Selected Streamflow Statistics for Streamgage Locations in and Near Pennsylvania
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Prepared in cooperation with the Pennsylvania Department of Environmental Protection Selected Streamflow Statistics for Streamgage Locations in and near Pennsylvania Open-File Report 2011–1070 U.S. Department of the Interior U.S. Geological Survey Cover. Tunkhannock Creek and Highway 6 overpass downstream from U.S. Geological Survey streamgage 01534000 Tunkhannock Creek near Tunkhannock, PA. (Photo by Andrew Reif, USGS) Selected Streamflow Statistics for Streamgage Locations in and near Pennsylvania By Marla H. Stuckey and Mark A. Roland Prepared in cooperation with the Pennsylvania Department of Environmental Protection Open-File Report 2011–1070 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. 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Suggested citation: Stuckey, M.H., and Roland, M.A., 2011, Selected streamflow statistics for streamgage locations in and near Pennsyl- vania: U.S. Geological Survey Scientific Investigations Report 2011–1070, 88 p. iii Contents Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................1 Purpose and Scope ..............................................................................................................................1 Previous Investigations........................................................................................................................1 Data Collection and Analysis .......................................................................................................................2 Comparison with Previously Reported Streamflow Statistics for Streamgage Locations in Pennsylvania .....................................................................................................................................4 Summary..........................................................................................................................................................4 Acknowledgments .........................................................................................................................................4 References Cited............................................................................................................................................5 Figures 1. Map showing location of U.S. Geological Survey streamgage locations with updated streamflow statistics ....................................................................................................3 Tables 1. List of U.S. Geological Survey streamgage locations in and near Pennsylvania with updated streamflow statistics ...........................................................................................8 2. Selected low-flow statistics for streamgage locations in and near Pennsylvania .........20 3. Selected base-flow statistics for streamgage locations in and near Pennsylvania .......34 4. Selected flood-flow statistics for streamgage locations in and near Pennsylvania ......48 5. Selected mean-flow and flow-duration statistics for streamgage locations in and near Pennsylvania ..............................................................................................................60 6. Comparison of streamflow statistics for 72 streamgage locations in Pennsylvania to previously reported streamflow statistics .........................................................................88 iv Conversion Factors Inch/Pound to SI Multiply By To obtain Area square mile (mi2) 259.0 hectare (ha) square mile (mi2) 2.590 square kilometer (km2) Flow rate foot per second (ft/s) 0.3048 meter per second (m/s) cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s) cubic foot per second per square 0.01093 cubic meter per second per square mile [(ft3/s)/mi2] kilometer [(m3/s)/km2] Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88). Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83). Selected Streamflow Statistics for Streamgage Locations in and near Pennsylvania By Marla H. Stuckey and Mark A. Roland Abstract for Flood Insurance Studies (FIS), flood-plain manage- ment, and the design of bridges and flood-control structures. Streamflow statistics are used routinely by watershed Streamflow statistics for a streamgage can change over time planners, regulators, engineers, and managers for water- as more data become available or as land use or climate in resource projects. Streamflow statistics for a streamgage the watershed changes, so streamflow statistics should be can change over time as more flow data become available updated periodically. and (or) land use or climate in the watershed changes; con- sequently, streamflow statistics should be updated periodi- Purpose and Scope cally. This report, done in cooperation with the Pennsylvania Department of Environmental Protection, presents updated This report presents updated streamflow statistics for streamflow statistics for 526 U.S. Geological Survey (USGS) 526 U.S. Geological Survey (USGS) continuous-record continuous-record streamgages in Pennsylvania, New York, streamgage locations in and near Pennsylvania using data New Jersey, Delaware, Maryland, West Virginia, and Ohio collected through the 2008 water yeart. Streamgages from using data collected through 2008. The following statistics are Pennsylvania (306), New York (65), New Jersey (28), Dela- presented: low flows (1-day, 10-year; 7-day, 10-year; 7-day, ware (13), Maryland (68), West Virginia (21), and Ohio (25) 2-year; 30-day, 10-year; 30-day, 2-year; and 90-day, 10-year were included in this analysis. The following statistics are low flows), base flows (10-year, 25-year, and 50-year base presented: low flows (1-day, 10-year; 7-day, 10-year; 7-day, flows), peak flows (50-, 20-, 10-, 4-, 2-, 1-, and 0.2-percent 2-year; 30-day, 10-year; 30-day, 2-year; and 90-day, 10-year annual exceedance flood), mean flows (mean annual flow and low flows), base flows (10-year, 25-year, and 50-year base harmonic mean flow), and flow durations (99-, 95-, 90-, 85-, flows), peak flows (50-, 20-, 10-, 4-, 2-, 1-, and 0.2-percent 80-, 70-, 60-, 50-, 40-, 30-, 20-, 15-, 10-, 5-, and 1-percent annual exceedance flood), mean flows (mean annual flow and exceedance). Streamflow statistics (7-day, 10-year and 30-day, harmonic mean flow), and flow durations (99-, 95-, 90-, 85-, 10-year low flows; harmonic mean; and 95-, 50-, and 5-per- 80-, 70-, 60-, 50-, 40-, 30-, 20-, 15-, 10-, 5-, and 1- percent cent flow duration exceedances) for 72 streamgage locations exceedance). This development of updated streamflow statis- in Pennsylvania were compared using a Wilcoxon signed-rank tics was done in cooperation with the Pennsylvania Depart- test to previously reported statistics. A statistically significant ment of Environmental Protection (PaDEP). The selection difference was found between the data sets for the 30-day, of streamgage locations was determined by the need from 10-year low-flow; harmonic mean; 50-percent flow-duration PaDEP for updated streamflow information at reference sites exceedance; and 5-percent flow-duration exceedance statis- to assist in permit application review. Streamflow statistics for tics. No significant difference was found between the data streamgages in Pennsylvania will be displayed on the web- sets for the 7-day, 10-year low-flow and 95-percent flow- based application Pennsylvania StreamStats (Stuckey and duration exceedance statistics. The lower flow statistics show Hoffman, 2010). a decrease since 1996, and the mid- to higher flows show an increase since 1996. Previous Investigations Streamflow statistics for USGS streamgage locations in Introduction Pennsylvania have been published in many USGS reports. Stuckey (2006) developed low-flow, base-flow, and mean-flow Streamflow statistics are used routinely by watershed planners, regulators, engineers, and managers for water- resource projects. Low-flow statistics are used to determine 1 Water year is defined as a 12-month period beginning October 1 and end- water availability, water-use allocations, assimilative capaci- ing September 30. The water year is designated by the calendar year in which ties, and aquatic-habitat needs. Flood-flow statistics are used it ends. 2 Selected Streamflow Statistics for Streamgage Locations in and near Pennsylvania regression equations and reported statistics for 293 continu- post-regulation periods, when the period had at least 9 years of ous-record and partial-record streamgages using data through data.