DR. TOM BALLESTERO, University of New Hampshire professor, a hydrologist and water resources engineer, offered an overview of the trends and effects of warming observed by scientists over several decades and steps to mitigate those changes for our children and grandchildren at the Wolfeboro Water Summit in the Great Hall on May 13. (Elissa Paquette photo) (click for larger version)
May 25, 2017WOLFEBORO — Wentworth Watershed Association President Anne Blodget opened the Wolfeboro Water Summit on May 13 in the Great Hall before a packed hall. The intent of the summit, said Blodget, was to "build combined understanding and work toward community based solutions" in response to threats to the the water resources that are "our livelihood economically and emotionally."
University of New Hampshire professor Dr. Tom Ballestero, a hydrologist and water resources engineer, the first of the speakers and panelists to speak, offered an overview of the trends and effects of warming observed by scientists over several decades and steps to mitigate those changes for our children and grandchildren.
"Infrastructure we design today can't be static. We have to think about what's going to happen 100 years from now," said Ballestero.
It probably doesn't surprise those of us living in New England that snow cover has been decreasing. The mean averages are trending downward. But it's the standard deviations that have attracted special attention. They are becoming wider. We have years with no snow, years with a phenomenal amount. Precipitation is decreasing in some areas of the country and increasing in others.
This past year's drought, which caused some wells to dry out, is an example of an extreme variation with adverse effects, including economic impact.
Here in New England, there is more winter rain than snow, an earlier melting of the snow pack, more stream flow in March and April, and less in May, June and July, noted Ballestero. The flora and fauna have to adapt to survive.
In New Hampshire, said Ballestero, looking at data post 1970, what is considered a 100 year flood has increased 40 percent. In his view, that should cause us to rethink our policies. For instance, flood insurance compensates its policy holders in order to rebuild on the same spot. "Our children and grandchildren could be in a flood plain...Are we going to keep doing this?" he asked.
He pointed out that the Lamprey River in Newmarket has had 11 one hundred year floods in the last 25 years. Ten of those occurred in the last 15 years, and seven in the last five years.
What do these changes mean for infrastructure? Most of our infrastructure was built when Baby Boomers were coming of age, with a common design life of 20 to 50 years, said Ballestero. The consequences of changes in weather patterns needs to be taken into account, looking out to 2040 and on to 2070.
There's been a switch from snowmelt hydrology to runoff hydrology, especially in larger watersheds. Designs have to accommodate higher design flows, more runoff volume, increased sediment transport, increased hydraulic attack on structures and expanding wetlands. Species that can't get out of the way, those at the bottom of the food chain, won't survive.
Bridges will need greater height. Using the Piscataqua River bridge as an example, Ballastero said ships will have to come in at low tide, which entails dredging the channels.
Design standards and codes need to change, he asserted, to protect transportation routes and newly endangered species.
A You Tube video of the Water Summit is on line, at the Wolfeboro Community Television website. Next week's article on the event will feature Don Kretchmer's presentation: Wolfeboro Water Resources and Challenges.