World

Push to map the bottom of Great Lakes gains momentum

MADISON, Wisconsin: An official from the Great Lakes Observing System is leading a campaign to map every meter of the lakes’ bottom that could pinpoint hundreds of underwater shipwrecks, illuminate topographical features, and locate infrastructure.

Jennifer Boehme, executive director of the Great Lakes Observing System, says the map will also help ships avoid submerged hazards, identify fisheries, and inform erosion, storm surge, and flooding models as climate change intensifies.

Boehme grew up scouting beaches around her home in St. Petersburg, Florida, for rocks, sand dollars, and coquina mollusks the ocean gave up. Now, 40 years later, Boehme wants to launch another treasure hunt to the bottom of the lakes.

The Great Lakes Observing System, a non-profit that manages data from a network of lake observers and makes it easily accessible, said only a fraction of the Great Lakes’ bottom has been mapped, and those low-resolution charts were completed decades ago.

The National Oceanic and Atmospheric Administration certified the Great Lakes Observing System in 2016 as meeting federal standards for data gathering and management, allowing the federal government to use its data without further vetting.

The organization has been pushing since 2018 to create high-resolution maps of all five Great Lakes bottoms, but that is a daunting task. The lakes cover 94,250 square miles, an area larger than the state of Kansas. Depths range from 210 feet in Lake Erie to more than 1,300 feet in parts of Lake Superior.

The idea is gaining traction since technology has improved and scientists have completed high-resolution mapping of Florida coastlines and the Gulf of Mexico over the last three years. Two congressional representatives from Michigan, Republican Lisa McClain, and Democrat Debbie Dingell introduced a bill this year that would allocate US$200 million to map the Great Lakes bottoms by 2030.

Boehme does not think the bill will get traction in an election year, but the Great Lakes Observing System is still working toward its 2030 mapping goal. The group holds an annual conference in Traverse City, Michigan, to discuss progress and test mapping technology.

The last effort to map the lakes came in the 1970s. Fast forward to nearly half a century. Now, scientists and engineers have an array of new mapping tools.

One is multibeam sonar. Rather than sending a single sound wave, these systems bounce potentially hundreds off the bottom. The technology is so sensitive it can detect air bubbles in the water, according to NOAA.

The only drawback is that systems need to be mounted on submersibles or towed under ships to obtain high-resolution images in deep water.

Another tool is laser imaging, where scientists measure how long it takes for a laser beam fired from a plane to reach an object and bounce back, resulting in three-dimensional imaging of bottom topography.

Steven Murawski, a biological oceanographer at the University of South Florida, who has done extensive bottom mapping of Florida’s coast and in the Gulf of Mexico said The Great Lakes map would provide fuller images of bottom features that have changed in the last 50 years due to erosion and shifting sands, giving navigators new depth findings that would improve shipping safety.

A map also would help predict how bottom features affect storm surges and flooding as climate change continues, which he said would be invaluable information for insurance companies and municipal planners.

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