Evaluating Collection Parameters for Mobile Lidar Surveys in Vegetated Beach-Dune Settings

Abstract

The goal of this Coastal and Hydraulics Engineering Technical Note (CHETN) is to compare collection parameters and gridding techniques for mobile lidar surveys of beach-dune systems in the northern Outer Banks, NC.

Alongshore Variable Accretional and Erosional Coastal Foredune Dynamics at Event to Interannual Timescales

“…These morphologic behaviors have been well documented on the northern Outer Banks, especially via a long‐term monitoring program at the U.S. Army Engineer Research and Development Center (ERDC) Field Research Facility (FRF) in Duck, NC (Birkemeier & Forte, 2019; Crowson et al., 1988). Data from the FRF shows a highly 3D beach topography throughout the region that evolves on ∼ daily timescales associated with beach cusp evolution (O’Dea & Brodie, 2019), intermittent storm‐driven beach and dune erosion (Brodie, Conery, et al., 2019), and prevalent sand mobilization from wind‐driven processes that contributes to dune growth (Conery, Brodie, et al., 2020). This study focuses on a 6.5 km stretch of beach within the town of Duck (Figure 1), including the FRF property (Zone 2 in Figure 1a).…”

“…The filtered data is gridded onto a 0.25 m grid in both the cross-shore and longshore directions for the entire 6.5 km stretch of coast to generate a regional digital elevation model (DEM) for each data collection (e.g., Figure 3). A secondary filter is further applied on each gridded DEM to remove cells with sparse data points near the dune crest where vegetation can limit accurate detection of the bed (e.g., Conery, Cohn, et al, 2020). Errant returns are additionally removed from the gridded surface using a cross-shore Gaussian smoother.…”

“…Based on typical driving speeds (∼10 km/hr) and height of the vehicle (∼2.5 m), data density is roughly 100 pts/m 2 between overlapping framescans within about 50 m of the van. An analysis of the scanner performance with these settings for resolving beach and dune topography is described in Conery, Cohn, et al (2020). Mean vertical errors using gridded CLARIS outputs relative to RTK GPS measurements are typically <0.05 m, making the data from this system suitable to resolve both accretional and erosional processes within coastal dunes in locations with sufficient point density.…”

Evaluation of Unmanned Aircraft Systems for flood risk management : results of terrain and structure assessments

“…The entirety of the FRF beach-dune system was scanned with the Coastal Lidar and Radar Imaging System (CLARIS), a van-mounted Riegl VZ-2000 terrestrial lidar scanner coupled to an IX-Blue ATLANS-C inertial navigation system on 15 June 2017. The system and its operation are described in Spore and Brodie (2017), Spore et al (2019), andConery et al (2020). The system was capable of collecting elevation data from the approximate location of the dune crest to the shoreline utilizing a mobile 3D scanning pattern (radar mode) with similar accuracies described in Conery et.…”

“…The system and its operation are described in Spore and Brodie (2017), Spore et al (2019), andConery et al (2020). The system was capable of collecting elevation data from the approximate location of the dune crest to the shoreline utilizing a mobile 3D scanning pattern (radar mode) with similar accuracies described in Conery et. al.…”