Scientific Investigations Report 2013–5035
AbstractPowder River’s second largest flood of record (1919–2012) moved through northeastern Wyoming and southeastern Montana during May 1978. Within a ninety-kilometer reach of the channel in southeastern Montana, the most prominent planform effects of the flood were the growth of meander bends by bank erosion (this was most intense just downriver of bend apexes, causing 1–2 channel widths of lateral displacement) and the erosion of new cutoff channels through the necks of two large and two small meanders. Surveys of cross sections, made before and after the flood, show the responses of the channel to the flood waters, which ranged from minimal (bedrock control) to large (maximum channel curvature in unconsolidated bank and terrace deposits). Geomorphic work done during two weeks of extreme flooding in May 1978, as measured by cross-channel erosion and new sediment deposition, was approximately equal in magnitude to the work done during the two decades (1978–1998) that followed the flood. |
First posted December 16, 2013 For additional information contact: Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge. |
Meade, R.H., and Moody, J.A., 2013, Erosional and depositional changes wrought by the flood of May 1978 in the channels of Powder River, southeastern Montana: U.S. Geological Survey Scientific Investigations Report 2013–5035, 29 p., and 1 map plate, http://dx.doi.org/10.3133/sir20135035.
ISSN 2328-0328 (online)
Abstract
Introduction
Powder River and the Flood of May 1978
Effects of the Flood of 1978 on River Channels
Effects of the Flood of 1978 Compared with the Cumulative Effects of Subsequent
Flows of Less Magnitude
Recollections of the Flood of 1923
Summary
Acknowledgments
References Cited