Sensors placed in basements on historic property offer critical insight

Monday, February 19, 2024
Flooding at Strawbery Banke in Portsmouth

Flooding at the Strawbery Banke Museum property from a January 2024 storm was among the worst seen thus far. (Photo courtesy of Strawbery Banke Museum)

Rising sea levels and more frequent flooding have combined to become an increasingly alarming challenge for the in Portsmouth, where basements on this historic property are now routinely threatened by groundwater intrusion during events like King Tides and storm surges.

易胜博官网 researchers are playing a key role in helping Strawbery Banke formulate a plan to combat those challenges, having placed sensors in several basements and the nearby Piscataqua River that provide critical data to decision-makers at the museum and the city of Portsmouth.

With a couple of clicks of a mouse and taps on a keyboard from his desk in Morse Hall, Michael Routhier, researcher at 易胜博官网鈥檚 , can see virtually real-time data on water levels in some of the basements at Strawbery Banke, measuring things like salinity levels and temperature, as well.

Being able to monitor that information essentially on-demand provides a fuller picture of what is happening now and an opportunity to better predict what might need to take place in the future to preserve the iconic structures.听

Flooding at Strawbery Banke in Portsmouth

鈥淲e鈥檙e looking to see how much flooding is occurring in these basements and how that flooding is affecting the overall fabric of the buildings. This can include the actual deterioration of the foundation from the water coming in, as well as things like humidity rotting wood and rusting fasteners,鈥 Routhier says. 鈥淜nowing what these measurements are allows the decision-makers to have a better sense of how to mitigate or adapt to what has been happening and what鈥檚 coming down the road.鈥

易胜博官网鈥檚 quest to help Strawbery Banke combat these challenges dates back to 2012, Routhier says, when water sensors were initially placed in a few basements and wells were drilled in the green space in front of the museum鈥檚 visitor center.

But those sensors weren鈥檛 transmitting wireless information, meaning researchers had to go back every couple of weeks to pull the sensors out of the wells and plug them into a laptop to receive and review the data.

Advancements in technology have since made it possible to place sensors with cell phones attached that can push data directly to the cloud, and Routhier and his team have built an interface where it is possible to watch water levels go up and down on a feed that receives data every five minutes.

Those newer sensors were placed in two buildings on the property 鈥 the Shapley, Pridham House and the Jones House 鈥 in early 2023, and another was added in the nearby Piscataqua River around Thanksgiving 2023.

鈥淲e suspected back in 2012 when we put the first sensors in that flooding was related to the tidal patterns in the river, but now that we put in the new sensors, we鈥檙e able to see the relationship between the tidal patterns in the river and what is happening in the basements, live,鈥 Routhier says. 鈥淎nd what we鈥檙e able to tell is that there is approximately a half-hour delay between when we hit high tide in the river and when the water pressure pushes the water table up into the basement of the closest house.鈥

鈥淜nowing what these measurements are allows the decision-makers to have a better sense of how to mitigate or adapt to what has been happening and what鈥檚 coming down the road.鈥

Those learnings have been important, as it鈥檚 now possible for Rodney Rowland, director of facilities at Strawbery Banke, to see when water is rising in the nearby Piscataqua River, quickly alerting him that they might see basement flooding in the next 30 minutes or so.

What has become readily apparent is that incidents of groundwater inundation are happening more frequently and the flooding is becoming more severe. A recent round of rain in January produced the highest numbers Routhier has seen recorded thus far, and Rowland anecdotally noted he鈥檇 never seen flooding as bad at the Strawbery Banke campus.

鈥淚t鈥檚 good timing that we have these sensors out there now, because they are providing evidence as to what鈥檚 happening currently and what could happen in the long run 鈥 the inundation numbers are getting bigger and more frequent,鈥 Routhier says. 鈥淎nd the city of Portsmouth is really interested in what鈥檚 happening, too, because what鈥檚 happening at Strawberry Banke has an impact on the future of the city as well.鈥

How to manage that impact is the biggest challenge ahead, and a big part of what the data being collected will help inform. The Penhallow House at Strawberry Banke recently had to be raised more than 10 feet off the ground so a new foundation with advanced drainage could be built 鈥 a last resort for a property focused on historical preservation 鈥 and it鈥檚 possible that similar updates will be needed to other buildings on the property.

There is also talk of building a retention pond in green space on the property to help pull some of the groundwater away from the houses.

As those solutions are considered, Routhier says he鈥檚 excited that 易胜博官网 can be involved in a project with such significant impact that could potentially shape the future of the surrounding city.

鈥淚 think it鈥檚 great from multiple perspectives,鈥 Routhier says. 鈥淔rom the community engagement perspective because of Strawberry Bank鈥檚 link to our coastal cultural heritage, from a science perspective, because of how rising sea levels and increased frequency of storms is not just a local issue but a regional to global issue as well, and from a policy perspective because of how we can use cutting edge technologies to better inform decisions that will help our communities survive and thrive.鈥