Scientists are studying changes in New Hampshire‘s rivers and streams after periods of heavy rain. The year 2023 will be remembered for incessant rains and frequent floods. “We saw about 100 flash floods in the state of New Hampshire in 2023,” said Sarah Jamison, senior hydrologist with the National Weather Service. “Over the last decade before, we had about 150 total.” While that could have been a fortuitous year, 2023 could be a sign of future changes in precipitation patterns. Warmer weather could lead to more frequent and intense rain showers in New England.>> Download the free KeynoteUSA app for updates on the go: Apple | Google Play <<"There was a feedback loop where the wet pattern we were in kept feeding over and over again," Jamison said. She said last year's heavy rain and flooding was the result of a weather pattern that resulted from a stronger summer. The boy. "If we look at the year 2023 in isolation, much of the credit or blame goes to El Niño, but we cannot ignore the influence of the warming climate," Jamison said. The Pemigewasset River in Plymouth is one of many New England Rivers that were severely affected by recent flooding. Scientists are studying changes to New Hampshire's rivers and how they could affect communities along them. To track changing water conditions, Rick Kiah and his team at the New England Water Sciences Center take measurements with 60 gauges in rivers. throughout New Hampshire. Measurements include river height and stream flow, a measure of how much water is moving in a particular area. "We transmit it over the GOES satellite system in real time, so our other federal partners, like the Weather Service, can capture that data and make forecasts," Kiah said. Then Rob Dudley, supervising hydrologist at the New England Water Sciences Center, studies that data and has investigated climate-related trends in New England watersheds for more than two decades. "We have definitely seen trends in the increase of rainfall," he said. "Overall, we've really been seeing larger magnitudes in those more frequent floods." According to Climate Central, the Northeast has seen, on average, about a 60% increase in heavy precipitation since the late 1950s. Along with precipitation, temperatures play a major role in changing river conditions. . "We've been seeing later ice formation and then earlier ice calving on the rivers," Dudley said. Winter is the fastest warming season in New Hampshire. Dudley said this will likely have an impact on the way rivers flood in the future. "With less ice, the expectation is that there will be fewer ice jams that would contribute to flooding," he said. "And yet, there are more rain-on-snow events." While increased flooding is not expected to make flooding worse, it could increase the rate of erosion. "If there is a change in the flow regime and the water transports and deposits sediment, and if its character changes over time, it will certainly have some effects on the form and function of the river," Dudley said. That is a concern for many. homes and businesses along the New Hampshire coast. Some Granite State rivers have records dating back more than a century. Having such a long record of information helps scientists determine the conditions necessary for a. future major flooding. "With the historical record that we collect, we can adjust what that flood level is, and then that will translate into our flood insurance rate. maps to help with sustainable building in the future," Dudley said. The data being collected in New England should help forecasters better manage increased flooding. The next step, experts said, is to build the resilience of vulnerable communities.
PLYMOUTH, New Hampshire—
Scientists are studying changes in New Hampshire’s rivers and streams after periods of heavy rain.
The year 2023 will be remembered for incessant rains and frequent floods.
“We saw about 100 flash floods in the state of New Hampshire in 2023,” said Sarah Jamison, senior hydrologist with the National Weather Service. “Over the last decade before, we had about 150 total.”
While that could have been a fortuitous year, 2023 could be a sign of future changes in precipitation patterns. Warmer weather could lead to more frequent and intense rainfall in New England.
>> Download the free KeynoteUSA app to get updates on the go: apple | Google Play <
“There was a feedback loop where the wet pattern we were in kept feeding over and over again,” Jamison said.
He said last year’s heavy rains and flooding were the result of a weather pattern that resulted from a stronger El Niño summer.
“If we look at the year 2023 in isolation, much of the credit or blame goes to El Niño, but we cannot ignore the influence of the warming climate,” Jamison said.
The Pemigewasset River in Plymouth is one of many New England rivers that were severely affected by recent flooding. Scientists are studying changes to New Hampshire’s rivers and how they could affect communities along them.
To track changing water conditions, Rick Kiah and his team at the New England Water Sciences Center take measurements with 60 gauges in rivers throughout New Hampshire.
Measurements include river height and stream flow, a measure of how much water is moving in a particular area.
“We transmit it through the GOES satellite system in real time, so our other federal partners, like the Weather Service, can capture that data and make forecasts,” Kiah said.
That data is then studied by Rob Dudley, supervising hydrologist at the New England Water Sciences Center, who has investigated climate-related trends in New England watersheds for more than two decades.
“We’ve definitely seen trends in increased precipitation,” he said. “Overall, we’ve been seeing larger magnitudes in those more frequent floods.”
According to Climate Central, the Northeast has seen, on average, about a 60% increase in heavy precipitation since the late 1950s. Along with precipitation, temperatures play a major role in changing river conditions. .
“We’ve been seeing later ice formation and then earlier ice calving on the rivers,” Dudley said.
Winter is the fastest warming season in New Hampshire. Dudley said this will likely have an impact on how rivers overflow in the future.
“With less ice, the expectation is that there will be fewer ice jams that would contribute to flooding,” he said. “And yet, there are more rain-on-snow events.”
While increased flooding is not expected to make flooding worse, it could increase the rate of erosion.
“If there is a change in the flow regime and the water transports and deposits sediment, if the character of that changes over time, it will certainly have some effects on the form and function of the river,” Dudley said. .
That’s a concern for many homes and businesses along New Hampshire’s waterways. Some rivers in the Granite State have records dating back more than a century. Having such a long record of information helps scientists determine the conditions necessary for a future major flood.
“With the historical record that we collect, we can adjust what the flood level is and then that will be translated into our flood insurance rate maps to help with sustainable building in the future,” Dudley said.
The data being collected in New England should help forecasters better manage increased flooding. The next step, experts said, is to build the resilience of vulnerable communities.
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