Application of UAV Structure-From-Motion Photogrammetry to a Nourished Beach for Assessment of Storm Surge Impacts, Pinellas County, Florida

Barrier island beaches provide important protection, but human development, loss of natural cover, hurricanes, and tropical storms have contributed to widespread beach erosion. Some coastal regions resort to jetties, shore protection structures, and beach nourishment, whereby offshore or other nearby sediment sources are mined and added to the beach. These projects are costly, and their effectiveness must be closely monitored. This article investigates the ability of photogrammetry from an unoccupied aerial vehicle (UAV) to quantify geomorphic changes of the subaerial section to a newly nourished beach. On October 10, 2018, Hurricane Michael moved up the Gulf of Mexico past Tampa Bay, coinciding with an ongoing nourishment project at Indian Rocks Beach. We conducted UAV and ground surveys before and after the hurricane passage and compared point clouds and across-shore profiles at three locations. We compare observed erosional regimes to probabilistically forecast erosional regimes and found they were only minimally present, perhaps reflecting the recent sand additions. An average volume loss of ~31 m3/m was measured across the three studied sections.