Irene: New flood maps offer more detail
Last year’s disaster heightens public interest
CAPITAL REGION Residents of Montgomery County got a firsthand look last week at new flood hazard maps, which could require some homeowners to purchase flood insurance and elevate their structures.
The maps, currently in preliminary form, are more detailed than the county’s old maps, which date back to the 1980s, but they’ve also raised questions. For instance, the new maps contain more precise data about elevation that would require some in the village of Fonda to raise their homes 2 feet to keep them out of harm’s way. For some, that might not be realistic.
“It’s going to be difficult for people to raise their homes 2 feet,” said Doug Greene, senior planner for the Montgomery County Department of Economic Development and Planning.
He said that some residents are considering taking a home buyout — allowing the government to acquire their property for 75 percent of its fair market value prior to the flood. The new maps, he said, “are a huge step in knowing what they’re up against.”
Greene said that even though the maps haven’t been officially adopted, the state recommends that residents use them “because they’re much more accurate.”
Counties throughout the Capital Region are updating their flood plain maps as part of a national effort to provide better information to homeowners, businesses and municipalities about the risks posed by flooding. Under the new maps, which were developed using sophisticated technology, as well as data about recent floods, some homeowners could find themselves outside of the 100-year flood plain, while others might find themselves inside it.
Interest in the new maps is heightened as a result of the disasters that took place almost six months ago — flooding that was much larger than a 100-year event.
“Clearly, municipalities and counties would like to get better mapping data,” said Bill Nechamen, chief of the Floodplain Management Section at the New York State Department of Environmental Conservation. “The new maps are easier to use.”
But they’re also a bit of a mixed bag, because some homeowners will inevitably learn that they’re required to carry flood insurance, which can be expensive.
“We recognize that there are local concerns, and we try to work with people to help them understand the process as much as possible,” Nechamen said. “Certain communities push back when they see the expanded flood plain.”
The Federal Emergency Management Agency launched its map modernization project in 2003, with the goal of creating digital flood hazard maps. Previously, the maps existed only on paper and were 20 to 30 years old.
The new maps, which are also known as flood insurance maps, are used to identify where flood insurance is required and help developers figure out where to build and not build. They focus on what is commonly called the 100-year flood zone, though planners and other experts tend to avoid that terminology because it gives people the idea that a big flood will only occur once every 100 years.
In reality, a flood has a small chance of occurring every year: Within a 100-year floodplain, the likelihood of flooding each year is pegged at 1 percent, while within a 500-year flood zone, the likelihood of flooding each year is pegged at 0.2 percent. What this means is that over the course of 30 years — the life of a mortgage, essentially — a flood has a 26 percent chance of occurring within a 100-year floodplain.
Congress initially provided FEMA with $1 billion for the five-year project, which resulted in new maps for 92 percent of the country. New York received $200 million in that initial round of funding and focused on mapping the state’s more populated areas, according to Nechamen.
After major flooding in 2006, Schenectady, Herkimer, Oneida and Montgomery counties also received funding to update their maps. The severity of the 1996 flooding sparked interest in the Mohawk River and its potential to cause extensive damage in nearby communities.
“The floods were greater than anticipated,” Nechamen said. He said the Mohawk River is complicated because it contains numerous dams and a canal system.
Schenectady County’s new flood plain map is currently in the appeal process. Joe McQueen, a spokesman for the county, said the county is waiting for DEC and FEMA to revise the map and send it back to them for further review.
About half the state’s land area, covering about 90 percent of the population, has been mapped thus far, but nearly two million people live in areas that have not been mapped. One area that hasn’t been mapped is Saratoga County. Nechamen said that a mapping project is expected to begin there sometime next year.
“Saratoga County is a high priority because of its rapid development,” he said.
No crystal ball
John Garver, a Union College professor of geology who has studied flooding on the Mohawk River, said that the new maps are helpful but also have limitations. Because they were created using information about past floods, they do not take into account whether flooding is on the rise.
“We can only base future projections on past records as long as things are linear and non-changing,” he said. “But what if things are changing?”
Garver believes that flooding is on the rise in the Mohawk River watershed. He said that the main culprit is the Schoharie Creek, which is discharging water into the Mohawk River at a much higher rate than in the past as a result of an increase in storms such as hurricanes and nor’easters.
“The Catskills are seeing more precipitation,” he said.
Another issue is that flooding in the Mohawk is exacerbated by jams caused by ice and debris — a factor that the new maps do not take into account, Garver said. “The maps under-represent the very high water that can occur in the Mohawk,” he said. “Anyone who lives in the Stockade knows that whenever there are ice jams, it floods. … The modeling for the flood plain maps assumes free-flow conditions and no jams.”
Despite the limitations, Garver said that homeowners should pay attention to the data and learn more about the implications for their property.
Ed August learned about the limitations of the updated maps during the devastating flood caused by Tropical Storm Irene last summer.
Up until 2009, August had flood insurance on his home in the village of Schoharie. But then his insurance company sent him a letter informing him that he was no longer in the 100-year flood plain, and he canceled his policy. This decision came back to haunt him, he said, when his home was heavily damaged by flooding.
Schoharie County’s new flood maps went into effect in 2004. The county was actually a pilot site for modernized mapping, and efforts to update maps there began in 1999. Nechamen said Schoharie County was selected as a pilot site because of massive flooding that occurred there in 1996.
“We found that in Irene and Lee, the maps were pretty accurate,” said Schoharie County Senior Planner Shane Nickle. Even so, “We never dreamed that we’d see 5 to 6 feet of water in the 500-year zone.”
More recently, the county received additional funding to develop more detailed maps of a handful of communities near West Creek or Cobleskill Creek, including Richmondville, Cobleskill and Seward. Those maps are just now being adopted, according to Nickle. In some places, especially along West Creek, the flood plain has shrunk, while in others it has expanded, he said.
Nickle said Schoharie County was interested in obtaining more detailed maps of the Richmondville-to-Cobleskill corridor because that area is experiencing development pressure.
Anyone can purchase flood insurance, even those who are not located in that 100-year zone.
Garver organizes the annual Mohawk Watershed Symposium, which focuses on issues related to the Mohawk River watershed, including flooding. This year’s symposium will be held on March 16 at Union College.
In New York, the state Department of Environmental Conservation and FEMA coordinate the floodplain mapping program.
Preliminary flood hazard maps for counties throughout New York can be viewed at www.rampp-team.com/ny.htm.