Comparative analysis of sandy beach and foredune geomorphic change measurements from Apple LiDAR and small-unoccupied aerial systems

Abstract

Sandy beach and foredune environments are common throughout the Great Lakes region and world. Coastal landscapes are dynamic and vulnerable due to water level fluctuations, high-energy storm events, and human disturbance. Standard methods for measuring geomorphic transformations over time include small-unoccupied aircraft systems (sUAS), but it is costly and spatiotemporally limited. To document the utility of the Apple LiDAR for coastal mapping, we quantitatively evaluated the accuracy of Apple’s light imaging detection and ranging (LiDAR) scanner in comparison to high precision RTK-GPS paired with sUAS to map geomorphic change at Port Crescent State Park in Lake Huron. Benchmark elevations were measured via RTK-GPS and the sUAS and Apple LiDAR elevation measurements were compared to these benchmark elevations to calculate percent errors. Low percent errors were documented, which allowed for further analysis of spatial differences between the two methods in both mapping morphology at a single instance in time as well as change over several months (in response to wave events). Spatial patterns are consistent between the DEMs, and large geomorphic transformations, such as the formation of a berm, were detected in both DODs. Differences between the two survey elevation models arise due to the Apple LiDAR’s capability to detect the finer-scale sandy contours with the foredune, suggesting the scanner can be used to map in areas with rugged topography and/or vegetation presence. Coastal managers can utilize the Apple LiDAR as an accessible way to map geomorphic change quickly and accurately, which can promote the development of proactive and resilient management plans.