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2.0 AREA STUDIED 2.1 Scope of Study This ['lood Insurance Study covers the incorporated area of tre Town of De Beque, Mesa County, Colorado. The area of study is shown on the Vicinity Map (Figure 1), ' The flooding from Roan Creek was studied by detailed methods for its entire reach within the Town of De Beque. The area studied by detailed methods extent and validity of availabl~ hydraulic data, was selected based on existing hydrologic the and 2.2 Community Description The Town of De Beque, Mesa County, Colorado, is located approximately 2 miles south of the Garfield county boundary and approximately 2S miles northeast of the City of Grand Junction, Colorado. According to 1980 census data, De Beque has a population of 279, an increase of approximately 44 percent from the 1970 census (Reference 1). The topography is primarily plateau-like tablelands deeply cut by watercourses that form steep canyons. The region is rich in coal and oil shale deposits. The climate of the area 1S influenced by Pacific storm systems that move easterly. The nearest National Weather Service station, representative of the lower part of the basin, is at Rifle. The mean annual temperature at Rifle is 470F, with approximately 109 days of growing seaso~ between spring and fall frost (reaching temperatures of 32DF). The mean a~nu.l precipitation at Rifle is just over 11 inches (Reference 2). This increases to approximately 20 to 2S inches at the higher elevations. Winter precipitation is usually in the form of snow, and occurs from late October to early April. The soils include Mollisols at the higher elevations in the upper basin and Aridisols and Entisols in the lower part of the basin. Fluvents are dominant in areas adjacent to stream channels. The geologic formations include the Tertiary Green River, which contains oil shale deposits, and the Wasatch. The higher ridges have growths of conifer and aspen, while lower areas have juniper and pinyon interspersed with sagebrush. Wi llows and cottonwoods grow along the st reams. There is al so some irrigated cropland at lower elevations along the streams. The floodplain along Roan Creek contains areas of irrigated pasture and hayland interspersed with areas of natural vegetation. Along the channel, the vegetation consists of a variety of forbs, grasses, sedges, and rushes, interspersed wi~h 2