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Scientific Investigations Report 2013–5193

Prepared in cooperation with the U.S. Department of Homeland Security-Federal Emergency Management Agency

Simulated and Observed 2010 Floodwater Elevations in the Pawcatuck and Wood Rivers, Rhode Island

By Phillip J. Zarriello, David E. Straub, and Thor E. Smith

Thumbnail of and link to report PDF (9.89 MB)Abstract

Heavy, persistent rains from late February through March 2010 caused severe flooding that set, or nearly set, peaks of record for streamflows and water levels at many long-term U.S. Geological Survey streamgages in Rhode Island. In response to this flood, hydraulic models of Pawcatuck River (26.9 miles) and Wood River (11.6 miles) were updated from the most recent approved U.S. Department of Homeland Security-Federal Emergency Management Agency flood insurance study (FIS) to simulate water-surface elevations (WSEs) for specified flows and boundary conditions. The hydraulic models were updated to Hydrologic Engineering Center-River Analysis System (HEC-RAS) using steady-state simulations and incorporate new field-survey data at structures, high resolution land-surface elevation data, and updated flood flows from a related study.

The models were used to simulate the 0.2-percent annual exceedance probability (AEP) flood, which is the AEP determined for the 2010 flood in the Pawcatuck and Wood Rivers. The simulated WSEs were compared to high-water mark (HWM) elevation data obtained in a related study following the March–April 2010 flood, which included 39 HWMs along the Pawcatuck River and 11 HWMs along the Wood River. The 2010 peak flow generally was larger than the 0.2-percent AEP flow, which, in part, resulted in the FIS and updated model WSEs to be lower than the 2010 HWMs. The 2010 HWMs for the Pawcatuck River averaged about 1.6 feet (ft) higher than the 0.2-percent AEP WSEs simulated in the updated model and 2.5 ft higher than the WSEs in the FIS. The 2010 HWMs for the Wood River averaged about 1.3 ft higher than the WSEs simulated in the updated model and 2.5 ft higher than the WSEs in the FIS. The improved agreement of the updated simulated water elevations to observed 2010 HWMs provides a measure of the hydraulic model performance, which indicates the updated models better represent flooding at other AEPs than the existing FIS models.

First posted January 24, 2014

For additional information, contact:
Office Chief, New England Water Science Center
U.S. Geological Survey
Massachusetts-Rhode Island Office
10 Bearfoot Road
Northborough, MA 01532
(508) 490-5000

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Suggested citation:

Zarriello, P.J., Straub, D.E., and Smith, T.E., 2014, Simulated and observed 2010 floodwater elevations in the Pawcatuck and Wood Rivers, Rhode Island: U.S. Geological Survey Scientific Investigations Report 2013–5193, 24 p.,

ISSN 2328-0328 (online)




Hydraulic Models

Comparison of 2010 Flood High-Water Marks With Simulated Water Levels

Summary and Conclusions

References Cited

Appendix 1. Pawcatuck River and Wood River Hydraulic Models: Technical Support Data Notebook

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