Flood-inundation maps for the Hoosic River, North Adams and Williamstown, Massachusetts, from the confluence with the North Branch Hoosic River to the Vermont State line

Scientific Investigations Report 2014-5236
Prepared in cooperation with the Federal Emergency Management Agency
By:  and 

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Abstract

A series of nine digital flood-inundation maps were developed for an 8-mile reach of the Hoosic River in North Adams and Williamstown, Massachusetts, by the U.S. Geological Survey (USGS) in cooperation with the Federal Emergency Management Agency. The coverage of the maps extends from the confluence with the North Branch Hoosic River to the Vermont State line. Peak flows with 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities were computed for the reach from updated flood-frequency analyses. These peak flows were routed through a one-dimensional step-backwater hydraulic model to obtain the corresponding peak water-surface elevations, and to place the tropical storm Irene flood of August 28, 2011 into historical context. The hydraulic model was calibrated by using the current (2014) stage-discharge relation at the USGS streamgage Hoosic River near Williamstown, Massachusetts (01332500), and from documented high-water marks from the tropical storm Irene flood, which had approximately a 1-percent annual exceedance probability.

The hydraulic model was used to compute water-surface profiles for flood stages referenced to the streamgage and ranging from 9 feet (ft; 624.45 ft North American Vertical Datum of 1988 [NAVD 1988]), which is near bankfull, to 16.1 ft (631.59 ft NAVD 1988), which exceeds the maximum recorded water level at the streamgage and the National Weather Service major flood stage of 13.0 ft. The mapped stages, 10.9 to 16.1 ft, were selected to match the stages of flows with annual exceedance probabilities between 20 and 0.2 percent, and thus do not fall at exact 1-ft increments. The simulated water-surface profiles were combined with a geographic information system digital elevation model derived from light detection and ranging (lidar) data having a 0.5-ft vertical accuracy to create a set of flood-inundation maps.

The availability of the flood-inundation maps, combined with information regarding current (near real-time) stage from USGS streamgage Hoosic River near Williamstown, and forecasted flood stages from the National Weather Service Advanced Hydrologic Prediction Service will provide emergency management personnel and residents with information that is critical for flood response activities such as evacuations and road closures, and post-flood recovery efforts. The flood-inundation maps are nonregulatory, but provide Federal, State, and local agencies and the public with estimates of the potential extent of flooding during selected peak-flow events.

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Creation of Flood-Inundation Map Library
  • Summary
  • References Cited
  • Appendix 1. Water-Surface Elevations at Modeled Cross Sections Along the Hoosic River, North Adams and Williamstown, Massachusetts
  • Appendix 2. Shapefiles for the Hoosic River Study Reach in North Adams and Williamstown, Massachusetts, Including Flood Plain Boundaries for the 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-Percent Annual Exceedance Probability (AEP) Floods; the 1-Percent AEP Floodway; Model Cross Sections; and Water-Surface Elevations for the 1-Percent AEP Flood

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Flood-inundation maps for the Hoosic River, North Adams and Williamstown, Massachusetts, from the confluence with the North Branch Hoosic River to the Vermont State line
Series title Scientific Investigations Report
Series number 2014-5236
DOI 10.3133/sir20145236
Year Published 2015
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Maine Water Science Center
Description Report: vi, 15 p.; Downloads Directory
Country United States
State Massachusetts
County North Adams County, Williamstown County
Other Geospatial Hoosic River
Online Only (Y/N) Y
Additional Online Files (Y/N) Y
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