river valley and....ith less orographic barriers, The frequency and volume of past floods also silo.... dramatic increases belo.... Canon City. The portion of the Ar~ansas River under consideration in this study has its lower limits at 0.2 mile below the ColoradO US Higllway bridge (see Basin MapPlatell. Orainageareasforselectedpointsalongthestudyreachare given in Table 1. Camp Dresser & McKee is currently preparing a Flood Insurance Study in Canon City for the Federal Emergency Management Agency. In the Flood Insurance Report, five tributaries of the Ar~ansas River are being studied along ....ith the Ar~ansas River. Th€-se tributaries are Northeast Canon drainage. Southeast Canon drainage, Sand Creek, Forked GulCh and West Forked Gulch. The 100- and SOO-year floodplains will be delineated for each flooding source studied. Flooding infonnation for Northeast Canon drainage will coincide ....ith the CWCB study. For the Arkansas River al1 infonnation will coincide ....ith this study and all tributaries will use the Arkansas River as the regulatory flooding source. Table I location Drainage Areas Area (squaremlles) Arkansas River at Canon City Arkansas River at Florence (just upstream of Florencel 3,117 3,S46 The nonnal annual precipitation forCanonClty/Florence, Colorado area is 14 inches of....hich 60 percent falls from May to September. In the Arkansas River basin pre<:ipitdtion varies from 11.8 inches per year at Pueblo to more than 40 inChes on the pea~s ....est of leadville. most of it In the fonn of sno..... The temperature varies along the basin from a mean minimum and muimum of 22.0~ F and 49.S" F at leadville to a mean minimllll and ma~imum temperature of 37.j" F <Ind 6a.0~ F at Pueblo. Above Canon City the basin topography is typical mountain terrain with characteristic alpine vegetation. Below Canon City the basin topography is much like that of the lower foothills and plains area. Study Ruch Description The study reach is located along the Arkansas River in Fremont County, Colorado. The lo....er 1 imit e~tI!nds to 0.2 miles belOW the Colorado 115 bridge near Florence, and the upper limit is located at the ufstream corporate 1 imits of Canon City (see jnde~ !l\aps, ~lates 2.j <lnd 2-Il,. Th.. river in this area is well defined nowing through allUVial material with an average slope of 48 feet per mile. Within the study reaCh the stream channel is generally flatand....ide. The types of land use permitted along the river will substantially affect the e~tent of loss and damage brought about by flooding. With sound planning practices. losses due to flooding can be greatly r",dl.lcedby limiting the high risk development in the flood hilzardarea. 4 5