Applications of Remotely Sensed TopoBathymetric Data – I

Presentations in the session will highlight acquisition, processing, and workflows for mapping of the coastal and nearshore environment with satellite derived bathymetry, aerial topobathymetric lidar, SAR, and other sensors.

11:00 AM – 11:15 AM – Coherent Topo-Bathy in One Pass – Revisiting Shipwrecks and Riverbends in the Great Lakes and Beyond: A Closer Look at Bathymetric Resolution and Geometric Coherence

Repeatable high‑resolution mapping of riverine environments and coastal margins requires airborne lidar systems that can capture coherent topography and bathymetry in a single pass, across varying flight geometries and water‑column conditions. We present and evaluate Fathom, an integrated topo‑bathy architecture that couples a 60 kHz bathymetric laser array (effective 240 kHz sounding rate) with a 1.5 MHz topographic channel through a unified calibration of both optical paths.  
 
Test flights over riverbed and Georgian Bay (Ontario) at two survey altitudes demonstrate sub‑decimeter vertical coherence between strips, comprehensive water‑surface detection, and depth penetration consistent with Kd × Dmax ≈ 3.2. Relative to historic CZMIL SuperNova transects, Fathom’s narrower beam divergence and tighter swath—together with its denser point cloud—more confidently resolve navigation hazards such as shipwreck masts and reveal intricate river‑bed relief that raster smoothing previously obscured, illustrating gains in bathymetric resolution and repeat‑survey fidelity.  
 
The presentation details the hardware layout, simultaneous geometric and radiometric calibration, multichannel waveform processing, shallow‑water signal deconvolution, and a surface‑slope‑adaptive refraction correction. Measured accuracies satisfy IHO S‑44 Order 1a bathymetry and USACE QL0B topography, indicating that a single‑flight, dual‑channel lidar can meet modern standards for hydrographic charting, infrastructure monitoring, and rapid response in inland and coastal settings.

Brandon Maingot, Teledyne Geospatial

11:15 AM – 11:30 AM – Advancing Shallow Water Bathymetry Through Laser and Hyperspectral Fusion

Mapping shallow aquatic environments with high fidelity remains a persistent challenge in geospatial science. This presentation introduces an integrated approach that combines airborne laser bathymetry (ALB) with hyperspectral imagery (HSI) to enhance accuracy, depth estimation, and bottom-type classification in coastal and freshwater systems.

By fusing ALB’s geometric precision with HSI’s rich spectral sensitivity, we demonstrate how this multi sensor technique resolves water column attenuation effects, improves substrate discrimination, and enables sub-meter bathymetric modeling in depths less than 10 meters. Using calibrated reflectance algorithms and novel fusion pipelines, benthic features such as sand, vegetation, and rock are distinguished with high confidence—even under turbid conditions.

Key components include:

• Spectral-band optimization for water transparency and bottom albedo
• Joint waveform analysis to correlate HSI reflectance with bathymetric returns
• Machine learning classifiers trained on fused spatial–spectral datasets
• Field validation using UAV-based systems over Icelandic fjords and tropical estuaries
• This multispectral synergy offers a transformative method for monitoring coastal erosion, submerged habitats, and sediment transport—especially in regions where traditional sonar and visual mapping are limited.

Steve du Plessis, ITRES Research Limited

11:30 AM – 11:45 AM – Comprehensive Seafloor Mapping of Florida’s Coastal Waters Using Topographic-Bathymetric Lidar and Multibeam Sonar Technology

The Florida Seafloor Mapping Initiative (FSMI), led by the Florida Department of Environmental Protection (FDEP), is a vital effort to enhance coastal monitoring through advanced mapping technologies. The Woolpert team used airborne topographic-bathymetric (topo-bathy) lidar and vessel-based sonar to achieve coverage from the shore to the continental shelf edge. This dataset provides a detailed understanding of Florida’s seafloor, benefiting environmental management and the Blue Economy.

The topographic-bathymetric (topo-bathy) lidar mapping efforts focused on FSMI’s Region 3, covering over 27,000 square kilometers off the southern coast of Florida, including the Florida Keys, Dry Tortugas, and parts of the Southeast Gulf of Mexico. The lidar technology employed mapped depths up to 50 meters.

