Publications—Open-File Report 2007-1122

Prepared in cooperation with the Federal Emergency Management Agency

Flood of May 2006 in New Hampshire

By Scott A. Olson

 

U.S. Geological Survey Open-File Report 2007-1122

The body of the report is available in PDF Format (2,429 KB)

ONLINE ONLY


Abstract

From May 13–17, 2006, central and southern New Hampshire experienced severe flooding caused by as much as 14 inches of rainfall in the region. As a result of the flood damage, a presidential disaster declaration was made on May 25, 2006, for seven counties—Rockingham, Hillsborough, Strafford, Merrimack, Belknap, Carroll, and Grafton. Following the flooding, the U.S. Geological Survey, in a cooperative investigation with the Federal Emergency Management Agency, determined the peak stages, peak discharges, and recurrence-interval estimates of the May 2006 flood at 65 streamgages in the counties where the disaster declaration was made. Data from flood-insurance studies published by the Federal Emergency Management Agency also were compiled for each streamgage location for comparison purposes.

The peak discharges during the May 2006 flood were the largest ever recorded at 14 long-term (more than 10 years of record) streamgages in New Hampshire. In addition, peak discharges equaled or exceeded a 100-year recurrence interval at 14 streamgages and equaled or exceeded a 50-year recurrence interval at 22 streamgages. The most severe flooding occurred in Rockingham, Strafford, Merrimack, and eastern and northern Hillsborough Counties.

Contents

Abstract

Introduction

Description of Study Area

Storm Characteristics

Peak-Stage Data

Peak-Discharge Data

Flow-Frequency Analyses of the May 2006 Flooding

Comparison of the May 2006 Flood Data to Flood-Insurance Studies

Summary

Acknowledgments

Selected References

Figures

  1. Screenshot showing the 7-day precipitation totals ending on May 18, 2006, northeastern United States.

2–3. Maps showing:

  2A. Location of streamgages having peak stage and discharge data for the May 2006 flooding in Hillsborough County, New Hampshire.
  2B. Location of streamgages having peak stage and discharge data for the May 2006 flooding in Rockingham County, New Hampshire.
  2C. Location of streamgages having peak stage and discharge data for the May 2006 flooding in Merrimack County, New Hampshire.
  2D. Location of streamgages having peak stage and discharge data for the May 2006 flooding in Belknap County, New Hampshire.
  2E. Location of streamgages having peak stage and discharge data for the May 2006 flooding in Strafford County, New Hampshire.
  2F. Location of streamgages having peak stage and discharge data for the May 2006 flooding in Grafton County, New Hampshire.
  2G. Location of streamgages having peak stage and discharge data for the May 2006 flooding in Carroll County, New Hampshire.
  3. Recurrence intervals of the May 2006 flood at streamgages in Hillsborough, Rockingham, Merrimack, Belknap, Strafford, Grafton, and Carroll Counties in central and southern New Hampshire.

Tables

  1. Description of streamgages used to characterize the floods of May 2006 in central and southern New Hampshire.
  2. Peak-stage data and peak-discharge data for the flooding in May 2006 at 65 streamgages in central and southern New Hampshire.
  3. Flow-frequency data and recurrence interval estimates of the May 2006 flood for 65 streamgages in central and southern New Hampshire.
  4. Relation of computed May 2006 flood discharge and stage data to flood-insurance study data for selected streamgages in central and southern New Hampshire.

Suggested Citation

Olson, S.A., 2007, Flood of May 2006 in New Hampshire: U.S. Geological Survey Open-File Report 2007–1122, 32 p.


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For further information, contact:

Director
U.S. Geological Survey
New Hampshire-Vermont Water Science Center
361 Commerce Way
Pembroke, NH 03275

dc_nh@usgs.gov

(603) 226-7807

or visit our Web site at: http://nh.water.usgs.gov


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