29 Apr 2025

Tools for Inlet Geomorphic Mapping: An Overview and Application at East Pass, Florida and Fire Island Inlet, New York

Abstract: The purpose of this Coastal and Hydraulics Engineering Technical Note (CHETN) is to highlight emerging tools for inlet geomorphic mapping and describe the workflows used to implement the tools. The Coastal Inlets Research Program (CIRP) maintains the US Coastal Inlets Atlas, which houses technical information (e.g., physical processes, navigation channel position, federal authorization for management purposes) on tidal inlets. Future expansion of the Atlas should include ready-made products that address a call from coastal inlet managers and practitioners to map inlet geomorphic change and features more accurately. The methods and workflows demonstrated in this document represent the first step towards expanding the US Coastal Inlets Atlas.

9 Aug 2021

Simultaneous Mapping of Coastal Topography and Bathymetry from a Lightweight Multicamera UAS

Abstract: A low-cost multicamera Unmanned Aircraft System (UAS) is used to simultaneously estimate open-coast topography and bathymetry from a single longitudinal coastal flight. The UAS combines nadir and oblique imagery to create a wide field of view (FOV), which enables collection of mobile, long d Coastal mapping, multiview stereo (MVS), nearshore morphology, remote sensing, structure from motion (SfM), Unmanned Aircraft Systems (UAS)well timeseries of the littoral zone suitable for structure-from motion (SfM), and wave speed inversion algorithms. Resultant digital surface models (DSMs) compare well with terrestrial topographic lidar and bathymetric survey data at Duck, NC, USA, with root-mean-square error (RMSE)/bias of 0.26/–0.05 and 0.34/–0.05 m, respectively. Bathymetric data from another flight at Virginia Beach, VA, USA, demonstrates successful comparison (RMSE/bias of 0.17/0.06 m) in a secondary environment. UAS-derived engineering data products, total volume profiles and shoreline position, were congruent with those calculated from traditional topo-bathymetric surveys at Duck. Capturing both topography and bathymetry within a single flight, the presented multicamera system is more efficient than data acquisition with a single camera UAS; this advantage grows for longer stretches of coastline (10 km). Efficiency increases further with an on-board Global Navigation Satellite System–Inertial Navigation System (GNSS-INS) to eliminate ground control point (GCP) placement. The Appendix reprocesses the Virginia Beach flight with the GNSS–INS input and no GCPs.