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County using laser to contest FEMA maps
By EDIE GROSS © St. Petersburg Times, published August 2, 1998 But Carter, a rather busy adjunct professor at the University of Florida's department of civil engineering, does not have that kind of money or time. Instead, he has a better idea. Carter and fellow UF professor Ramesh Shrestha plan to fly over Pinellas County this month, mapping its 309 square miles with a laser. The data collected with the new technology will be turned over to the Federal Emergency Management Agency, which has been revising the county's flood maps amid much criticism from local officials and residents. FEMA has not promised to change its controversial maps, which angered many residents by placing them in flood zones. But it has said it will look carefully at the new information. "There's no way to make the maps 100 percent accurate," FEMA spokeswoman Mary Hudak said. "By its very nature, it's a contentious issue, but we try to work responsibly with local government." Pinellas County has agreed to pay UF $850,000 for the study. The old-fashioned way of surveying the county, by hand with a level device, would take years, require more money and would not produce results as accurate as the laser technology, Carter said. Even the more recent technique of photogrammetry, where overlapping photos are turned into a three-dimensional image, would take years and cost $4-million to $5-million, county officials estimate. "If the weather cooperates, we'll map the whole county in one week" with the laser, Carter said. "Eventually it will become a very routine mapping process, but it'll be faster, more accurate, cheaper and better." No guessworkThe results, which will be given to FEMA by Sept. 15, may end months of arguing between the federal agency and those who live in Pinellas County FEMA presented a draft set of flood maps to the county earlier this year, the first new maps since 1983. But some local officials were disappointed that the maps did not use flood information provided by the county. Residents in the northern half of East Lake were concerned because FEMA drew most of them into a flood zone without determining how high flood waters would actually rise there. And coastal homeowners in the southern part of the county felt FEMA overestimated the dangers of living on the beach. Overall, many property owners felt the proposed maps would force them to pay higher flood insurance rates and make it more difficult for them to sell their homes. FEMA defended its maps, saying it used available historical and topographical data to determine which parts of Pinellas County belonged in flood zones. FEMA said it estimated flooding levels in the northern half of East Lake because it did not have enough money to continue a detailed study there. Money in the federal flood insurance fund has to cover studies throughout the country, so officials focus on more-developed urban areas rather than less-developed suburban areas. If funds get low and the agency has to estimate flood levels, it errs on the side of caution, FEMA officials have said. Many hope the study by the UF professors will leave no need for guesswork. "They (FEMA) recognize the information they have is inferior to what they expect to get because they've never done a survey of the topographical and hydrological elements of East Lake," said Ridgemoor resident Don Flynn, one of the more vocal opponents of FEMA's proposed maps. "This is the first time we'll ever have information that relates to the elements of land in East Lake done on a scientific basis with an accuracy within 6 inches," he said. "I'm absolutely delighted." Carter and Shrestha used the laser technology in 1996 to map 300 miles of beaches along the Panhandle, a year after those areas were rocked by Hurricane Opal. The duo did the work in two hours for $78,000, Carter said. It took Florida Department of Environmental Protection teams several months to complete the work with older technology at a cost of more than $300,000. When results between the two studies differed, it was only by a few centimeters. Importance of accuracyMapping all of Pinellas County will be the biggest job the professors have completed with the Airborne Laser Terrain Mapper, a $1-million piece of equipment created by a Canadian company called Optech "Expensive but small. Kind of like a diamond ring," Carter said. Here's how the technology works: A small airplane will fly about 2,000 feet above the ground in Pinellas County. Its position will be recorded by satellites. The laser equipment, which weighs about 20 pounds, fires about 5,000 pulses per second through a small hole in the floor of the airplane. Each pulse of infrared light strikes an object somewhere on the ground. Then it bounces back to the plane. The laser pulses are beamed to the ground in a saw-tooth pattern, covering as much ground as possible. A computer on the plane measures how long it takes for the pulse to hit something and come back. Keeping track of the plane's speed and altitude, the computer can figure out the lay of the land. Engineers plan to survey some of the terrain from the ground to make sure the laser technology is accurate. "We don't want any doubts as to the accuracy of the information," said Elmer Spence, an engineer in the surface water division of the county's Public Works Department. He is coordinating the project with Carter and Shrestha. "That accuracy is very important to people and I think FEMA should think it's very important to people," Spence said. "It's their reputation on the line." Originally, the county had until the end of April to comment on FEMA's proposed maps. But opposition was so heavy in Pinellas County that FEMA gave officials here until the end of September to come up with significant new information that the agency could consider. Carter said he and his colleagues told FEMA about the technology about 18 months ago. FEMA officials passed that information to the county because they knew the laser mapping could be done quickly. "There's no way new topography could've been provided to them within the prescribed time limit using any other technology," Spence said. The maps will provide more than just flood elevation data, County Administrator Fred Marquis said. The county can use the information for drainage studies and road surveys. Some money spent on the study was pulled from accounts for studying drainage in Pinellas County and funding a hurricane preparedness update. The county's old maps, dating to the 1970s, featured contour lines for the land every 4 feet. The new ones will have lines every foot, Marquis said. "What we'll end up with is a new set of maps with 1-foot contours, extremely accurate," he said. "This gives us very current, up-to-date aerials." The technology is a distant cousin of the lasers beamed from Hawaii to the moon and back to measure distance, a NASA project Carter was involved in during the 1970s. He is quick to point out that the laser used to map Pinellas County is not the "death ray," as one Hawaiian television reporter once called it. It is safe for the eyes, and chances are, no one will notice it, he said. Ridgemoor resident Mark DeHarde said he understands FEMA's need to finish the maps soon. But he was pleased to hear the agency would wait for the new, more accurate information provided by the laser mapping. "I'm sure (homeowners) want their property to be judged based on what it physically is, not what it's thought to be," he said. There are no guarantees that FEMA will alter its flood maps based on the new information. But county officials who disagreed with FEMA's last set of maps wanted to try something, Marquis said. "FEMA hasn't promised us anything. They may come right back and say, "Thank you very much. The new data just proves our point,' " Marquis said. "They just won't implement the current maps until they see our new data."
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f professor Bill Carter had several million dollars at his disposal, a good pair of sneakers and nothing better to do, he could spend a few years trekking through Pinellas County, surveying its terrain.
