Laser Mapping System Could Speed Post-Hurricane Rebuilding Efforts

May 5, 1998

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GAINESVILLE — A state-of-the-art laser mapping system could save the state millions of dollars in surveying expenses and dramatically accelerate Florida’s efforts to rebuild its beaches after major hurricanes, say two University of Florida professors.

At $1 million, the system isn’t cheap, say civil engineering professors Bill Carter and Ramesh Shrestha. But it could slash the expense of gauging damages to beaches after hurricanes more than 90 percent and speed up the process from months to hours, they say.

“You could map all the beaches in Florida to prepare for a hurricane and, after the hurricane, re-map the beaches, and within hours you’d know how much work had to be done,” Carter said. “You could get your contracts out, get your contractors in and fix the beaches so people could get back to normal life as quickly as possible.”

The first step in rebuilding beaches after hurricanes is to measure sand loss and assess other damages, such as new coves or inlets. Florida and other states have long gone about the work using traditional land-based surveying, which is time-consuming and can delay the start of beach renourishing or other recovery work by weeks or months.

Carter and Shrestha say they adapted a piece of high-tech equipment called the Airborne Laser Terrain Mapper to do the surveying more accurately in a matter of hours — with the aid of software Shrestha developed at UF.

Built by a Canadian company called Optech, the mapper draws on technology originally developed by NASA to map ice flows in Greenland, Carter said.

Aloft in a small plane, it has a highly accurate pulse laser that emits 5,000 pulses of light each second toward the beach. The pulses hit and scatter back, allowing the system to gauge the distance between the plane and the beach. A Global Positioning System and other equipment determine the plane’s location and pitch.

Shrestha and Carter leased the system for a week in 1996 to test its capabilities on Panhandle beaches damaged by Hurricane Opal.

Sending it aloft in plane borrowed from the Florida Department of Transportation (DOT), they surveyed about 300 miles of beaches in six counties. Optech’s computers crunched the raw data, with UF computers and software refining it further.

The result was a digital map of the beach. In graphic form, the map mimics what a passenger in the plane would see. But it contains data on the latitude, longitude and height of millions of different points on the beach — measurements repeated every few meters, impossible through traditional surveying methods.

Shrestha said the Florida Department of Environmental Protection (DEP) spent $330,000 surveying 30 miles of beaches damaged by Opal, whereas the researchers’ cost for the 300 miles, not including the system’s $1 million price tag, was $37,000. The DOT and DEP co-sponsored the project.

“The state survey teams spent about three months, working six days a week, 10 to 12 hours a day, to survey the beach, and then they had cross sections every thousand feet,” Shrestha said. “And we, in an hour, mapped the whole beach with measurements every two meters.”

Shrestha said the researchers delivered the data to DEP and have been told workers are using it as part of rebuilding efforts.

The mapping system has other applications, including highway construction mapping. At the researchers’ urging, the DOT sought to buy the system last year, but it was cut from the budget at the last minute, they said. UF also has submitted proposals to the state and the National Science Foundation to buy the system.

“The state needs a system someplace, and one in the state of Florida would pretty much do everything you need to do,” Carter said.