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Channel changes of Powder River between Moorhead and Broadus, Montana, 1939-1978

Water-Resources Investigations Report 83-4128

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Abstract

Bank erosion and changes in channel width, length, and pattern were determined for the Powder River between Moorhead and Broadus, Montana using maps of the bankfull channel made from aerial photographs taken during 1939, 1954, 1967, 1973, and 1978. Contemporaneous daily mean and peak discharge records from Moorhead provide the hydrologic data used to interpret the measurements. Magnitudes and frequency of flows were determined for each interval of time delimited by photographs. Bank erosion is related to the number of days that mean discharge was equal to or greater than bankfull (1.5-year flood). Mean channel width ranged between 264 ft (1973) and 415 ft (1967). The channel was wider after periods of higher annual peak flows. The channel lengthened between 1939 and 1978, although at least 12 meanders cut off between Moorhead and Broadus. Variable rates of lengthening in the reach reflect the degree of bedrock control in the valley and local variations in valley slope. Data from the Powder River verify the concept of thresholds of channel pattern stability that were demonstrated experimentally. (USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Channel changes of Powder River between Moorhead and Broadus, Montana, 1939-1978
Series title:
Water-Resources Investigations Report
Series number:
83-4128
Edition:
-
Year Published:
1984
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
vi, 62 p. :ill., maps ;28 cm.