Indiana borough flooding I
By Cara Mehalek
INDIANA — Several short intense storms flooded streets and homes here in June and July. For affected residents, that’s not news. It’s been a dispiriting routine for decades.
But a new political reality has floated up in the wake of the summer floods. After hearing citizen complaints about chronic flooding and borough inaction, borough officials announced Oct. 3 that they will go door-to-door in flood-prone neighborhoods to gather data for municipal flood maps.
Meanwhile, additional data are coming from Indiana University of Pennsylvania geoscience professor Katherine L. “Katie” Farnsworth and her students, who have been measuring municipal surface water trends, too. One tentative conclusion Farnsworth draws from the data is that local flooding may have a link to global climate change.
The summer 2017 storms “produced what we consider very intense rainfall,” Farnsworth said in a Sept. 7 interview in her Walsh Hall office. “The last time we saw rainfalls of that intensity – that much rain, even – was in the late ’70s.”
On July 20, 1977, a storm that dumped nearly 12 inches of rain in 10 hours flooded Johnstown and parts of Indiana County.
For Indiana borough, 2017 was notable for three flood events in one month, Farnsworth said.
The first, in June, produced a “bank-full” flood, in which water reaches the top of the stream or river channel but doesn’t overflow, she said.
On June 22 and July 14, the second and third intense storms of the summer each amounted to “about a fifty-year precipitation event,” Farnsworth said.
The local flooding was not necessarily linked to global climate change, Farnsworth said. A bank-full flood every year or two is not unusual.
However, the intensity of the rain may be a climatic factor.
“We do know that as the climate is changing that we’re getting not necessarily a change in the total rainfall, but that we are getting more intense rainfall events,” Farnsworth said.
Average annual precipitation in Pennsylvania has increased by 5 to 10 percent in the past century, and precipitation from extremely heavy storms has increased by 70 percent in the Northeast since 1958, according to an August 2016 Environmental Protection Agency document.
The probability of flooding rises with global temperature, Farnsworth said. And the trends are not easy to keep up with.
“The federal government puts out flood maps that show what they estimate to be the hundred-year floodplain,” Farnsworth said. “However, those are done through modeling with older data, and our climate has changed since much of that was done. They say it’s a hundred-year, but it’s probably less than that now.”
THE FEDERAL DATA raise questions about the future of local flooding. But the borough’s problems date back to the borough’s roots more than 200 years ago.
Buildings were constructed in the Marsh Run floodplain before regulations were developed, according to Section 207 of the 1978 Flood Plain Management Act and the Federal Emergency Management Agency’s national flood hazard map.
“There’s no floodplain without construction on it in a good portion of Marsh Run,” Farnsworth said.
The stream enters the borough just south of Indiana High School and exits next to the Kovalchick Convention and Athletic Complex, where it meets Stoney Run. In between, part of Marsh Run flows underground between the 400 block of Washington Street and the 300 block of Burns Avenue.
Some homes and businesses are built right on top of the floodway – for example, the Sheetz store at Philadelphia and Fourth streets.
JILLIAN P. MATHEWS, 23, a senior majoring in biology and geoscience at IUP, spends a few hours every other Thursday afternoon collecting data on Marsh Run under the guidance of Farnsworth and with the help of fellow undergraduate geoscience senior Manuel “Manny” A. Torregrosa, 38.
Mathews, a petite, vocal New Jerseyite, and Torregrosa, a tattooed Puerto Rican veteran, gather data-collection equipment, suit up in tall rubber boots and clamber down into the stream at four locations:
- North Second Street beside Colonial Collision Center,
- residences on North Fourth Street,
- residences on South Sixth Street,
- and near the Wayne Avenue side of the KCAC and the Hilton Garden Inn.
“For my senior project, I’m tracking the discharge, and the water-level changes,” Mathews said while assembling a flow tracker near the KCAC on Sept. 21. “Then we’re also looking at precipitation rates.”
Each of the four locations is shaded by trees, some of which still are draped with flood debris several feet above the normal water level. On a normal day without rain, the creek water is inches deep and almost still.
The first data logger, the farthest downstream, is near the KCAC and the adjacent hotel.
During the June 22 and July 14 floods, the water level in what is normally a gentle, shallow stream would have been flowing well over her head, Mathews said.
Torregrosa notes a cinder block that has been lifted several feet by the flood from the bed of the channel to its bank.
“Wayne Avenue was flooded, so the water was about two meters high,” Mathews said. “There’s debris all the way into the top of these trees. We would’ve been completely underwater.”
At Colonial Collision Center on North Second Street, farthest upstream, Marsh Run typically floods after 15 minutes of intense rainfall. It takes an additional 15 minutes to flood at the KCAC location, according to Mathews’ research this year.
“When the water comes here, it’s kind of like that scene from the ‘Lord of the Rings,’ when they’re crossing that bridge on horses and shit,” Torregrosa said. “That’s pretty much how it is. It can rain someplace over there, and it doesn’t slowly come up here. It’s just a huge wave.”
FARNSWORTH SAID she hopes the research that she and her students are conducting can contribute to a solution to the borough’s flooding problem by collaboration with local officials on an important question: Is there a way to reduce flooding by slowing the amount of water flowing directly and indirectly into Marsh Run during intense storm events?
“Our project that we’re doing is separate from the borough and the township, but we talk with them and share our information with them,” Farnsworth said. “The borough hasn’t paid us to do any of this. We’re just doing it because it’s an interesting scientific applied question.”
Cara Mehalek, a senior majoring in journalism and geoscience at Indiana University of Pennsylvania, is from Belle Vernon.