Channel changes of Powder River between Moorhead and Broadus, Montana, 1939-1978
Water-Resources Investigations Report
83-4128
By: H. A. Martinson
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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)
Suggested Citation
Martinson, H.A., 1984, Channel changes of Powder River between Moorhead and Broadus, Montana, 1939-1978: U.S. Geological Survey Water-Resources Investigations Report 83-4128, vi, 62 p. :ill., maps ;28 cm., https://doi.org/10.3133/wri834128.
| 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 |
| DOI | 10.3133/wri834128 |
| Year Published | 1984 |
| Language | ENGLISH |
| Publisher | U.S. Geological Survey, |
| Description | vi, 62 p. :ill., maps ;28 cm. |