Scientist: Improve flood-plain maps – Conference focuses on mitigating sea-level rise
By Henry J. Evans Jr.
Wed, Dec 22, 2010 Call it what you might – global warming or climate change – there are few scientists or people living near bodies of water who haven’t observed those waters moving closer to their property. More than 35 people attended the Dec. 9 workshop at the University of Delaware Virden Center in Lewes with the somewhat lengthy title of Prioritizing Approaches for Climate Change Adaptation and Hazard Mitigation in Lewes. Its goal was to examine changes already being observed in connection with climate change and planning ways to adapt to them to protect people and property, such as improving flood-plain mapping and lifting structures out of the flood plain. … Mike Powell, a flood mitigation specialist with the Delaware Department of Natural Resources and Environmental Control, said at-risk areas must stop using flood-plain maps that depict current or past data. He said the goal is to incorporate technology as Delaware produces current and future flood-plain maps. … He said all new developments should use the most recent flood-plain mapping available. “We really recommend keeping subdivisions out of flood plains,” Powell said. He said 100-year flood plain data has proven inadequate and unsustainable. “There’s a 50-50 chance of flooding using the 10- year data,” Powell said. He said adding 1 to 2 feet of “freeboard” – increased elevation of a structure’s first story floor – above the 100-year flood plain provides additional protection. Powell said elevating structures also substantially reduces flood insurance costs. On average, flood insurance for the first floor of a structure built 1 foot above the 100-year flood-plain mark would cost $360 a year. Flood insurance built 1 foot below the mark would cost about $2,400 a year. Powell said in Lewes, East Savannah Road, Cedar Street and Cape Shores, among others, are all areas at risk of flooding. “Cape Shores is built on an eroding shoreline that’s not sustainable,” said Mark Nardi, a U.S. Geological Survey scientist. …
