Frequent Flooding: Climate change, development blamed for rapidly rising number of '100-year storms'

Merrimack Valley

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March 20, 2010

Climate change, development blamed for rapidly rising number of '100-year storms'

By J.J. Huggins and Jill Harmacinski

In their worst form, they were known as "100-year storms": catastrophes that occurred once a century and caused devastating floods.

And yet, in just the past four years, three times the Merrimack Valley and Southern New Hampshire have been hard-hit by storms that once came with interludes of decades between them.

The most recent deluge was last week, when residents of Andover and Lawrence were forced out of their homes as their properties became drenched and heavily damaged by the waters of the Spicket and Shawsheen rivers. In New Hampshire, residents of Salem and surrounding communities were also affected by the flooding.

A nor'easter dumped nearly 10 inches of rain on the Merrimack Valley from Saturday through Monday, creating scenes reminiscent of the Mother's Day floods of 2006 and their memorable encore in April 2007.

"It's becoming too common of an occurrence," said state Rep. Barry Finegold, D-Andover.

As officials tally the cost of the latest storm, people are wondering why these floods keep happening. And they want to know what, if anything, the region can do to prepare for the next onslaught.

Local environmental groups say the blame lies with a variety of culprits: development, outdated flood data, and beavers, to name a few.

It's not a case of more rain falling, officials say. Rather, storms are increasingly intense, and that's courtesy of climate change.

Mark Torres has watched this firsthand. The Methuen resident has lived on Armory Street for 10 years and dealt with three floods in that decade.

"Before I lived here, this place never got flooded," Torres said Monday, the swollen Merrimack River inching toward his home even as he spoke.

Storms of growing wrath

"While there has been little change in average rainfall, the amount of rain dropped during major storm events has increased dramatically," said Tennis Lilly, chairman of the Lawrence Conservation Commission.

Lilly explained that if you look at the Cornell Rainfall Atlas, the 20-, 50- and 100-year storms all produce much more rain than they did 40 years ago.

The term "100-year flood" is used in an attempt to simplify the definition of a flood that statistically has a 1 percent chance of occurring in any given year.

"A 50-year storm now produces what a 100-year storm did 40 years ago," Lilly said. "As for a '100-year storm,' add about 25 percent more rain in a 24-hour period and that's what you now get."

Bob Rauseo, president of the Shawsheen River Watershed Association, also says the intensity of storms has grown tremendously in the last 100 years. He points to records kept by the U.S. Geological Survey showing peak stream flow for the Shawsheen River in Wilmington, upstream from where last week's damage occurred in Andover.

The records, which cover 1964 to 2007, show that the annual peak stream flow reached 1,050 cubic feet per second in 1968. Then, however, they surpassed the 1,000 mark only twice in the following two decades — in 1979 and 1987.

Stream flow peaks of more than 1,000 cubic feet per second have become more frequent in the last two decades. The river peaked at 1,850 cubic feet per second in Wilmington in 1996, at 1,240 cubic feet per second in 1998, at 1,580 cubic feet per second in 2001, at 1,110 cubic feet per second in 2004 and at 1,210 cubic feet per second in 2006, according to the US Geological Survey.

Stream flow peaked at 1,710 cubic feet per second in Wilmington last Monday and at 1,610 cubic feet per second last Tuesday, according to the US Geological Survey.

"That is why storm drains and culverts get overwhelmed. They were designed to handle less volume than we now are seeing on a regular basis," Lilly said. "If you look at the general circulation models and the projected changes caused by global warming, it's only going to get worse."

The same holds true in light of man-made detention ponds and the increase in development in the region. And that's because when it rains, water is supposed to be absorbed into the ground, becoming groundwater, and diverted into streams, brooks and rivers.

Paved roads, however, divert water into a single pipe, blocking absorption and sending it directly to rivers and often causing floods.

Plus, a bulk of flood data that was gathered in the 1950s and 1960s and the building design plans arranged around it are no longer applicable, said Christine Tabak, executive director of the Merrimack River Watershed Council.

In years past, a detention pond created in a residential neighborhood may have been enough to handle water overflow from a 100-year storm. Today, due to climate change and other factors, those designs are outdated and ineffective, Tabak said.

Blame the beavers?

Beavers exacerbate the problem — but not for the reasons you may think.

"Love them or hate them, they are an important part of the ecosystem," Lilly said of these industrious critters.

Lilly said many people blame beavers for flooding on Route 114 in Lawrence, across from the North Andover Plaza.

And yet, Lilly said, the last two washouts there were caused by people removing a beaver dam upstream in Den Rock Park: When that dam was removed, the massive discharge of water overwhelmed the small beaver dam next to the roadway.

"Beavers have been trying to rebuild the dam, but people keep ripping it out. If the beavers had been left alone, the large beaver pond would have held a huge amount of storm water, slowing the flow to the culvert under Route 114. And while it wouldn't have prevented the flooding, it would have slowed it down," Lilly said.

Bottom line? If left alone, beavers help people manage storm water.

"We cause more problems when we interfere with them," Lilly said.

Rauseo said government re-introduced beavers in the state in the last 20 years. "For a long time, there were no beavers in Eastern Massachusetts," he said.

Rauseo, however, disputes part of Lilly's claim, saying that beaver dams can contribute to flooding.

