21-4 THE COLD RIVER AND ITS ADAPTATION TO RECENT EXTREME PRECIPITATION EVENTS

Session: Functions of River Corridors, Floodplains and Wetlands (Posters)

Presenting Author:

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Abstract:

Flooding is a disaster that causes the U.S around 180-460 billion dollars every year. The Cold River located in southwestern New Hampshire is a river that has experienced three high magnitude flood events over the past 30 years, (2005, 2021, and 2023) placing financial strain on local communities. This study focuses on the response of the Cold River to climate change. With climate changing, extreme precipitation events are becoming more frequent and with it, more flooding. Historic changes in flow are recorded in data measured at the Drewsville (1940-1978) and Alstead (2009 to present) gages. The river is becoming increasingly flashy with higher extreme flows and lower low flows.  Flood events that historically occurred in the Spring are less frequent whereas Summer and Fall events are becoming more common. The area under investigation is a 1000-meter, unconfined, bedload dominated reach of the river in South Acworth, NH, near its confluence with Milliken Brook.  Channel changes were documented using a variety of imagery, including four years of drone imagery extending from 2019 to 2024, and field observations.  The last two flood events (2021 and 2023) resulted in channel widening, anabranching, channel avulsion, and increased sinuosity.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

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