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Open-File Report 2008–1284

Office of Surface Water

PFReports: A Program for Systematic Checking of Annual Peaks in NWISWeb

By Karen R. Ryberg

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Introduction

The accuracy, characterization, and completeness of the U.S. Geological Survey (USGS) peak-flow data drive the determination of flood-frequency estimates that are used daily to design water and transportation infrastructure, delineate flood-plain boundaries, and regulate development and utilization of lands throughout the Nation and are essential to understanding the implications of climate change on flooding. Indeed, this high-profile database reflects and highlights the quality of USGS water-data collection programs. Its extension and improvement are essential to efforts to strengthen USGS networks and science leadership and is worthy of the attention of Water Science Center (WSC) hydrographers.

This document describes a computer program, PFReports, and its output that facilitates efficient and robust review and correction of data in the USGS Peak Flow File (PFF) hosted as part of NWISWeb (the USGS public Web interface to much of the data stored and managed within the National Water Information System or NWIS). Checks embedded in the program are recommended as part of a more comprehensive assessment of peak flow data that will eventually include examination of possible regional changes, seasonal changes, and decadal variations in magnitude, timing, and frequency. Just as important as the comprehensive assessment, cleaning up the database will increase the likelihood of improved WSC regional flood-frequency equations. As an example of the value of cleaning up the PFF, data for 26,921 sites in the PFF were obtained. Of those sites, 17,542 sites had peak streamflow values and daily values. For the 17,542 sites, 1,097 peaks were identified that were less than the daily value for the day on which the peak occurred. Of the 26,921 sites, 11,643 had peak streamflow values, concurrent daily values, and at least 10 peaks. At the 11,643 sites, 2,205 peaks were identified as potential outliers in a regression of peak streamflows on daily values.

Previous efforts to identify problems with the PFF were time consuming, laborious, and often ineffective. This new suite of checks represents an effort to automate identification of specific problems without plotting or printing large amounts of data that may not have problems. In addition, the results of the checks of the peak flow files are delivered through the World Wide Web with links to individual reports so that WSCs can focus on specific problems in an organized and standardized fashion.

Over the years, technical reviews, regional-flood studies, and user inquiries have identified many minor and some major problems in the PFF. However, the cumbersome nature of the PFF editor and a lack of analytical tools have hampered efforts at quality assurance/quality control (QA/QC) and subsequently to make needed revisions to the database.

This document is organized to provide information regarding PFReports, especially those tests involving regression and to provide an overview of the review procedures for utilizing the output. It also may be used as a reference for the data qualification codes and abbreviations for the tests. Results of the checks for all peak flow files (March 2008) are available at http://nd.water.usgs.gov/internal/pfreports/.

Version 1.0

Posted September 2008

For additional information contact:
Director, USGS North Dakota Water Science Center
821 E. Interstate Ave.
Bismarck, ND 58503
(701) 250–7400

Or visit the North Dakota Water Science Center Web site at:
http://nd.water.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:

Ryberg, K.R., 2008, PFReports: A program for systematic checking of annual peaks in NWISWeb: U.S. Geological Survey Open-File Report 2008–1284, 17 p.



Contents

Introduction

Limitations

Data

Qualification Codes

Process Overview

Tests

Information Reports

Computer Code

Summary

References Cited


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