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<br />Bosley Wash Drainage Master Plan Phase I: Watershed Floodplain Delineation
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<br />1.4 Hydraulic Modeling and Floodplain Delineation
<br />
<br />Hydraulic profiles were computed for each of the afore mentioned recurrence intervals using
<br />HEC,RAS (USACOE, 1990), Flood profiles were computed in accordance with CWCB
<br />requirements, The type, size, capacity and location of major conduits, open channels, and storage
<br />facilities were identified and included within the model. HDR developed model geometry using
<br />a combination of aerial mapping supplied by the county, cross-sections surveyed by GJDD, and
<br />USGS quadrangle maps,
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<br />2. BASIN DESCRIPTION
<br />
<br />Bosley Wash is a right-bank tributary of the Colorado River located in Mesa County, Colorado,
<br />The watershed is west of Palisade near unincorporated Clifton, Colorado, The watershed
<br />consists of 3.3 square miles of highly varied terrain including rural, semi-urban, and desert
<br />mountain environments, The Grand Valley, which includes the Bosley Wash Watershed,
<br />displays characteristics typical of an arid, high-desert climate,
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<br />2.1 Basin Development
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<br />The Bosley Wash Basin is divided into two distinct watershed regions, Steep, unimproved
<br />channels originating on the slopes of the Book Cliffs and Mt. Garfield characterize the upper
<br />portion of the basin above 1-70, This portion of the watershed is undeveloped, with most of the
<br />land privately owned, The lower part of this upper watershed is situated on a highly erosive
<br />alluvial fan, capable of generating high runoff rates and large sediment loads during peak events,
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<br />The lower portion of the watershed, south of 1-70, consists of low-density residential and
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<br />agricultural areas, Throughout most of the lower watershed, the Bosley Wash drainage system
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<br />(including its tributary ditches) consists of drainage ditches that have been improved and
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<br />redirected along roads and railroads,
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<br />2,2 Irrigation Ditches
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<br />Four major operating irrigation canals cross the drainage basin below 1-70, These are:
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<br />Page 3
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