By Cole Caviston, Staff Writer
Spring may not be until March 20, but the signs of its approach are visible across campus as the snow mounds of recent winter storms slowly melt away.
According to the National Oceanic and Atmospheric Administration (NOAA), the amount of water contained the snow packs across Durham is believed to be 8 inches.
Jennifer Jacobs, a professor of civil and environmental engineering, believes the amount of water would be a factor for potential flooding.
“If that melted pretty rapidly, that’s enough to have a pretty sizeable flooding event, particularly to put a little bit of rain of top of it,” Jacobs said.
But both Jacobs and Anne Lightbody, an assistant professor of Earth science, agree that the most disastrous floods in New Hampshire are the results of heavy rain rather than snowmelt.
“Floods have become more frequent over the last few decades due to increased construction of parking lots and buildings, which prevent precipitation from infiltrating into the ground,” Lightbody said. “Flood frequencies have also increased because intense rain storms have become more common.”
According to Lightbody, about two-thirds of precipitation evaporates back into the atmosphere on an annual basis before it runs off into streams and rivers. If the ground receives warm rain before the snow melts, that rain will not make its way into the ground, but rather would melt “large quantities of snow.”
“Therefore, most of the water in the current snow packs will either infiltrate into the ground, once the ground melts, or run off into the streams that drain campus,” Lightbody said.
Low-lying areas close to streams and rivers are at the most risk from flooding.
Stream banks under buildings can become eroded, basements can become filled with water and roadways can become obstructed.
“Warm spring temperatures and cool spring nights lead to daytime melting and night-time freezing, which can create black ice on sidewalks and roadways,” Lightbody said.
Flooding can also result in the spreading of outdoor substances to water sources, which increases the potential for pollution.
“Melting snow will wash all of the sand and salt placed all winter on sidewalks and roads into your streams, rivers, and groundwater,” Lightbody said. “Melting snow can also transport road oil, lawn chemicals and trash into our water.”
However, warm spring temperatures can reduce the risk of flooding due to the amount of time it takes for streams to transport water away and for water to infiltrate into the ground.
“If we receive rain before the ground melts, then flooding may occur, since the rain will not be able to infiltrate into the frozen ground, and the warm rain will help to suddenly melt larger quantities of snow,” Lightbody said.
Another source of flooding, according to Jacobs, is the possibility that the ice in the streams and rivers could break up and serve as natural dams.
However, Jacobs is confident that the risk of flooding this year on campus will be minimal.
“There doesn’t tend to be a tremendous amount of flooding on campus,” Jacobs said.
According to Jacobs, the only place on campus that has flooded in “extreme events” has been the College Brook. In the past, coastal New Hampshire has experienced only two major floods: in May 2006 on Mother’s Day and in April 2007 on Patriot’s Day.
“Both were classified as ‘100-year floods’, which means that the probability of occurrence is less than 1 percent in any year,” Lightbody said. “It is very rare, though not impossible, to have two such large events so close together.”
A statement issued by the National Weather Service on March 6 said that any short term flooding in western Maine and New Hampshire over the next two weeks would be normal.
“It is important to note that the major flooding does not occur from snow melt alone,” the statement reads. “Rainfall … is the most important factor in determining the severity of flooding.”
The National Weather Service also stated that the potential for longer-term flooding and ice jams is “above normal.”