Publications—Scientific Investigations Report

In cooperation with the New Jersey Department of Environmental Protection

Streamflow Characteristics and Trends in New Jersey, Water Years 1897-2003

By Kara M. Watson, Robert G. Reiser, Steven P. Nieswand, and Robert D. Schopp

U.S. Geological Survey Scientific Investigations Report 2005-5105

The body of the report is available in PDF Format (29,581 KB)

Streamflow statistical data in tables are available in PDF Format ( 10,632 KB)


Streamflow statistics were computed for 111 continuous-record streamflow-gaging stations with 20 or more years of continuous record and for 500 low-flow partial-record stations, including 66 gaging stations with less than 20 years of continuous record. Daily mean streamflow data from water year 1897 through water year 2001 were used for the computations at the gaging stations. (The water year is the 12-month period, October 1 through September 30, designated by the calendar year in which it ends). The characteristics presented for the long-term continuous-record stations are daily streamflow, harmonic mean flow, flow frequency, daily flow durations, trend analysis, and streamflow variability.

Low-flow statistics for gaging stations with less than 20 years of record and for partial-record stations were estimated by correlating base-flow measurements with daily mean flows at long-term (more than 20 years) continuous-record stations. Instantaneous streamflow measurements through water year 2003 were used to estimate low-flow statistics at the partial-record stations. The characteristics presented for partial-record stations are mean annual flow; harmonic mean flow; and annual and winter low-flow frequency.

The annual 1-, 7-, and 30-day low- and high-flow data sets were tested for trends. The results of trend tests for high flows indicate relations between upward trends for high flows and stream regulation, and high flows and development in the basin. The relation between development and low-flow trends does not appear to be as strong as for development and high-flow trends.

Monthly, seasonal, and annual precipitation data for selected long-term meteorological stations also were tested for trends to analyze the effects of climate. A significant upward trend in precipitation in northern New Jersey, Climate Division 1 was identified. For Climate Division 2, no general increase in average precipitation was observed. Trend test results indicate that high flows at undeveloped, unregulated sites have not been affected by the increase in average precipitation.

The ratio of instantaneous peak flow to 3-day mean flow, ratios of flow duration, ratios of high-flow/low-flow frequency, and coefficient of variation were used to define streamflow variability. Streamflow variability was significantly greater among the group of gaging stations located outside the Coastal Plain than among the group of gaging stations located in the Coastal Plain.





Purpose and Scope

Description of Study Area

Previous Investigations

Methods of Study

Continuous-Record Streamflow-Gaging Stations

Flow-Duration Analysis

Harmonic Mean Flow

Frequency Analysis

Trend Analysis

Streamflow Variability

Partial-Record Stations

Streamflow Characteristics

Flow Statistics

Streamflow Variability

Trends in Streamflow

Comparison of Trends in Precipitation to Trends in Flow at Undeveloped Sites

Trends in Peak Ratio at Selected Streamflow-Gaging Stations

Estimates of Low-Flow Statistics at Ungaged Sites

Ungaged Sites on Streams with Streamflow Data and No Regulation

Ungaged Sites on Streams with Streamflow Data and Regulation

Ungaged Sites on Streams with No Streamflow Data and No Regulation

Ungaged Sites Downstream from a Permitted Point Source

Summary and Conclusions

Literature Cited

Appendix 1. Indexes of selected continuous-record streamflow-gaging stations, low-flow partial-record stations, and gaging stations analyzed as partial-record stations in New Jersey

Appendix 2. Locations of streamflow-gaging stations by Watershed Management Areas

Appendix 3. Results of trend tests on annual n-day low and high flow at 138 gaging stations in New Jersey

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For further information, contact:


Richard Kropp, Director

U.S. Geological Survey

New Jersey Water Science Center

810 Bear Tavern Road Suite 206

Trenton, NJ 08628


(609) 771-3900


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