"Any place you have standing water is a place you don't have flood storage," Rauseo said.

Looking for Band-Aids

Lenny Degnan, Lawrence Mayor William Lantigua's chief of staff, has owned an insurance company for 20 years. Since he has been selling insurance, he said, the type of flooding that occurred last week has occurred "10 times."

Flood waters soaked a neighborhood in Lawrence's Hampshire Street area, leaving apartments on Myrtle, Willow and Spruce streets underwater for days. The Spicket River runs through there.

Degnan noted that in the year 2000, the city obtained federal grant money to buy and demolish some two dozen homes on nearby Erving Avenue because of the constant flooding problems.

The Lawrence homes that flooded last week were the same buildings that were left submerged after the floods of 2006 and 2007. Officials wonder if removing some homes from the flood zone may be the answer again.

"It's something the city may have to look at ... We may have to look at getting a grant and tearing some of the homes down," Degnan said.

Lilly agrees.

"How many times will we allow flood-damaged houses and businesses to be rebuilt with federally backed flood insurance and FEMA assistance?" Lilly questioned. "At some point, you need to do the math and see that removing some buildings and returning that land to a natural state is both more cost effective and will help mitigate some of the flooding."

Lilly said the Lawrence project provided the new Kennedy Park next to Central Catholic on Marion Avenue. And while he had some issues with how the project was handled, he does think overall it's a solution worth looking at elsewhere.

"If we could do something like that on the opposite bank, between Myrtle Street and the river, it would alleviate a lot of other problems," he said.

Oscar Guiterrez bought his house at 162 Myrtle St. some 26 years ago. The house flooded at least eight times since. Guiterrez likes his home, which has three apartments, and never wanted to sell in the past.

Then last week, his tenants were evacuated and went to stay with family. He stuck it out at home using a generator for electricity. Now he says if the city receives grant money again to purchase and destroy homes, it won't take him long to make a decision.

"I'll sell it," he said.

Southern New Hampshire residents are still cleaning up after floodwaters ravaged their communities, leaving inches of water in some homes, particularly in Salem, and closing roads and schools.

At the Salem Animal Rescue League off South Broadway, there was still a couple of inches of water on the property Thursday, spokeswoman Valorie Hayes said.

"Something like this really throws us over the edge," she said.

During the storm, about 50 cats and 20 dogs had to be moved from their kennels to another building because of the floodwater, she said.

Residents of streets near the Spicket River found their homes flooded again, something that has happened several times in the last decade.

For the Brazil family of Spencer Avenue, it was the sixth time in the 17 years they have lived in their home that they had to deal with flooding.

The problem in their neighborhood has been so bad, the town is in line to receive a $1.9 million FEMA grant to buy nine nearby homes plagued by flooding. But the Brazils wonder why their house wasn't one them.

"We can't understand why we weren't part of that," said Laurianne Brazil, who lives at 5 Spencer Ave. with her husband, Thomas, and their two children.

Although surrounding communities did not receive as much damage, there were still flooding and closed roads from Derry to Danville.

On Thursday, Gov John Lynch asked FEMA to conduct its preliminary damage assessment so New Hampshire could receive federal disaster relief.

What can be done?

Finegold, the state representative from Andover, said he wants to meet with Andover Town Manager Reginald "Buzz" Stapczynski, staff from the state Department of Environmental Protection and local residents on the topic of preventing future floods.

"Taking on Mother Nature is incredibly hard and there may not be a solution, but I think we need to try to exhaust all possibilities," he said. "I've lived in the town for 30-plus years, and I've never seen Shawsheen Plaza flooded the way it has been flooded."

Finegold said he also wants to assemble a group to see if it makes sense to require people selling homes to disclose whether the home's basement has a history of flooding.

"I'd like to have experts in the area get together and discuss this," he said.

Police closed off part of Route 28 in Andover last week when the Shawsheen River overflowed. Bob Gilbert, owner of Andover Liquors in Shawsheen Plaza, said water covered 85 percent of the plaza's massive parking lot.

His store remained open, but he had almost no business for three days because people assumed the entire plaza was inaccessible, he said.

"As if the tax increase or the new tax on alcohol sales wasn't enough," he said

Rauseo offered tips for things that people can do at their own homes to help in a small way.

For instance, he said, people should not dump yard debris or litter in wetlands.

"You're just filling up places that need to be clear to hold water," he explained.

People can build rain gardens in their yards and use more permeable surfaces for driveways, too, Rauseo said.

Gilbert, the package store owner, is staying prepared.

"We now have resolved to keep our sand bags on a pallet out back so we don't have to call in for an emergency delivery of sand bags next time this happens," he said.

Lilly said learning acceptance, and being prepared, is a big part of the solution.

"These storm events are going to become more common and moderate storms are going to drop more precipitation than we now expect," Lilly said. "This trend started 40 years ago and it's not going to stop. We need to take steps to minimize the damage and mitigate our losses."

Among his suggestions?

Limit development in flood-prone areas, build better stormwater management structures to improve drainage, and take care of Mother Earth.

"The larger picture is that we need to re-examine our relationship with our environment," Lilly said. "Instead of looking at it as something to control and remake for our needs, we have to start working within the limits of sustainability and recognize that natural systems work well if we leave them alone."

Staff writer Doug Ireland contributed to this report.