Experts Say Expect More Rain and Flooding

By DAVID SMITH/ecoRI News contributor

WOOD RIVER JUNCTION, R.I. — The shoreline is retreating and it won’t take a big storm or hurricane to severely damage structures along the coast, according to David Vallee, the hydrologist-in-charge at the Northeast River Forecast Center of the National Oceanic and Atmospheric Administration (NOAA).

Vallee was one of two speakers at a recent Wood-Pawcatuck Watershed Association discussion entitled “Adapting the Watershed” and held at Chariho Middle School.

He noted that 2012 Superstorm Sandy devastated the Rhode Island coast, leveling dunes and destroying property, and the October storm wasn’t even a Category 3 or 4 hurricane. It was “just” a severe storm with a “massive wave field” and 4.5-foot storm surge, he said.

Vallee has gathered data that shows that the intensity of rainfall has increased during the past 30 years, and that there are fewer droughts. That has held to higher water levels in rivers, and combined with urbanization of the floodplains, has increased the frequency and severity of flooding.

For example, Vallee noted that the Scituate Reservoir was designed in the 1920s to be filled by June 1. The reservoir now fills around March 1, he said, and the excess flows into the North Branch Pawtuxet River.

The common theme during the past decade has been slow-moving weather systems with multiple events in succession before a major storm. Each of these type storms is being fed by a tropical connection, Vallee said.

Global warming is changing the jet stream, he said. He said the Northeast is losing its east-to-west flow of weather systems, and there is now more north-to-south flows. Rhode Island also is seeing a temperature increase of about 1 degree every 50 years, according to data collected at T.F. Green Airport.

Vallee said summers in Rhode Island are getting hotter, more akin to the weather in New Jersey.

And as expected, water levels are changing.

“All three (gauge) locations on the Pawcatuck River ... indicate an increase in flooding,” Vallee said. “Wood River Junction is the smallest of the bunch but all three locations are showing an increase based on our examining the number of floods over the period of record, which dates to between 1929 and 1940 or so.

“The reason the basin isn’t seeing the rate of increase as some others, we hypothesize, may have to do with the amount of natural storage and still undeveloped land allowing for the basin to handle additional rains and wetter conditions, but the Wood River and the Pawcatuck at Westerly have experienced a more substantial increase.”

In years to come, Vallee said there will be many businesses and homes along the Pawcatuck River affected by the rise in sea level and related flooding.

“Adapt or retreat,” he said, noting that in time there will not be a choice. He said Atlantic Avenue in Misquamicut will not survive.

“Atlantic Avenue is tremendously vulnerable because of sea-level rise and the fact that a Category 3 hurricane will be capable of producing surge in the range of 8 to 12 feet above that increase in sea level,” Vallee said. “Sandy produced a 4- to 4.5-foot surge, one-half to one-third of what this region will see again. Most of the houses lack protection to withstand such a strike.

“Some places don’t belong there any more. But it gets back to the property tax base. What do you do? How do you convince people to leave? It’s only a matter of time before the big hurricanes come through.”

He cited one example of development adapting to a changing climate: the redevelopment of the former Royal Mill Complex in Warwick on the Pawtuxet River. In that case the bottom two floors were used for parking. That allows the flow of water underneath the structure instead of putting living space in danger of being flooded.

Keeping lookout
Vallee’s job is to develop forecasts and issue flood warnings at least five days in advance. His job is made easier by the river gauges maintained by the U.S. Geological Survey.

The other speaker was Michelle Burnett, a state floodplain coordinator with the Rhode Island Emergency Management Agency. She spoke about flood insurance, storm preparations and planning, and her agency’s role in handling federal grants in the aftermath of disasters.

The R.I. Emergency Management Agency is currently updating state evacuation plans. The agency has oversight on more than 600 dams, and held its annual hurricane and preparedness conference June 20 at the Crowne Plaza in Warwick. Hurricane season began June 1.

One of the biggest components of her agency is mitigation, such as in the case of coastal development, urging people to build better and smarter. One of those ways is to elevate coastal homes on pilings at least 15 feet high, with breakaway walls at ground level to allow water to flow underneath.

She said several homes in Misquamicut are now being raised in this manner. The problem, she said, is that if not all the homes are raised, one could get washed off its foundation and damage other structures.

Burnett also noted that Rhode Island has suffered an unprecedented four federal disaster declarations in four straight years, beginning with the flooding in March 2010, tropical storm Irene in 2011, Superstorm Sandy in 2012 and a severe winter storm in 2013.

Burnett said climate change permeates everything her agency is doing. “It will exacerbate all of the planning, because it effects storms, hurricanes and flooding,” she said.

Her message to the audience was to be prepared for the next emergency, whether that be by buying flood insurance, creating a storm kit that includes food, medicine and water, or just making a plan regarding what you will do if you have to evacuate or get separated from loved ones.