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Magnitude and Frequency of Peak and Low Flows in the Elkhorn River Basin, Nebraska, 1881–2022

Scientific Investigations Report 2026-5004
Prepared in cooperation with Nebraska Department of Transportation
By:  and 
https://doi.org/10.3133/sir20265004

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Abstract

Flood-frequency analysis is based on records of annual maximum instantaneous flows observed at long-term streamgages with 10 years or more of operation. Since the last flood-frequency analysis in Nebraska, an additional 30 years of annual peak-flow data have become available, and new flood-frequency analysis techniques have been developed. Moreover, the Elkhorn River Basin in north-central and eastern Nebraska has experienced two of the three highest magnitude floods on record in 2010 and 2019. The U.S. Geological Survey, in cooperation with the Nebraska Department of Transportation, analyzed flow frequency at streamgages in the Elkhorn River Basin in Nebraska.

Flow data from the U.S. Geological Survey and the Nebraska Department of Water, Energy, and Environment annual hydrographic reports were utilized to analyze peak flows. The Peak flow FreQuency (PeakFQ) software was used to perform a flood-frequency and nonstationarity analysis on the selected streamgages in the Elkhorn River Basin in Nebraska. Results of the peak-flow nonstationarity analysis indicate that, of the 23 streamgages analyzed for peak-flow frequency, 4 showed trends that were likely increasing for annual peak flows, whereas 3 indicated trends that were somewhat likely to be increasing. For 11 streamgages, the trend was categorized as about as likely as not, meaning there is less than a 70-percent chance of the trend being either upward or downward. Additionally, 2 streamgages exhibited trends that were somewhat likely to be decreasing, and 3 streamgages showed trends that were likely decreasing.

Low-flow streamflows and nonstationarity in the Elkhorn River Basin were analyzed for low flow periods representing the 1-day, 7-day, and 30-day flows at 21 streamgages using the Hydrologic Toolbox software. Spatially, the nonstationarity analysis results indicated likely increasing or somewhat increasing trend likelihoods for the 1-day, 7-day, and 30-day low flows for many of the Elkhorn streamgages downstream from the Elkhorn River at Ewing, Nebr., streamgage (U.S. Geological Survey station 06797500) and on eastern tributaries during the period of record.

Suggested Citation

Strauch, K.R., and Dietsch, B.J., 2026, Magnitude and frequency of peak and low flows in the Elkhorn River Basin, Nebraska, 1881–2022: U.S. Geological Survey Scientific Investigations Report 2026–5004, 17 p., https://doi.org/10.3133/sir20265004.

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Purpose and Scope
  • Previous Studies
  • Site Selection
  • Statistical Methods
  • At-Station Flow Statistics in the Elkhorn River Basin
  • Summary
  • References Cited
  • Appendix 1. Recurrence Interval and Corresponding Exceedance Floods, and Non-Exceedance Flow for the 1-Day, 7-Day, and 30-Day Low Flows for Streamgages in the Elkhorn River Basin
Publication type Report
Publication Subtype USGS Numbered Series
Title Magnitude and frequency of peak and low flows in the Elkhorn River Basin, Nebraska, 1881–2022
Series title Scientific Investigations Report
Series number 2026-5004
DOI 10.3133/sir20265004
Publication Date June 08, 2026
Year Published 2026
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Central Plains Water Science Center
Description Report: iv, 17 p.; 2 Appendix Tables; Data Release
Country United States
State Nebraska
Other Geospatial Elkhorn River basin
Online Only (Y/N) Y
Additional Online Files (Y/N) Y
Additional publication details