Geology topics

Seth A. Siefken

Publications and source records attributed to Seth A. Siefken.

4 recordsLinked to original sources

USGS2025

Methods for peak-flow frequency analysis for streamgages in or near Montana, North Dakota, South Dakota, and Wyoming

The U.S. Geological Survey, in cooperation with the Montana Department of Natural Resources and Conservation, North Dakota Department of Water Resources, South Dakota Department of Transportation, and the Wyoming Water Development Office, has developed standard methods of peak-flow frequency analysis for studies in Montana, North Dakota, South Dakota, and Wyoming. These methods describe the implementation of national flood frequency guidelines described in Bulletin 17C ( https://doi.org/10.3133/tm4B5 ) for the four States and deviations from Bulletin 17C standard procedures to accommodate unusual hydrologic conditions. A U.S. Geological Survey data release accompanying this report ( https://doi.org/10.5066/P1WHRK8H ) provides example peak-flow frequency analyses for selected streamgages in the study area. The methods described in this report can be used to publish similar data releases for other streamgages in the study area.

Montana, North Dakota, South Dakota, Wyoming↗

USGS2024

June 2022 floods in the Upper Yellowstone River Basin

Extraordinary floods surged down the Yellowstone River and its tributaries in northwestern Wyoming and south-central Montana on June 13–15, 2022. During the flood, U.S. Geological Survey staff worked to maintain real-time data from streamgages by making field measurements of streamflow and repairing damaged equipment while communicating the latest streamflow information with the public and with local, State, and Federal agencies. After the flood, staff surveyed high-water marks, computed peak streamflow at streamgages unreachable during the flood, and updated flood-frequency estimates for streamgages in the Upper Yellowstone River Basin. Streamflows were the highest on record at 17 streamgages in the Upper Yellowstone River Basin. River stages were highest on record at most of those streamgages. The flood-related data and analyses are summarized in this fact sheet.

Idaho, Montana, Wyoming↗

USGS2024

Yellowstone River fish bypass channel physical and hydraulic monitoring, Montana

The U.S. Geological Survey, in cooperation with the Bureau of Reclamation, began monitoring the Yellowstone River fish bypass channel according to the specifications of the Lower Yellowstone Adaptive Management and Monitoring Plan. The fish bypass channel was constructed to provide upstream migrating fish with a route around a diversion dam. The objective of this study is to monitor the physical and hydraulic characteristics of the bypass channel, including flow split, minimum depth for the deepest continuous 30 cross sectional feet, and mean channel velocity. Data are collected through several sets of measurements within the bypass channel at varying times during the field season. Physical and hydraulic data collected during this study can be used to ensure the hydraulic design criteria of the bypass channel are being met. This report presents the methods used to monitor the physical and hydraulic characteristics of the bypass channel. Examples of the types of data collected and summarized as part of this study are provided using three figures and one table. Data collected for this study are summarized and published in an accompanying U.S. Geological Survey data release. The monitoring data can be used by the cooperating agencies to help describe the preferred hydraulic conditions for Scaphirhynchus albus (Forbes and Richardson, 1905; pallid sturgeon) passage.

Montana↗

USGS2022

Controlling skewness in MOVE3 peak-flow record extensions

Streamgage record extension methods such as the maintenance of variance Type 3 (MOVE3) method improve flood frequency estimates at a target streamgage by incorporating information from a nearby, hydrologically similar index streamgage. Bulletin 17C recommends using a variation of the MOVE3 method to estimate values at the target streamgage for only a subset of the available data at the index streamgage to account for uncertainty in values estimated using MOVE3. Bulletin 17C recommends the most recent index streamgage data be used for the subset unless these data misrepresent the skewness of the extended record. However, no method is provided to select the subset if the most recent data are inappropriate. The objective of this study is to develop such a method to select the subset of peaks by extending Bulletin 17C’s MOVE3 methodology to control the skewness of the extended streamgage record. The new method allows the extended record skewness to be informed by all available peak-flow data at the index streamgage while accurately computing the variance and resulting confidence intervals for flood frequency estimates. An example is presented comparing three different variations of MOVE3 record extension, which produce extended streamgage records with the same mean and variance, but different values of skewness. In the example, the difference in skewness between the three methods causes the results of flood frequency analysis for the 1% annual exceedance probability flood to differ by about 15%, illustrating the importance of considering skewness when using MOVE3 record extension.

Journal of Hydrologic Engineering↗