Furthermore, the Woolpert team supported the FSMI with vessel-based multibeam sonar surveys to achieve comprehensive seafloor mapping by filling gaps in the topo-bathy coverage or extending coverage deeper than 50 meters. The sonar work covered nearly 18,000 square kilometers in areas within Regions 1 (Northeast FL), 5 (Big Bend), and 6 (Panhandle). This dual lidar/sonar approach ensured that the FSMI achieved a complete bathymetric understanding of Florida’s territorial waters, enhancing the accuracy and utility of the data for various applications such as habitat mapping, navigation safety, and resource management.

Karen Hart, Woolpert, Inc.

Dave Neff, Woolpert, Inc.

11:45 AM – 12:00 PM – Combining UAS Topobathy Lidar With Traditional Hydrographic Survey Techniques To Safely Map Shallow Coastal and Inland Water Bodies

Today’s technology allows those in the surveying and mapping profession to address complex projects using different methods of collection which can be fused together, providing a detailed picture for all stakeholders. This presentation will discuss how UAS topobathy lidar was used to support hydrographic surveying of shallow waterways for a numerical modeling effort. We will discuss how the project was planned, acquired, processed, and all data validated and merged to create the final deliverables.

This approach enabled the field staff to efficiently collect a large area being studied while minimizing risk exposure to unknown hazards in the water.

Ravi Soneja, McKim & Creed

12:00 PM – 12:15 PM – Integrated Analysis of USGS 3DEP Inland Bathymetric Airborne Lidar Campaigns

USGS performed many inland bathymetric airborne lidar in the last decade. The airborne lidar data collection campaigns were performed at Kootenai river, Chehalis river, McKenzie river, Niobrara river, Alleghany river, and Potomac river. The water quality ranges from turbid shallow water with lots of suspended solids to the clean deep water. The bathymetric lidar systems used are Riegl VQ-880G, Leica Chiroptera, Leica HawkEye, and CZMIL Nova. The beam divergence ranges from 0.5 mrad for a higher point density system for shallow water to 5 mrad for a lower point density system for deep water. Laser pulse energy ranges from 0.02 mJ for shallow water system to 3 mJ for deep water system. The scanner types are either circular or elliptical. All bathymetric lidar systems uses 532 nm wavelength laser.  To increase the depth coverage, the airborne campaign was performed mostly in the dry season. Thus, most of the surveyed river were very shallow (less than a meter), and lesser area of shallow water (less than 5 meters), and small area of deep water. The depth coverage was analyzed using the las point classes provided by the data provider. The classes used are 40 (river bottom), 41(physical water surface), 42(synthetic water surface), 2(ground). Using the combination of these classes, it is possible to identify valid bathymetric lidar coverage and depth penetration. The validation of bathymetric lidar was performed using waded GNSS ground check points (GCPs) and Teledyne Z-boat single beam sonar GCPs. Z-boat data accuracy was also calibrated before using them as a reference for airborne bathymetric lidar accuracy. Also performed is the topo lidar accuracy using full 3D accuracy concept. Various 3D geometric features like multi-plane intercept, two-line crossing, plane to line crossing, and amorphous objects methods are used. In summary, we present the performance of bathymetric lidar performances over many rivers of varying optical properties using several different bathymetric lidar systems of varying specifications.

Minsu Kim, KBR / USGS

12:15 PM – 12:30 PM – Fusion of Drone and Sonar Data for Comprehensive Bathymetric and Topographic Survey of Water Bodies: A Case Study of Kirandich Dam in Kabarnet, Baringo County, Kenya

This study suggests a novel combination of drone-based aerial photogrammetry and sonar-based bathymetry for creating comprehensive topography and bathymetric maps of inland water bodies. The Kirandich Dam in Kabarnet, Baringo County, has been chosen as the study location. 

The goal of this study is to look into the success and precision of combining data from Unmanned Aerial Vehicles (UAVs) with single-beam or multi-beam sonar systems when surveying reservoirs and water bodies. The technique seeks to overcome the constraints of using either technology alone by merging aerial and underwater datasets for comprehensive 3D modelling and mapping.

Methodology included UAV photogrammetric surveys to produce high-resolution orthomosaics and Digital Surface Models (DSMs) of the surrounding terrain, as well as sonar equipment to capture depth profiles and underwater topography. An integrated elevation model was generated by processing and fusing the two datasets using GIS and remote sensing techniques. 

The goal was to create a more full and accurate depiction of the dam region, both above and below water, that may be utilized for water resource planning, sedimentation research, dam safety monitoring, and environmental management.

This work emphasizes the need of adopting modern geospatial technologies to improve the quality and comprehensiveness[A4] of inland water surveys, as well as contributing to the emerging subject of smart hydrographic mapping.

Anne Osio, The Technical University of Kenya (TU-K)