Mapping Seafloor Relative Reflectance and Assessing Coral Reef Morphology with EAARL-B Topobathymetric Lidar Waveforms

Abstract

Topobathymetric lidar is becoming an increasingly valuable tool for benthic habitat mapping, enabling safe, efficient data acquisition over coral reefs and other fragile ecosystems. In 2014, a novel topobathymetric lidar system, the Experimental Advanced Airborne Research Lidar-B (EAARL-B), was used to acquire data in priority habitat areas in the U.S. Virgin Islands (USVI), spanning the 0–44-m depth range. In this study, new algorithms and procedures were developed for generating seafloor relative reflectance, along with a suite of shape-based waveform features from EAARL-B. Waveform features were then correlated with percent cover of coral morphologies, domed and branched, and total cover of hard and soft corals. Results show that the EAARL-B can be used to produce useful seafloor relative reflectance mosaics and also that the additional waveform shape-based features contain additional information that may benefit habitat classification—specifically, to aid in distinguishing among hard corals and their coral morphologies, domed and branched. Knowing the spatial extent of changes in coral communities is important to the understanding of resiliency of coral reefs under stress from human impacts.

Elevated nutrients and herbivory negatively affect Dictyota growth dynamics

“…These sites do not differ greatly in measured mean physical or biological characteristics, except for differences in depth and distance from shore (Fig. 1; Smith et al (Fredericks et al 2015, Wilson et al 2019 2008). These sites were chosen largely because they have been used as part of long-term, high-frequency data collection efforts of the Territorial Coral Reef Monitoring Program and provide a wealth of ancillary data (Table 1).…”

“…Study sites and their mean depths in St. Thomas, United States Virgin Islands. Background bathymetry provided by airborne light detection and ranging(Fredericks et al 2015, Wilson et al 2019…”

ICESat‐2 Elevation Retrievals in Support of Satellite‐Derived Bathymetry for Global Science Applications

“…The (Slocum, 2020;Wilson et al, 2019), indicated that the overall level of seafloor elevation change in the nearshore areas of our study site is small enough (µ = 11 cm, σ = 16 cm, prehurricane versus posthurricane lidar elevation difference in the vicinity of Buck Island) in comparison to typical SDB accuracies that the airborne bathymetric lidar can be used as a suitable reference data set.…”

“…The ICESat-2 ATL03 geolocated data for two ATLAS beams (GT3R and GT1R) collected from a descending track on It is important to note that, during the four-year time interval between the acquisition of the airborne bathymetric lidar data and the ICEsat-2, Landsat 8, and Sentinel-2 data collections, the site was impacted by Hurricane Maria (September 20, 2017). Analysis of nearshore seafloor change in this general area conducted by our research group as part of separate studies (Slocum, 2020;Wilson et al, 2019), indicated that the overall level of seafloor elevation change in the nearshore areas of our study site is small enough (µ = 11 cm, σ = 16 cm, prehurricane versus posthurricane lidar elevation difference in the vicinity of Buck Island) in comparison to typical SDB accuracies that the airborne bathymetric lidar can be used as a suitable reference data set.…”

Classification of Land-Water Continuum Habitats Using Exclusively Airborne Topobathymetric Lidar Green Waveforms and Infrared Intensity Point Clouds

“…Since all objects present in the cone illuminated by the laser reflect some light towards the sensor, they all contribute to the recorded waveform's shape [28]. Each element of the landscape/seascape is therefore characterized by the shape of its component in the waveform, which can be used for land or sea cover detection and classification [27,29,34,41]. In this work, backscattered intensities are converted into pseudo-reflectances by dividing them with the emitted pulse's intensity.…”