Water does what comes naturally

| 15 Feb 2012 | 10:33

Experts at flood forum say controlled development and stream gauges can help manage a tough problem Washingtonville — A forum to help residents make sense of the area's ever-worsening floods offered many explanations but few easy solutions. Rivers are always changing, the experts said. And this makes long-term planning difficult, especially when it comes to development. “Running water contributes more to shaping landforms than all other causes combined," said Major Margaret McGunegle, a geography instructor at West Point, at the Orange County Water Authority-sponsored "Flooding 101." Rivers create the broad floodplains where people like to live. They are easy to build on and close to sources of water. And all is well — until a big storm turns the plain back into river. Geologist Adam Kalkstein, also of West Point, said the effects of Hurricane Irene and Tropical Storm Lee were made worse by ground already saturated from the more than 15 inches of rain that fell in August. Our topsoil is thin, he said, with not much room to absorb water. And our mountainous topography plays a role: water from higher elevations runs down fast and straight. Once it reaches the flats of the floodplain, it slows down and starts to wind back and forth through the valleys. This causes cycles of erosion and sediment deposits. The water moves faster on outside curves. On the inside curves, sediment builds up, creating sandbars and higher banks. Flood scars show where the river has been. “Look at Google Earth," said McGunegle. "Where the river has been, it will be again." State obligated to work with towns The New York State Department of Environmental Conservation (DEC) has a mandate to make sure towns manage their floodplains so that they can participate in the National Flood Insurance Program, said William Nechamen, the head of floodplain management at the DEC. Floods are a natural process accelerated by development, he said. Paved surfaces prevent water from soaking into the ground, which increases runoff and makes flooding worse. If towns fail to insure that new development is built to flood standards, he said, individual homeowners will wind up paying more for flood insurance. But he noted that the conservation department only regulates and does not enforce the regulations. He said regulatory floodways should not be developed at all. Streams must connect with their floodplains, and areas with the greatest velocity of runoff must be kept clear. According to current building regulations, the lowest enclosed area of a house must be above the 100-year base flood elevation, plus two feet for residential structures (see related story). It is up to local towns to pass ordinances that reduce the flood risk in new development, he said. Banks will require flood insurance for any structure built in a designated Flood Hazard Area. Unfortunately, said Nechaman, some homeowners have erroneously been told they cannot get insurance. But it is available to homeowners who live in municipalities that participate in the Flood Insurance Program. A countywide Flood Insurance Rate Map was adopted in August 2009. Parts of the map have been updated, but some areas are still based on data that is 10 or 20 years old. Cost is the determining factor: stream studies cost $15,000 per stream mile. Stream gauges are one means of getting data on waterways, Nechaman said. But Orange County has only two U.S. Geological Survey water gauges that constantly collect data in real time. It costs about $30,000 to install them and $15,000 a year to maintain them. The money previously earmarked for the gauges is no longer available. In the past, money for stream gauges and studies by the Army Corps of Engineers was available to localities through Congressional earmarks, which allow lawmakers to direct federal funds to projects in their districts. But in the past year, Congressional leaders, including U.S. Rep. Nan Hayworth, declared a moratorium on earmarks to bring down spending. The Orange County Water Authority has managed to install six less costly gauges at a cost of about $1,000 each. Data is gathered continuously but not uploaded. The staff collects it onsite once a month. Brian Drumm, a DEC biologist who works with stream and wetland permit applications, said homeowners and municipalities are allowed to clear streams of woody debris, like branches and fallen trees. But a permit is usually needed for dredging, in which accumulated sediment is excavated and the stream bed deepened. In some cases, he said, dredging will make stream banks less stable. He said DEC representatives will inspect streams where work is proposed and make decisions on a case-by-case basis. Leonard DeBuck, a nursery sod farmer from Pine Island, said his inventory was wiped out by the recent floods. He now has to buy sod from other farmers to supply his clients. He and others in the audience wanted to know: Why can’t we get the government to come up with new ways of dealing with floods? “Where is government responsibility to maintain the capacity of waterways?” DeBuck asked. “Should we farm the floodplain or fold our tents?” He said keeping waterways clear was common sense, like taking hair out of bathtub drain to let the water flow freely. “Where does the responsibility lie?” DeBuck asked. “When will the DEC or someone else respond?” Another audience member talked about the increased probability of flooding near dams, and asked if it were possible to reduce the height of the dams in her area by one foot a year. Still another asked if there were any studies comparing the cost of flood-prevention measures to the cost of restoration. The experts could not answer these questions. And there are even tougher questions to come. This well-attended forum, the first in a series, emphasized waterways and their behavior. The next few sessions will be devoted to solutions. The questions promise to be more plentiful, and harder to answer. The Orange County Water Authority is sponsoring the series in partnership with the Town of Blooming Grove, Orange County, and the Moodna Creek Watershed Intermunicipal Council. The next session is planned for Jan. 17. The place and time have yet to be determined. What 100-year flood really means The term “100-year flood” is not quite accurate, and not so rare. If you live in a 100-year flood area, you have a 1 percent chance of flooding over one year and a 26 percent chance of flooding over 30 years. That’s a 1 in 4 chance of flooding if you remain in the same area for 30 years. To find floodplain maps, visit msc.fema.gov or call 1-877-FEMA MAP.