Faculty Sponsor(s)

Jason Cordeira

Location

Hartman Union Building Courtroom

Presentation Type

Event

Start Date

5-3-2018 2:00 PM

End Date

5-3-2018 3:00 PM

Abstract

Ice jams and their floods occur during winter and spring in the northeastern U.S. and can have locally high impacts. A high-impact ice jam flood formed on the Pemigewasset River between Ashland and Plymouth on 26 February 2017. The rain from the cold front combined with precursor above freezing temperatures and a deep ripening snowpack to produce enhanced streamflow, ice break-up, damming, and flooding in Holderness that resulted in dozens of Plymouth State University students losing their vehicles. The first two weeks of February in featured below freezing temperatures and a series of heavy snowfall events in New Hampshire that led to frozen rivers and a deep snowpack. A large-scale regime transition by mid-February resulted in temperatures exceeding 10°C above normal during 18–25 February, which ripened the snowpack and led to total snow-water equivalent losses >10 cm over the Pemigewasset watershed. In the six hours leading up to the cold frontal passage, deep-moist southerly flow and snow-to-rain melting levels at 2000–2200 m were present over the region. The 3–5 cm of rainfall associated with the cold front in addition to the increased snowmelt led to the enhanced streamflow, ice dam, and flooding on the Pemigewasset River.

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May 3rd, 2:00 PM May 3rd, 3:00 PM

A Multiscale Analysis of an Ice Jam Flood on the Pemigewasset River in Central New Hampshire on 26 February 2017

Hartman Union Building Courtroom

Ice jams and their floods occur during winter and spring in the northeastern U.S. and can have locally high impacts. A high-impact ice jam flood formed on the Pemigewasset River between Ashland and Plymouth on 26 February 2017. The rain from the cold front combined with precursor above freezing temperatures and a deep ripening snowpack to produce enhanced streamflow, ice break-up, damming, and flooding in Holderness that resulted in dozens of Plymouth State University students losing their vehicles. The first two weeks of February in featured below freezing temperatures and a series of heavy snowfall events in New Hampshire that led to frozen rivers and a deep snowpack. A large-scale regime transition by mid-February resulted in temperatures exceeding 10°C above normal during 18–25 February, which ripened the snowpack and led to total snow-water equivalent losses >10 cm over the Pemigewasset watershed. In the six hours leading up to the cold frontal passage, deep-moist southerly flow and snow-to-rain melting levels at 2000–2200 m were present over the region. The 3–5 cm of rainfall associated with the cold front in addition to the increased snowmelt led to the enhanced streamflow, ice dam, and flooding on the Pemigewasset River.