Skip Links

Skip Links

USGS - science for a changing world

Data Series 372

In cooperation with the Texas Commission on Environmental Quality

Summary of Annual Mean and Annual Harmonic Mean Statistics of Daily Mean Streamflow for 620 U.S. Geological Survey Streamflow-Gaging Stations in Texas Through Water Year 2007

By William H. Asquith and Franklin T. Heitmuller

Abstract

Thumbnail of and link to report PDF (204 MB)

Analysts and managers of surface-water resources have interest in annual mean and annual harmonic mean statistics of daily mean streamflow for U.S. Geological Survey (USGS) streamflow-gaging stations in Texas. The mean streamflow represents streamflow volume, whereas the harmonic mean streamflow represents an appropriate statistic for assessing constituent concentrations that might adversely affect human health. In 2008, the USGS, in cooperation with the Texas Commission on Environmental Quality, conducted a large-scale documentation of mean and harmonic mean streamflow for 620 active and inactive, continuous-record, streamflow-gaging stations using period of record data through water year 2007. About 99 stations within the Texas USGS streamflow-gaging network are part of the larger national Hydroclimatic Data Network and are identified. The graphical depictions of annual mean and annual harmonic mean statistics in this report provide a historical perspective of streamflow at each station. Each figure consists of three time-series plots, two flow-duration curves, and a statistical summary of the mean annual and annual harmonic mean streamflow statistics for available data for each station.The first time-series plot depicts daily mean streamflow for the period 1900–2007. Flow-duration curves follow and are a graphical depiction of streamflow variability. Next, the remaining two time-series plots depict annual mean and annual harmonic mean streamflow and are augmented with horizontal lines that depict mean and harmonic mean for the period of record. Monotonic trends for the annual mean streamflow and annual harmonic mean streamflow also are identified using Kendall’s tau, and the slope of the trend is depicted using the nonparametric (linear) Theil-Sen line, which is only drawn for p-values less than .10 of tau. The history of annual mean and annual harmonic mean streamflow of one or more streamflow-gaging stations could be used in a watershed, river basin, or other regional context by analysts and managers of surface-water resources to guide scientific, regulatory, or other inquiries of streamflow conditions in Texas.

First posted September 11, 2008

  • Report PDF (204 MB)
    Note: To enhance performance or accessibility of the large PDF of the report, it is advised to download the PDF to the user's computer and then open in a PDF viewer, such as Adobe Acrobat Reader. This process is intended to avoid opening the PDF in the user's Web browser and can be accomplished by right-clicking or control-clicking (MacOSX) the link to the PDF and selecting “Save...As...” or “Download...As....” By first downloading to the user's computer, the potential for a requery to the publication server, which might redundantly download the entire PDF, can be avoided.

For additional information contact:

Director, Texas Water Science Center
U.S. Geological Survey
8027 Exchange Drive
Austin, Texas 78754-4733

http://tx.usgs.gov/

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.


Suggested citation:

Asquith, W.H., and Heitmuller, F.T., 2008, Summary of annual mean and annual harmonic mean statistics of daily mean streamflow for 620 U.S. Geological Survey streamflow-gaging stations in Texas through water year 2007: U.S. Geological Survey Data Series 372, 1,259 p.



Contents

Abstract

Introduction

Background and Literature Review

Harmonic Mean Streamflow in Texas

Hydroclimatic Data Network

Definitions of Mean and Harmonic Mean Streamflow

Summary of Mean and Harmonic Mean Statistics of Daily Mean Streamflow in Texas

Time Series of Daily Mean Values

Flow-Duration Curves for Complete Water Years

Annual Mean and Annual Harmonic Mean Streamflow and Interpretive Graphics

Trend Lines by LOWESS

Tests for Monotonic Trends

Statistical Summary

General Discussion

Selected References

Index of Station Numbers (hyperlinked)

Indexed Map of Station Locations (hyperlinked)

Indexed Map of Station Locations to Station Home Pages on Internet (hyperlinked)


Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: http://pubs.usgs.gov/ds/372/index.htm
Page Contact Information: GS Pubs Web Contact
Page Last Modified: Sunday, January 13, 2013, 03:59:11 PM