By Scott A. Olson
U.S. Geological Survey Open-File Report 2006-1221
The body of the report is available in PDF Format ( 36,677 KB)
Southwestern New Hampshire experienced damaging flooding on October 8 and 9, 2005. The flooding was the result of a storm producing at least 7 inches of rain in a 30-hour period. The heavy, intense rainfall resulted in runoff and severe flooding, especially in regions of steep topography that are vulnerable to flash flooding. Some of the worst property damage was in the towns of Alstead, Langdon, and Walpole, New Hampshire along Cold River and Warren Brook. Warren Brook was severely flooded and had flows that exceeded a 100-year recurrence interval upstream of Cooper Hill Road. Downstream of Cooper Hill Road, the flooding was worsened as a result of a sudden release of impounded water, making the flood levels greater than what would be experienced from a 500-year recurrence-interval flood.
Along Cold River, upstream of its confluence with Warren Brook, flooding was at approximately a 100-year recurrence interval. Downstream of the confluence of Cold River and Warren Brook, the streamflows, which were swollen by the surge of water from Warren Brook, exceeded a 500year recurrence interval.
Description of Investigated Reaches
Warren Brook at Mill Hollow
Warren Brook Downstream of Cooper Hill Road
Cold River at Vilas Pool Dam
Cold River Downstream of the Warren Brook Confluence
Cold River at the Drewsville USGS Stream-Gaging Station
1–2. Maps showing—
4–5. Graphs showing—
|4.||Flood-flow frequency estimates for selected recurrence intervals at selected sites on Warren Brook, Alstead, NH.|
|5.||Flood-flow frequency estimates for selected recurrence intervals at selected sites on Cold River, Alstead, Langdon, and Walpole, NH.|
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For further information, contact:
Keith W. Robinson, Director
U.S. Geological Survey
New Hampshire - Vermont Water Science Center
361 Commerce Way
Pembroke , NH 03275
(603) 226-7807or visit our Web site at: http://nh.water.usgs.gov