Evaluating the ability of several commercially available UASs to capture topographic complexity typical of estuarine bluff shorelines in North Carolina

Abstract:

Over the past 50 years the bluff shorelines of the Albemarle-Pamlico estuary in North Carolina have generally been eroding due to storm-generated forces. In September 2018, waves generated by Hurricane Florence eroded the east facing bluffs in the estuary causing property losses for over a hundred residents, many of which are without recovery measures. Considering the importance of bluffs for development along the estuary, local officials are interested in better understanding erosion rates with the goal of developing a comprehensive bluff protection scheme. With the recent advancements of Unmanned Aerial Systems (UAS) technologies and structure-from-motion (SfM) techniques, accurate and precise 3D measures of erosion along bluffs can be more easily quantified. In this study, we compare 3D point clouds produced from five different commercially available UASs as well as drone and mobile based LiDAR systems with terrestrial LiDAR. A Monte-Carlo approach is used to consider sources of survey error and spatially variable precision in the UAS surveys. Preliminary results suggest that depending on the topographic complexity, UAS and SfM-derived 3D point clouds can deviate from the terrestrial LiDAR within ±14 cm vertically. The results from this study will provide a framework for conducting quality and consistent surveys used to measure short-term bluff erosion.