Sunday, April 11, 2010

Rhode Island flood a perfect storm of several factors

C. Eugene Emery Jr. in the Providence Journal: On one level, you could blame The Great Flood of 2010 on an extraordinary storm, a weather system that, over two days, dumped 8.8 inches of rain in Warwick and, in some areas of Rhode Island, even more. But that’s only part of the story.

The calendar, human development and even the height of the Scituate Reservoir, the source of much of the state’s drinking water, all played a role in making the flooding so disastrous to people throughout the region, particularly along the Pawtuxet and Pawcatuck rivers, said David Vallee, a hydrologist, West Warwick native, and chief of the National Weather Service’s Northeast River Forecast Center.

Vallee, who led the team that was trying to forecast the rise of the rivers and advise state officials about the risk of flooding, said that if there had been more greenery to soak up the rain or if rains had not topped off the reservoir weeks earlier, the scope of the flooding might have been reduced. Extensive development along the Pawtuxet might have played a role as well but a state planner said it may not be as large as some would think. Whatever the combination, it walloped the state.

…One source of the destruction was all the wet weather the state received weeks earlier… A second factor was the season. Rainstorms that occur early in the spring and late in the fall are quick to swell streams and rivers because there’s no vegetation to hold and soak up the precipitation.

…Perhaps just as important as the acts of God were the acts of man. Every time someone builds a home, erects a business or paves a parking lot, it eliminates a piece of terrain that would normally absorb and hold the rain, and there’s no debate that there’s been a lot of development along the Pawtuxet and its tributaries over the last half century, such as the stores on Route 2 and the two major malls.

…If a city or town tried to restrict floodplain development, it would raise an issue of property rights and the question of whether it would be denying someone the use of their land, said Mark Carruolo, planning director in Warwick. “It would constitute a ‘taking’ of the property.”

Ultimately, Vallee said, the best predictor of where the floodwaters would go turned out to be lines on the FEMA flood maps that designated the 500-year floodplain. Most of those areas ended up with water. “I hope this is not the new climate change,” Vallee joked….

Out of date, I know, but NOAA had this picture of Hurricane Carol's storm surge hitting the Edgewood Yacht Club in 1954, in Rhode Island

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