Rivers and coastlines are where mapping technologies tend to run out of room. Water clarity, depth, turbidity, substrate and channel morphology all change what a sensor can see, and they change it from one reach to the next. Getting a seamless surface across the land and water interface usually means combining methods rather than trusting one.
This session covers four approaches to that problem. Speakers address topobathymetric lidar paired with sonar to recover deep channel geometry for river restoration design, an accuracy assessment of airborne bathymetric lidar flown over inland rivers where vertical performance varies with clarity and bottom reflectivity, an independent operational account of a new coastal mapping system across a growing project portfolio, and a multi-project look at how riverine topobathymetric lidar has matured and where it still struggles. Attendees will leave with a clearer sense of which method to reach for, and what to expect from each when conditions are less than ideal.
This session will include the following presentations:
The Evolution of Riverine Topobathymetric Lidar
Presented by Jackson McGraw, Dewberry
The use of aerial topobathymetric lidar to map riverine environments has emerged as an advancing technology for the acquisition of seamless, high-resolution elevation data across both land and submerged river channels, supporting a variety of applications such as flood risk assessment, habitat mapping, infrastructure management, and watershed studies.
This presentation will explore the use of riverine topobathymetric lidar through the lens of several projects, highlighting the unique challenges and lessons learned from mapping dynamic inland water systems. Topics will include technological considerations related to sensor capabilities and data processing, environmental factors such as water clarity, flow conditions, and vegetation, and the planning required to optimize acquisition in complex riverine environments. This presentation will also examine the expanding use of riverine topobathymetric lidar and discuss how advances in sensor technology and growing demand for high-quality inland hydrographic data are expanding its role in geospatial mapping and environmental decision-making.
Topobathymetric Lidar Enhanced by Sonar Support for Deep-Channel Mapping in River Restoration
Presented by Trevor Hobbs, Whiteout Solutions LLC
Accurate representation of river bathymetry is fundamental to effective stream and river restoration design, particularly in dynamic systems where channel morphology drives habitat complexity, sediment transport, and hydraulic connectivity. While topobathymetric lidar has emerged as a powerful tool for mapping shallow-water environments, its performance can be limited in deeper or highly turbid channels. Conversely, sonar-based hydrographic methods provide reliable depth measurements in deep-water zones but often lack seamless integration with surrounding floodplain and nearshore topography.
Inland Bathymetric Lidar over the Potomac River and Allegheny River
Presented by Minsu Kim, KBR / U.S. Geological Survey
Accurate and high-resolution riverine bathymetry is essential for hydrodynamic modeling, flood risk assessment, and resource management in complex systems like the Potomac River. While Airborne Bathymetric Lidar (ABL) offers an efficient means of mapping large spatial extents across the land-water interface, its vertical accuracy can vary significantly depending on water clarity, depth, and substrate composition.
This study evaluates the operational performance and vertical accuracy of an ABL survey conducted over inland waters. Teledyne’s CZMIL lidar system collected bathymetric lidar data and Teledyne’s Galaxy lidar system collected topographic lidar. To rigorously validate the Lidar-derived bathymetric surfaces across varying depth regimes, two independent truth datasets were utilized. Large amounts of Single-Beam Echo Sounder (SBES) data were collected using a remote-controlled Teledyne Z-boat. In shallow water (less than 1.5 m deep) water, waded Global Navigation Satellite System (GNSS) rover points data were collected. The ABL data were cross-referenced against the validation points to calculate standard statistical metrics, including Root Mean Square Error (RMSE), mean bias, and 95% confidence intervals. The ABL achieved a vertical RMSE of 0.11 meters and mean bias of -0.073 meters. We also present calibration with SBES data. The accuracy of topographic lidar is also presented using various Ground Check Points (GCPs). The GCPs come in the 3D context to give full 3D accuracy not just Root Mean Square Error (RMSE) of z-axis. The 3D GCPs consist of three-plane intersection points, line and plane intersection points, and line intersection points.
Our findings demonstrate the capabilities and practical constraints of airborne green-laser systems in dynamic inland river environments. The integration of waded GNSS and SBES datasets provides a robust framework for hybrid bathymetric calibration, ultimately offering geospatial practitioners clear guidelines for optimizing data fusion workflows in coastal and riverine mapping.
Operational Experience with the Leica CoastalMapper
Presented by Andres Vargas, NV5
Since taking delivery of the Leica CoastalMapper, NV5 has deployed the system across a growing portfolio of coastal and inland mapping projects, encompassing multiple survey sites and a substantial operational area. This presentation shares lessons learned from these deployments, providing an independent perspective on the system’s performance, operational strengths, and practical considerations following extended use.
The presentation will summarize the scope of deployment across our project portfolio, sharing our cumulative operational experience. Key topics will include acquisition strategies, processing workflow improvements, and observations that have helped optimize its use in a variety of survey environments. Comparisons with established topobathymetric lidar systems and project calibration results will also be presented to evaluate accuracy, consistency, and agreement across datasets.
Drawing on real-world project experience, the presentation will discuss where the CoastalMapper has proven most effective, particularly for large coastal mapping projects and extensive areas of interest where efficient coverage and integrated data collection provide significant advantages. It will also examine environments where the system is less well suited, including projects requiring very high spatial resolution or surveys conducted in poor water quality conditions, where increased noise and reduced point density can limit performance.
By sharing operational metrics, deployment experience, and practical recommendations, this presentation provides the geospatial community with an informed assessment of the Leica CoastalMapper’s capabilities, limitations, and ideal applications after extensive field use.
