Texas Parks & Wildlife Department has partnered with Texas A&M University-Corpus Christi to determine if using unmanned aircraft systems (UAS) is as effective as using planes for surveying seagrasses scarred by boat propellers.
According to the university, seagrasses serve as a refuge and nursery ground for fish, shrimp and crabs. They provide oxygen to the water column and serve as an area for growth of drift algae, a food source for shrimp, fish and crabs.
A law prohibiting the uprooting of seagrasses coastwide in Texas has been in effect since September 2013; motorboats cause propeller scarring when they drift into shallow waters and tear a trough in the bay bottom.
Dr. Michael Starek, assistant professor of engineering at the university, has been analyzing UAS images and data collected from flights in December above Redfish Bay’s seagrasses.
Using piloted aircraft flying at an altitude of about 2,000 feet, TPWD has conducted aerial surveys since 2007, according to Faye Grubbs, Upper Laguna Madre Ecosystem leader with TPWD.
This project will compare the output from each method and analyze the costs of processing and ease of mobilization.
“This experiment showed that with proper flight planning for weather conditions, mapping of prop scars with a small UAS can be a viable alternative to more costly, piloted airborne surveys,” Starek says. “Results from the flights show impressive spatial fidelity in the UAS-collected imagery. Pixel resolutions down to one inch will allow mapping of seagrass impacted by prop scarring at very fine spatial detail previously unattainable.”
Although the results show the capabilities, Starek says UAS technology still has to evolve both in platform endurance and in regulations in order to allow the systems to fly autonomously over much larger areas, such as an entire bay system.
“In the not-too-distant future, I can foresee the day when a fleet of small UAS equipped with cameras can routinely map an entire bay system at a fraction of the cost for traditional piloted airborne surveys,” he says. “The potential for UAS technology is immense.”