Open-File Report 2008–1203

Prepared in cooperation with Federal Emergency Management Agency

Flood Magnitude and Frequency of the Delaware River in New Jersey, New York, and Pennsylvania

By Robert D. Schopp and Gary D. Firda

Open-File Report 2008–1203

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From September 2004 to June 2006, the Delaware River in New Jersey, New York, and Pennsylvania experienced three major floods that caused extensive damage. The Federal Emergency Management Agency (FEMA) needed updated information on the flood magnitude and frequency for the eight active streamflow-gaging stations along the main stem Delaware River in New Jersey, New York, and Pennsylvania that included the three recent floods in order to update its flood insurance studies. Therefore, the U.S. Geological Survey (USGS) computed updated flood magnitude and frequency values following the guidelines published by the Interagency Advisory Committee on Water Data in its Bulletin 17B. The updated flood-frequency values indicate that the recurrence interval of the September 2004 flood ranged from 20 to 35 years, the recurrence interval of the April 2005 flood ranged from 40 to 70 years, and the recurrence interval of the June 2006 flood ranged from 70 to greater than 100 years. Examination of trends in flood discharges indicate no statistically significant trends in peak flows during the period of record for any of the eight streamflow-gaging stations.




Description of Study Area

Streamflow Data

Trend Analysis

Flood Magnitude and Frequency Computation



References Cited


1. Map showing location of U.S. Geological Survey streamflow-gaging stations on the Delaware River.

2. Plot showing annual flood peaks recorded on the Delaware River at Trenton, N.J., water years 1898-2006.


1. Streamflow-gaging stations on the main stem Delaware River.

2. Change in estimated forest cover for selected locations along the Delaware River, 1894 to 1992.

3. Flood magnitude and frequency for streamflow-gaging stations on the main stem Delaware River.

Download: PDF of OFR2008–1203 (1.3 Mb)

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