GALLOWAY TOWNSHIP — Nine yellow, blue and green lines wave up and down on a small coordinate grid, plot points that retell a night last September when more than a foot of water overwhelmed Longport’s roads.
Almost everyone living on an island can share stories about moving their car or canceling plans when high tide or incessant rainfall, full moon or high tide hits.
But Dr. Stewart Farrell and his fellow Stockton researchers are using sensors to pinpoint exactly where flooding occurs most frequently, how long and how severely along selected streets.
Inside the Coastal Research Center nestled between two wildlife areas in Port Republic, the four-person team is using $300 Hobo sensors to track rain events in seven coastal communities: Longport, Avalon, Brigantine, Stone Harbor, Beach Haven, Long Beach Township and Long Beach Boulevard in Ocean County.
“This is going to provide the city with a document that says here’s when it happened and here’s the level of threat that it really is,” said Farrell, director of the CRC. “Instead of using these anecdotes like ‘Well it flooded terrible.’”
The project began August 2017 with Longport and Avalon, inspired by Winter Storm Jonas the year prior. In Ocean City, the third highest crest in recorded history was seen, putting the tide gauge in major flood stage. Dozens of cars in the region were damaged, as well as homes and stores.
Soon after, the New Jersey Coastal Coalition — a group of 20 coastal municipalities in Cape May and Atlantic counties — had an idea: document flooding on a more minute level, beyond photos and stories.
That’s when Stockton stepped in.
The cigar-sized sensors, made to record air pressure inside wells, were repurposed. Aided by public works departments, the researchers installed the gadgets on the underside of 24 storm grates throughout Avalon and Longport. A GPS unit is placed on top of each sensor to track its elevation.
How long each rain event lasts, the frequency and the water’s depth is recorded by the sensors in 15-minute ntervals. There’s a port on each one, and every three months, the drains are opened for researchers to upload the data onto a laptop.
Since last August, the boroughs has seen 143 rain events combined. On Friday morning — when a flood alert was issued for all of South Jersey amid 15-25 mph winds — the sensors recorded nearly every drop of rain.
“There are a lot of events, which is why it’s called nuisance flooding,” Farrell said. “But every once in a while, the nuisance becomes more real.”
Projections by Rutgers University scientists indicate sea levels could rise by 10 feet in New Jersey by 2100 if carbon emissions remain high.
Much of the information gathered so far from the sensors back up with science what most already know — areas at lower elevations are hit hardest, typically the back bays.
The studies in Longport and Avalon won’t be complete until March, but Bruce Funk has predictions on what they will show. He rounds off the usual flooding hotspots: 31st to 35th on Ventnor Avenue, and portions of Winchester and Monmouth avenues.
“We have a lower flood elevation in the middle of the town,” said Funk, Longport’s floodplain administrator.
He expects to use Stockton’s statistics in two ways. First, he’ll be able to pinpoint exactly which homes will be impacted by storms of a certain magnitude and send out alerts to only those residents.
But perhaps more importantly, the borough can use it to help secure grant money for water pumps, dikes and drainage improvements. Charts and numbers detailing precise flooding patterns are hard to refute, and can help form a priority list for future projects.
“We’ll be able to show empirically where the problem is,” Funk said. “It’s the hard facts.”