Data collection tools for river geomorphology studies : LiDAR and traditional methods

Abstract

The purpose of this review is to highlight LiDAR data usage for geomorphic studies and compare to other remote sensing technologies. This review further identifies survey efficiencies and issues that can be problematic in using LiDAR digital elevation models (DEMs) in completing surveys and geomorphic analysis. US Army Corps of Engineers (USACE) geospatial data collection guidance (EM 1110-1-1000) (USACE 2015) aligns with the American Society for Photogrammetry and Remote Sensing Positional Accuracy Standards for Digital Geospatial Data (ASPRS 2014). Geomorphic assessment technologies are rapidly evolving, and LiDAR data collection methods are at the forefront. The FluvialGeomorph (FG) toolbox, developed to support USACE watershed planning, is a recent example of the use of LiDAR high-resolution terrain data to provide a new, efficient approach for rapid watershed assessments (Haring et al. 2020; Haring and Biedenharn 2021). However, there are advantages and disadvantages in using LiDAR data compared to other remote sensing technologies and traditional topographic field survey methods.

Remote sensing tools to support ordinary high water mark delineation

“…Once a DEM tile is downloaded from the USGS National Map, check the elevations along the channel bed to make sure it is not hydro-flattened. Hydro-flattening will show up as a stairstep of elevations along the stream instead of the actual elevations (Haring 2019;Haring 2021). The DEM should also be checked to see if the elevation is in meters or feet.…”

“…There are many factors that influence the accuracy of the lidar data. More detailed information on drivers of lidar accuracy and coverage can be found in Haring et al (2019) and Haring (2021). The profile shows the location of field surveyed crosssection locations 121 (Figure 9, red circle).…”

“…When using remotely sensed terrain data for OHWM determinations, accuracy in identifying the physical characteristics of the OHWM is generally dependent upon the resolution of the data. Haring (2019) and Haring (2021) describe the issues with interpreting high-resolution terrain data (lidar) and the difficulties with existing resolution in off-the-shelf data. Resolution and extent of existing terrain data affects both the time required to produce a usable analysis approach as well as the usefulness in any OHWM determinations resulting from the analysis approach.…”