72 so he keeps a close eye on the wind forecasts. “Ninetyfive percent of our flights are over water, and I haven’t lost a drone to the water yet,” he said. “It’s nothing short of a miracle at this point.” To process and aggregate drone images, Berry uses the cloudbased drone mapping software Site Scan for ArcGIS. After he completes each flight, he uploads images to the cloud while he’s driving to the next site. “By lunchtime, photos are ready to look at and share with the rest of the group,” Berry said. The team is building a test for machine learning in hopes of automating classification and change detection. It’s really nice to have the imagery. It’s easy to write reports, do science experiments, or analyze data. When you see these big green mats on pristine beaches—bigger than two years ago— it’s got a shock value. — Brandon Berry, ecological researcher at TERC Tracking More Clearly What started with a few drone tests turned into a sizable drone program. “Previously, we had to track the growth of algae based off small subsamples,” Berry said. “Now, with the drone work, we can track algae much more spatially. We’re capturing sites with hundreds of meters of shoreline, and it’s easier to track algae growth.” With the success of monitoring metaphyton, the program expanded to monitor attached algae known as periphyton. The periphyton grows on rocks and other objects near shore. “We’ve tested drones and have proven they work,” Berry said. “We’re now combining everything into a big nearshore monitoring program.” The program uses a helicopter to regularly fly around the perimeter of the lake, which it can do in an hour. That flight gives the team data about the entire shoreline to pick out any problem spots where algae has popped up. The drone flights monitor specific sites with high-resolution imagery to track the rate of algae growth. In addition to routine monitoring, TERC’s graduate students, post-doctoral scholars, visiting scientists, and professional staff conduct ongoing research funded by national and state agencies. Research topics include invasive species control, lake These drone-derived image maps taken on the north shore of Lake Tahoe show the periphyton (attached algae) problem. On the left is an orthomosaic created with Site Scan for ArcGIS. On the right is a classified image with periphyton in bright green. Photo by Brandon Berry, courtesy of the Tahoe Environment Research Center.
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