Mapping river bathymetries: Evaluating topobathymetric LiDAR survey

Abstract

Advances in topobathymetric LiDARs could enable rapid surveys at sub‐meter resolution over entire stream networks. This is the first step to improving our knowledge of riverine systems, both their morphology and role in ecosystems. The Experimental Advanced Airborne Research LiDAR B (EAARL‐B) system is one such topobathymetric sensor, capable of mapping both terrestrial and aquatic systems. Whereas the original EAARL was developed to survey littoral areas, the new version, EAARL‐B, was also designed for riverine systems but has yet to be tested. Thus, we evaluated the ability of EAARL‐B to map bathymetry and floodplain topography at sub‐meter resolution in a mid‐size gravel‐bed river. We coupled the EAARL‐B survey with highly accurate field surveys (0.03 m vertical accuracy and approximately 0.6 by 0.6 m resolution) of three morphologically distinct reaches, approximately 200 m long 15 m wide, of the Lemhi River (Idaho, USA). Both point‐to‐point and raster‐to‐raster comparisons between ground and EAARL‐B surveyed elevations show that differences (ground minus EAARL‐B surveyed elevations) over the entire submerged topography are small (root mean square error, RMSE, and median absolute error, M, of 0.11 m), and large differences (RMSE, between 0.15 and 0.38 m and similar M) are mainly present in areas with abrupt elevation changes and covered by dense overhanging vegetation. RMSEs are as low as 0.03 m over paved smooth surfaces, 0.07 m in submerged, gradually varying topography, and as large as 0.24 m along banks with and without dense, tall vegetation. EAARL‐B performance is chiefly limited by point density in areas with strong elevation gradients and by LiDAR footprint size (0.2 m) in areas with topographic features of similar size as the LiDAR footprint. © 2018 John Wiley & Sons, Ltd.

Concept and Performance Evaluation of a Novel UAV-Borne Topo-Bathymetric LiDAR Sensor

“…In this Section, we provide a summary of related work in the context of UAV-based optical remote sensing of coastal and inland water areas, focusing on the derivation of bathymetry. For the sake of completeness, we first briefly discuss passive image-based techniques, both via multimedia photogrammetry [10] and spectrally based depth estimation [11], but mainly concentrate on bathymetric LiDAR [1] in general and small-footprint topo-bathymetric LiDAR for inland water applications in particular [12,13]. Furthermore, we present recent validation and comparison studies on subject matters as our contribution also focuses on sensor evaluation.…”

Remote sensing of river corridors: A review of current trends and future directions

“…Alternatively, green wavelength ALS can collect bathymetry over lengths from one to tens of kilometres (Hilldale & Raff, ; Kinzel, Legleiter, & Nelson, ; Kinzel, Wright, Nelson, & Burman, ), yet footprint size that reduces accuracy and point density are limiting factors (Tonina et al, ). Despite these methods being available, the extra challenge in obtaining them makes bathymetric analysis less prominent in the literature.…”

Evaluating the performance of topobathymetric LiDAR to support multi‐dimensional flow modelling in a gravel‐bed mountain stream

“…Two morphologically different reaches, a complex and simple reach, of the Lemhi River were selected as study sites ( Figure 1) (Tonina et al, 2018). The complex upstream study reach is 230 m long, 10m wide, and has an average bed slope of 0.75%.…”

“…LiDAR survey The EAARL-B system surveyed the entire Lemhi River from Leadore to the confluence with the Salmon River on the afternoons of 25-27 October 2013 during ideal conditions of clear water and minimum foliage on the riparian vegetation. EAARL-B LiDAR full-waveform returns were processed using a combination of the Airborne Lidar Processing System (ALPS), Applied Imagery's Quick Terrain Modeler, and ESRI's ArcMap 10.2 (Tonina et al, 2018). The resulting filtered point cloud of the EAARL-B system had a point density of approximately 1 pointm À2 over the submerged topography of the entire Lemhi River.…”