Powder River: Data for Cross-Channel Profiles at 22 Sites in Southeastern Montana, 1975 through 2019

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Powder River rises in the Bighorn Mountains of Wyoming and flows northward through a semi-arid landscape in Wyoming and Montana to the Yellowstone River. The river drains an area of 34,700 square kilometers and has an average discharge of about 500 million cubic meters per year. Cross-channel profile data were collected at 22 sites on the river and its tributaries from 1975 through 2014.

 

Introduction

Photo of the Powder River in southeastern Montana, with mountains in the background.

This view of the river looking northward, and hence downstream, was taken in October 2012, about 20 kilometers (km) north of the Wyoming-Montana state line, about 4 km downstream from an operating gaging station at Moorhead, Montana (USGS station number 06324500), and about 80 river km upstream from a discontinued gaging station at Broadus, Montana (USGS station number 06324710). The river is emerging from a narrowly-confined reach, and the valley widens northward, bordered by hills of the coal-bearing Fort Union Formation.

Powder River rises in the Bighorn Mountains of Wyoming and flows northward through a semi-arid landscape in Wyoming and Montana to the Yellowstone River. The river drains an area of 34,700 square kilometers and has an average discharge of about 500 million cubic meters per year (or 16 cubic meters per second).

The river in the adjacent photo is at about bed-full flow (12 m3 s-1, Moody and others, 1999), and several riffles with disturbed water can be seen downstream between smooth glassy reaches of the river. A narrow band (~2-4 m wide) of reddish sedge (Scirpus spp.) grows just above the bed-full level along the edge of water with a wider band of mixed grasses (Agropyron repens, A. pauciflorum, Bromus inermis, Elymus canadenis, Spartina pectinata, and S. cynosoroids), willow (Salix exigua), tamarisk (Tamirix ramosissima) and small cottonwood seedlings and trees (Populus sargentii) on the flood plain. Three terrace levels have been identified along the river (Leopold and Miller, 1954; Moody and Meade, 2008). The first is the Lightning Terrace with small cottonwood trees (seen here without leaves) adjacent to the floodplain in the right-center of the photo. The second is the Moorcroft Terrace seen best forming the left bank and extending as a flat surface to the left (west) with a few large cottonwood trees still retaining their green leaves. The third is the colluvial Kaycee Terrace that grades slowly upwards and meets the hills of the Fort Union Formation. It can be seen on the right side at the base of the hills and in the far distance on the left side, west of the white ranch buildings.

Powder River has no dams or other large-scale human modifications, which, combined with its substantial suspended-sediment load (2-3 million metric tons per year), makes it an optimal outdoor laboratory for studying natural fluvial processes (Moody and Meade, 1990; Hubert, 1993; Moody and others 2002). A research program was started in 1975 and, by 1977, 20 channel cross sections had been established in the 93-km reach, with the uppermost (PR113) just upstream from the Moorhead gage and the lowermost (PR206, see map) just downstream from the Broadus gage. Cross section PR120 crosses the river in the above photo at a point near where the shadows from the large cottonwood trees on the left bank meet the river downstream from the apex of the nearer bend (Moody and others 1999; Pizzuto and others, 2008). An extreme flood in 1978 (779 m3 s-1) (Moody and Meade, 2008; Meade and Moody, 2013) was a major disturbance that widened the channel, caused two meander cutoffs (not visible in this photo), and deposited fresh sediment on the Lightning and Moorcroft terraces. Two additional cross sections (PR 122A and PR141A) were established on the cutoffs in 1979, and the post-flood response has been monitored at most channel cross sections through 2012. Elevation datum is NGVD29, and all cross-sectional data (1975-1998) also are available in the Results tab of this page.

Map showing channel cross section locations for Powder River study area.

Map showing locations of 20 channel cross sections and the tributaries of Powder River in the study reach. The dashed line indicates the approximate boundary of the visually-obvious valley. Longitude and latitude tick marks are on the outside of the border, and tick marks for the universal transverse mercator (UTM) gride are on the inside of the border. DA and DV are the identification letters for the 100,000-meter-square grid. "Forty-fifth parallel" (45o 00' N) is the Montana-Wyoming state line. "PR113" is the cross section identification.

Current Discharge Data 

 

Citation For This Dataset

Moody, J.A., and Meade, R.H., 2014, Powder River: Data for cross-channel profiles at 22 sites in southeastern Montana from 1975 through 2014, Washington: U.S. Geological Survey Data Set, doi:10.5066/F70Z719C.

General Data

 

Cross Section PR113

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Cross Section PR116

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Cross Section PR120

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Cross Section PR122

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Cross Section PR122A

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Cross Section PR125

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Cross Section PR130

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Cross Section PR136

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Cross Section PR141

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Cross Section PR141A

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Cross Section PR141P7

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Cross Section PR147

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Cross Section PR151

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Cross Section PR156

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Cross Section PR156A

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Cross Section PR163

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Cross Section PR167

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Cross Section PR180

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Cross Section PR183

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Cross Section PR191 

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Cross Section PR194

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Cross Section PR206

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