Fluctuating temperatures are causing massive river ice jams | Popular Science
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Fluctuating temperatures are causing massive river ice jams

These ice chunks are fascinating to look at, but can cause serious flooding.

Mohawk River Ice Jam

Mohawk River ice jam

A railroad bridge across the river causes ice chunks to jam behind solid surface ice.

Stan Horaczek

Right now, a section of the Mohawk River in Schenectady, New York, is doing its best impression of a giant snow cone. Enormous chunks of ice, some weighing thousands of pounds, have crawled up onto the shore and covered the surface of the water just down the road from the original GE plant. The phenomenon is called an ice jam, and while it’s fascinating to look at, it can cause serious floods in surrounding areas.

This winter has proven especially conducive to ice jamming, due in large part to the wild temperature swings we have endured. Here’s what’s happening.

Ice Jam

Mohawk River ice jam

Giant chunks of ice washed up on the shore of the Mohawk River.

Stan Horaczek

This type of jam is called a breakup jam. “Rain and snowmelt cause the water level to rise and break its connection to the bank,” says Steven Daly, a research hydraulic engineer with the US Army Corps of Engineers at the Cold Regions Research and Engineering Lab in Hanover, New Hampshire. “It breaks up the ice and the water starts moving the pieces until they reach a point where the capacity of the river can’t carry all the ice.”

This typically happens when the temperatures get cold enough to form a thick layer of ice on top of the water, then warm up rapidly, which is exactly the situation the Mohawk River has been in this year. The average temperature during the first week of January stayed well below freezing, with a high that remained below zero on several days. Then, by the 13th of January, it was 60 degrees with rain, which is a perfect recipe for a pile-up like this.

Mohawk River Ice Jam

Frozen river ice

Frozen river ice melts in layers as chunks wash up on shore.

Stan Horaczek

“The Mohawk River is famous for ice jams,” Daly says. “Long, cold winters make thick ice to cover the river. If it warms up gradually, you won’t get an ice jam. It’s rapid rise and flow that causes it.”

The Army Corps of Engineers keeps an Ice Jam Database, which has already tracked more than 100 jams in 2018. New York is in the lead with 25 ice instances so far, but other states—many of which are in the northeast part of the country—are already approaching double digits.

Mohawk River ice jam

Mohawk River ice jam

Jams can cause floods, which threaten buildings near the banks.

Stan Horaczek

These icy traffic jams tend to happen in the same places each year because of the structures of the rivers. “Any structure that crosses the channel, like a dam, lock, log boom, or even a bridge with a lot of piers, or a sharp turn in the river can cause a jam,” says Daly.

In the case of the Mohawk, it’s this railroad bridge near the old Schenectady train station that impedes the flow. Beyond the bridge, the water is frozen, but smooth.

Mohawk River Ice Jam

Mohawk River ice jam

The ice jam in this section of the river goes on stretches beyond the horizon.

Stan Horaczek

Breaking up is hard to do

Once a jam is in place, there’s not a whole lot anyone can really do about it. “We would never send a boat out into a jam like this,” says Daly. “The only thing you can do is try to pick up ice from the shore using equipment.”

It is, however, possible to get ahead of the problem. In 2004, a Department of Environmental Conservation project installed a jam-prevention system in a flood-prone section of the Cazenovia Creek, roughly two miles southwest of Buffalo. The system consists of nine steel-jacketed concrete piers, spaces 17 feet apart. They extend 10 feet out of the water and are five feet in diameter. In essence, they’re big cement pillars designed to control the flow of ice chunks down river to prevent them from piling up and causing floods.

While the project has helped the flooding problem, it didn’t come cheap. The DEP report puts the total cost of construction at $1,828,962.60. So, while these problems may persist in some areas, it takes considerable investment in infrastructure to solve the issue.

Mohawk River ice jam

Mohawk River ice

Thick slabs of surface ice are formed over long, cold months.

Stan Horaczek

More jams are coming

If temperatures continue to fluctuate, we can expect to see more of this phenomenon going forward. And while it’s very cool to look at, Daly says you certainly shouldn’t go walking on it. “It may look solid, but it’s not,” he says. “It’s impossible to get you out.”

Mohawk River Ice Jam

Mohawk River ice jam

Large chunks of ice climb onto the banks where the river bends.

Stan Horaczek

Mohawk River Ice Jam

Mohawk River ice jam

Some of the chunks are more than a foot thick.

Stan Horaczek

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