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Climate Change + Urbanization = More Flooding for Montgomery

By Rebecca Koblin | November 8, 2021

Whether Hurricane Ida will be classified as a 100-year-flood is still up for debate.

However, one thing is for sure. “During 100 years of record keeping along the Millstone River … Floyd, Irene, and now Ida, are by far the three largest events on the Millstone River in the past century,” New Jersey State Climatologist and distinguished Rutgers Professor David Robinson told The Montgomery News.

Cars submerged in high waters at Rocky Hill Bridge over the Millstone River.

“Six of the eight largest floods on the Millstone River, over the last 100 years, have occurred in the last 20 years,” Robinson said.

New Jersey residents are seeing more frequent “heavy” rainstorms. Robinson theorizes that a warmer atmosphere means that moisture can be held in the rain clouds.

“The oceans are warmer, so it is easier to get the moisture off the oceans and into the atmosphere,” he said. “It stands to reason that when a storm comes along, like Ida, it will produce more rain.”

Our climate on steroids

Robinson describes climate change as “the climate system on steroids.” He explained that rare and unusual storms are not caused by climate change, but rather that “climate change, in the case of an Ida, has an amplifying effect. It may have made the storm that much wetter… You don’t know what would have happened without the steroids. Something would have happened, but you don’t know if it would have happened as often or at as high of a magnitude,” Robinson said.

Flooding as a way for life for Montgomery residents

Rutgers Civil and Environmental Engineering Professor and Montgomery resident Qizhong (George) Guo says climate change is “not the only reason we had such severe flooding throughout Montgomery.”

“Right now, at this point… water level increase has more to do with urbanization [in Montgomery] in the last 50 to 100 years,” than with climate change said Guo.

According to Changing Landscapes in the Garden State: Land Use Change in NJ 1986 through 2015, “New Jersey has a long history as having the highest population density, as well as having the highest percentage of its land area in urban land uses of any state in the United States.

“By the year 2015, nearly 33 percent of the state’s nearly 5 million-acre territory (excluding marine waters) had become urbanized.”

In the mid-1980s, New Jersey’s stormwater management systems were designed for water quantity only, as a way to control basic runoff.

“If a house was built after the mid 1980s you will see a detention basin there,” said Guo. “Homes built before the mid-1980s had little to no water redistribution and runoff rules. Because of this, developments weren’t required to create a way to absorb and collect runoff to the same standard that we have today.

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Population growth and rapid urbanization have caused rainwater runoff to became a problem.

“When we convert land that would be covered in dirt, grass, and trees into land covered by concrete foundations and asphalt driveways, we take away a large amount of space that once would have absorbed and held rainwater,” he said. “Today developers are required to account for this, but any development created before 1984 did not have to follow such strict rules and regulations.”

Ultimately, Montgomery Township needs to create incentives for people to update any homes that were built before the 1984 stormwater regulations, said Guo. Collecting storm water Rain gardens, according to the United States Environmental Protection Agency, are a great way to collect “rainwater from a roof, driveway, or street” and allow the water to be soaked into the ground. “Planted with grasses and flowering perennials, rain gardens can be a cost-effective and beautiful way to reduce runoff from your property,” according to Guo.

Porous concrete is another sustainable option for rainwater absorption. Montgomery Township has a few feet of porous concrete on the new pathway on Skillman Road, near Saint Charles Borromeo Church. “We recently completed our Skillman Park pathway project, which included a (very small section of) porous concrete, said Montgomery Township Engineer Gail Smith. It’s a pilot project, she said, noting that stormwater flows through the concrete into the ground. The project was created through a partnership with the Rutgers University Center for Advanced Infrastructure and Transportation and the New Jersey Department of Transportation and Federal Highway Administration.

Smith said, “with the latest state requirements, we upgraded our stormwater ordinance to be compliant and go above and beyond to adopt the green infrastructure requirements where more environmentally friendly methods are used to manage the stormwater.” The issue for our community now is finding solutions to older developments increasing rainwater runoff into our streams and rivers.

Help for those who live on what has now become a floodplain

There are options for people who currently live in floodways and whose properties have been damaged by storms or storm-related flooding.

According to the State of New Jersey Department of Environmental Protection, “The Green Acres, Farmland, Blue Acres, and Historic Preservation Bond Act of 2007 authorized $12 million for acquisition of lands in the floodways of the Delaware River, Passaic River or Raritan River, and their respective tributaries, for recreation and conservation purposes.”

The Blue Acres program allows homeowners to sell storm damage-prone properties to the state so that the land can be restored to its natural condition. By restoring the natural floodplains of an area the state not only moves residents out of harm’s way but also helps to mitigate flooding.

“Climate change is raising the playing field if you will. Everything is affected,” says Robinson. “Today’s temperatures are affected by climate change. A snowstorm can be affected by climate change and Ida, likely, was affected by climate change.”

“Now, what we need to do is concentrate on how we can better alleviate storm conditions through sustainable means, because, more than likely, the next Ida will not be far behind.” ■


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