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. . . STUDY AREA DESCRIPTION Community Description Rockvale is located in Fremont County in the foothills of south central Colorado. Rockvale is located to the south of the Arkansas River mainstem and is approximately 100 miles south of Denver, and 6 miles southeast of Canon City. Rockvale is at an elevation of about 5,600 feet. Economic activities in the general vicinity include cattle ranching, small scale coal mining, and tourism. The Colorado State Penitentiary and the Royal Gorge of the Arkansas River are located in nearby Canon City. The area studied for the FIRM is the incorporated area of the Town of Rockvale as of October 15, 1985. Watershed Description The two streams with approximate floodplain information, as shown on Rockvale's FIRM, are Oak Creek and South Oak Creek. South Oak Creek flows into Oak Creek within the corporate limits of Rockvale. Oak Creek flows northerly into the Arkansas River several miles north of Rockvale near Florence, Colorado. The headwaters of Oak Creek originate in the Wet Mountains to the southwest of Rockvale at elevations in excess of 9,000 feet. The climate of the Rockvale area is semi-arid to arid, and precipitation in the area varies from a mean annual of 12 inches in Florence to a mean annual of 20 inches in the mountains to the south. The temperature varies from a mean minimum of about 20 degrees F in January to a mean maximum of about 90 degrees F in July. Floodinl! Problems and Floodinl! Historv A majority of the flooding problems in the Rockvale vicinity are caused by cloudburst-type storms over the foothills which usually occur during the summer months of June, July, and August. Characteristics of that type of flooding include high intensity, short duration rainstorms of limited areal extent. Those storms result in flash floods causing high peak flows with a relatively small volume of water over a short duration. Even though slopes are much steeper in the upper part of the Oak Creek watershed, dense vegetation in those areas serves to reduce rainfall runoff. A greater percentage of the runoff is permitted by the sparse vegetation of the foothills and pasture lands at the lower elevations, Flooding from general rainstorms may also occur during the months of July through October. General rainfall flooding is characterized by higher peak flows with a moderate volume and a moderate duration. Flooding is more severe when antecedent rainfall has resulted in saturated ground conditions or the ground is frozen and infiltration is minimal. Less frequently, flooding in Rockvale may occur in the spring and early summer as a result of rapid melting of snowpack located on the mountains to the south and west. Snowmelt flooding is