Why are flash floods now so frequent?

Jul 29, 2015 at 09:54 am by Observer-Review


Why are flash floods now so frequent? ADVERTISEMENT

Why are flash floods now so frequent?

FINGER LAKES--A recent weather pattern has caused the area to face far more flash flooding events than it normally must endure. Meteorologist David Nicosia with the National Weather Service (NWS) in Binghamton said since May of 2014, flash flood warnings have been issued 13 times in Yates County. He added there have been 25 actual flash flooding events in Yates during this timeframe, with 21 of them coming in 2014. Nicosia stated these are significant numbers, as the average tends to be three flash flooding events every four years in Yates County.
Nicosia said a flash flooding event is classified as any flooding that occurs less than six hours after rainfall, but added it often times hits within an hour.
"Sometimes the rains come and 20 minutes later it is flooding," Nicosia said. "That is how fast it is coming."
Nicosia mentioned the reason the area has seen more flooding events recently is because the soil is already saturated with so much water that when additional storms come through, the water has nowhere to go and causes flooding. He said it has been very wet in the Finger Lakes region in both the winter and the summer seasons, adding the water in the soil evaporates which can then fuel the storms.
"It is a self-perpetuating process," Nicosia said.
When it comes to issuing a flood warning, Nicosia noted the NWS has a program that keeps track of soil moisture, setting a rainfall threshold where they will issue a warning if their radar estimates meet or exceed that precipitation threshold. He said since the soil is so wet, the thresholds are low to the point where 1.5 to two inches of rain in an hour could trigger a warning. Nicosia added these types of rainfalls are not that uncommon in the region.
Nicosia said there is a particular weather pattern dating back to two winters ago where high pressure in the north Pacific forced the jet stream to buckle farther north. He said this causes storms to miss the Rocky Mountains, come down through Canada and hit the area more directly without losing as much of their energy. Nicosia mentioned this weather pattern will break at some point, but added if it does not before winter approaches, the area could be in for "another cold, nasty one."
While Nicosia noted there has not been much tropical storm activity, they could potentially cause more issues if one were to develop.
"We do not want any tropical storm activity," Nicosia said.
More than a month after flash floods hit the area, Yates County is still dealing with the effects. Yates County Emergency Management Director Brian Winslow said Yates County suffered approximately $1,270,766 in damages during the flash flooding that hit the area in mid-June. Winslow said the town of Middlesex appeared to be the hardest hit by the flooding, along with several state and county roads.
While Milo Town Supervisor Leslie Church said they do not have an official damage estimate yet, she noted there were two minor landslides along East Lake Road, along with a badly damaged bridge at Plum Point Road. Church said they are calling on the community to help clean out their watercourses (the pathway that water travels on a homeowner's property) so they do not get bottlenecked where things get stuck and cause more property damage. She said the bridge at Plum Point Road will need to be replaced, with work not expected to begin until October of this year.
"[The flood damage] has caused a concern," Church said. "We were lucky in the first flood last year to not have much damage, plus FEMA (Federal Emergency Management Agency) reimbursed us for our damages. This time that is not going to happen, and we will be incurring all those costs. The fact the tax cap could be lower is definitely cause for concern."
Middlesex Supervisor Robert Multer said his town estimates their damages at $300,000, adding the town is still dealing with damage to their roads.
"We had severe damage on South Lake Road and a couple of side roads," Multer said. "We lost most of a section of Wolfanger Road. They are still repairing the damage. It was still passable but it is a major repair to fix that."
Multer said the town inspects their culverts every year, adding they are cleaned out after every storm. He said they tour the roads yearly and if they see a culvert with an issue, they take care of it.
"The problem is with the storms we have been having, in the last two or three years we have had some major rain events," Multer said. "The town of Middlesex terrain is hilly with a lot of gullys and the water has a great force that brings down debris from the hill and it accumulates at the culvert. I don't know of any way to prevent that."
Multer said with estimates having the state tax cap lower than in previous years, the town will now have to delay certain work in order to take care of the damages suffered in the flood. He noted because it does not look like they will get any aid, the town will probably not be able to do any road surfacing this year.
"If you don't do that, it doesn't take long for the roads to deteriorate," Multer said.
Meanwhile in Schuyler County, Nicosia said flash flood warnings have been issued seven times since May of 2014, with four actual flooding events. He noted all of Schuyler's flood events occurred in 2015, while the average trend in Schuyler is one flash flood every other year.
Schuyler County Administrator Tim O'Hearn said Schuyler County Soil and Water has projected damages to be at just less than $5 million of public infrastructure. He added there is an equal amount on private land encompassing flood damage, stream stabilization needs, private roads and structures.
"The county is estimating its share of damage to be under $500,000 to roads, culverts and bridges," O'Hearn said. "The towns of Tyrone and Reading each suffered significantly more in losses."
With New York State expecting a lower tax cap for the upcoming budget season, the county expects flood repair expenses to cause even more difficulties for the coming year.
"None of these expenses were anticipated, obviously, and it may be necessary to use reserve funds or cut back on other scheduled projects for 2015," O'Hearn said. "This places additional strain on an already stressed highway budget and will make it even more difficult to maintain our infrastructure while staying within the tax cap in 2016."
Much of the damage was caused when the flood waters rushed in overwhelming culverts, clogging them with debris and causing the water to overflow. O'Hearn noted there is no longer a formal program for culvert inspection and maintenance, adding it was a casualty of budget reductions over the past decade. He said the county highway superintendent does an annual road condition inspection which includes culvert and bridge assessments, but mentioned it is largely a reactive program dealing with problem areas as they are detected.
"It is important to note that in the case of severe weather events we have recently experienced, no amount of prevention will completely eliminate the devastation from deluges of four to five inches of rain in one to two hours," O'Hearn said.
Along with the damage to area roads, the Finger Lakes Railway (FGLK) from Watkins Glen to Himrod Junction and the Norfolk Southern (NS) from Himrod Junction to Geneva also required repairs from flood damage. Finger Lakes Railway will spend $75,000 to replace four 12- and 24-inch culvert pipes with 24- and 30-inch pipes, plus another $125,000 to replace culvert headwalls and expand ditches in order to direct water away from the tracks, away from the neighbors, and down to these culverts that pass under the tracks. Work on the rail line has continued since the storms.
"Our Maintenance of Way Department employees do their best to ensure the integrity of the system's drainage facilities and are always vigilant when severe weather arises," said Jon Gadsby, manager of track for FGLK. "If a severe weather event occurs, we send patrols ahead of any train to visually inspect the line."

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