Pennsylvania Water Science Center


Dan Goode


Study Area Location (image DRBC) In cooperation with the
Delaware River Basin Commission (DRBC)

In collaboration with
U.S. Army Corps of Engineers, Hydrologic Engineering Center (HEC), and
NOAA's National Weather Service, Middle Atlantic River Forecast Center

Modeling recent flooding in the Delaware River

by Daniel J. Goode, Edward H. Koerkle, Joan D. Klipsch (HEC), and Amy L. Shallcross (DRBC)


Major flooding occurred in the Delaware River in September 2004, April 2005, and June 2006. U.S. Army Corps of Engineers (USACE) manages four reservoirs in the watershed for flood-loss reduction, and other reservoirs — designed and used primarily for water supply, recreation, low-flow augmentation, or hydropower — also attenuate streamflow. To evaluate the impact of reservoir levels and other factors on peak streamflow during those three storms, the Delaware River Basin Commission (DRBC), U.S. Geological Survey (USGS), USACE Hydrologic Engineering Center (HEC), and National Oceanic and Atmospheric Administration’s National Weather Service (NWS) developed a flood-analysis model. The States of Delaware, Pennsylvania, New Jersey, and New York provided support through DRBC. The flood-analysis model includes a rainfall-runoff part and a reservoir-operations part. The USGS Precipitation Runoff Modeling System (PRMS) simulates reservoir inflow and runoff throughout the 6,780 square-mile watershed draining to the USGS streamgage at Trenton, N.J. PRMS was calibrated for the three high-flow events using automatic and manual procedures and hourly streamflow data from 35 USGS streamgages. NWS provided data and processing algorithms for the radar-based Multisensor Precipitation Estimate (MPE) and other support. USACE's HEC-ResSim simulates the operations of 13 reservoirs in the watershed and routes streamflow discharged from the reservoirs. Reservoir characteristics and operation information were provided by DRBC, USACE Philadelphia District, New York City Department of Environmental Protection, and private reservoir operators. Input runoff for HEC-ResSim is PRMS-modeled runoff, or optionally “gage-estimate” runoff. Gage-estimate runoff was based on observed unregulated streamflow where available and translation, scaling, and adjustment of those flows for ungaged areas. Model results using gage-estimate runoff closely match observed streamflow below the reservoirs, but only the three actual events with existing conditions can be simulated. The flood-analysis model is a planning tool for evaluation of alternative reservoir management on streamflow during floods. Using PRMS for simulation of runoff with HEC-ResSim additionally allows evaluation of the impact of changes to conditions such as impervious surface in the watershed, watershed conditions before the floods, or different climate.

Suggested Citation

Goode, D.J., Koerkle, E.H., Klipsch, J.D., and Shallcross, A.L., 2010, Modeling recent flooding in the Delaware River: (abs.) in Proc. 2010 AWRA Annual Water Resources Conference: American Water Resources Assoc, accessed online on February 11, 2011 at .

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