Simulated and observed 2010 floodwater elevations in the Pawcatuck and Wood Rivers, Rhode Island

Scientific Investigations Report 2013-5193
Prepared in cooperation with the U.S. Department of Homeland Security-Federal Emergency Management Agency
By: , and 

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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.

Study Area

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Simulated and observed 2010 floodwater elevations in the Pawcatuck and Wood Rivers, Rhode Island
Series title Scientific Investigations Report
Series number 2013-5193
DOI 10.3133/sir20135193
Year Published 2014
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) New England Water Science Center
Description Report: v, 24 p.; 1 Excel document; 1 Appendix
Country United States
State Rhode Island
Other Geospatial Pawcatuck River;Wood River
Datum North American Datum 1983
Projection Rhode Island State Plane Projection
Scale 24000
Online Only (Y/N) Y
Additional Online Files (Y/N) Y