New aerial photos will help with lake management

September 30, 2021

Penticton Herald – September 30, 2021

New high-resolution aerial photos of the bottom of Okanagan Lake will help in weed eradication, habitat protection, and flood prevention, water managers say.

The pictures provide a clear look into the lake to a depth of 10 metres all along the shoreline of the 90-km-long lake from Vernon to Penticton.

Although the images, based in part on data that was retrieved from a plane crash, are still being processed, they’re expected to find application as soon as next month when water managers begin deciding how to deploy vessels that yank weeds from the lake bottom.

“The milfoil team is currently preparing for rototilling season, starting in mid-October,” James Littley, operations manager for the Okanagan Basin Water Board, states in a newly-released report.

“We anticipate using the new orthophotos (to) map aquatic plant beds hopefully in time to inform our upcoming de-rooting season,” Littley says.

Quantum Spatial, the company engaged by the Okanagan Basin Water Board, prepared the 3D maps and photos in a $1.45 million process that began in 2018.

Aircraft equipped with LiDAR (light detection and ranging) overflew the lake and upland areas repeatedly to gather the necessary data. But one of the aircraft crashed on the way back to Calgary on Aug. 1 of that year, and pilot Daniel Thibeault and technician Levi VandenBrink were killed.

The LiDAR hard drive was recovered from the plane’s wreckage and, although damaged, was still able to yield data used to prepare the new maps.

Because the maps and photos give clear underwater views, registering the depth of the lake at different levels along the shoreline, officials say they will help with seasonal flood-protection efforts by identifying areas most at risk during times of heavy rainfall and quick snowmelt.

If LiDAR-generated flood maps had been available in 2017, the damage caused by record high lake levels might not have been as severe as it proved to be, Shaun Reimer, the provincial official who manages the level of the lake, said when the mapping project was launched in 2018.

“It would have helped local governments identify the most vulnerable places, and it would have helped to prioritize resources, and I think that would have been very useful,” Reimer said at the time.

Prior to the LiDAR project, existing floodplain maps covered only a few areas of the lake and were about 25 years old.

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