Exploration of Satellite-Based Bathymetry Analysis - Investigating advanced LiDAR techniques to boost coastal depth mapping by satellites
In the realm of hydrography, recent advancements in satellite-derived bathymetry (SDB) have significantly enhanced the mapping of coastal and shallow waters, supporting nautical charting and safety of navigation applications.
One of the key developments is the improved depth estimation accuracy. By integrating satellite imagery, such as Sentinel-2, with airborne LiDAR and other data sources, the accuracy and robustness of SDB measurements have increased. This improvement enables finer depth resolution suitable for many coastal mapping needs [3][4].
Satellites also analyse how light penetrates shallow coastal waters to estimate seabed depths across large areas quickly. While this method is less precise than acoustic sonar, it provides valuable first approximations in regions lacking direct surveys. Recent efforts have achieved spatial grids as fine as 10 meters resolution down to 20–30 meters water depth, adequate for many safety-related applications [2].
Artificial intelligence and machine learning are increasingly applied to enhance data processing and interpretation. Advances in autonomous platforms, drones, and underwater sensors complement satellite data, providing multi-dimensional views of underwater terrain [1][5].
Capacity building and collaborative models are also essential. Training programs and partnerships with private firms help coastal nations generate and share their own SDB data, fostering regional hydrographic capabilities and environmental stewardship [2].
Crowdsourced data contributions from commercial ships, fishing vessels, and yachts also enrich the hydrospatial understanding along heavily trafficked routes and improve nautical charts [2].
However, several challenges persist. Optical satellite methods generally work best in clear, shallow waters (up to ~30 meters depth). Turbidity, water color, and bottom type can reduce data quality, restricting use for deep or highly complex navigational areas [2][3].
SDB often needs extensive local validation via sonar or in situ measurements, which can be costly and logistically challenging [4].
Technical, political, and economic factors limit global coverage and equitable access to SDB technologies, especially in developing regions. Efforts like the Seabed 2030 project aim to address these disparities [1].
The conservative nature of maritime safety standards requires rigorous verification before SDB can fully replace traditional acoustic surveys in critical navigation charts, limiting immediate operational use [1][2].
In summary, while NASA's ICESat-2 and other spaceborne sensors have propelled SDB capabilities forward, improving efficiency and coverage for nautical charting and marine safety, ongoing challenges in accuracy, depth limitations, ground truthing, and policy integration remain key hurdles for broader operational adoption. Continued technological innovation, international collaboration, and data democratization will be crucial for maximizing SDB's contribution to safe navigation [1][2][3].
References:
[1] The paper "Satellite Derived Bathymetry (SDB) and Safety of Navigation" was published in The International Hydrographic Review in 2017. [2] The Satellite Computed Bathymetry Assessment (SCuBA) project team at NGA has developed a process to prepare satellite lidar data for use in nautical charting and safety of navigation. [3] The paper "Geographically Adaptive Inversion Model for Improving Bathymetric Retrieval From Satellite Multispectral Imagery" was published in IEEE Transactions on Geoscience and Remote Sensing in 2014. [4] The 2018-2019 NOAA NGS Topobathy Lidar Hurricane Irma data for Miami to Marquesas Keys, FL can be found at https://www.fisheries.noaa. gov/inport/item/63017 (accessed 10 May 2023). [5] The Florida Keys have been used to test SCuBA derived depths against traditional airborne bathymetric lidar survey, and the results revealed substantially similar depths with a mean vertical error less than 0.09 m and within 3.6% of the depth. [6] Fusing space-based lidar with other SDB techniques using multispectral imagery has been shown to add value to both types of data for hydrographic purposes. [7] Continued development of advanced algorithms to improve spaceborne lidar bathymetry is an important step in completely mapping the Earth's oceans, and ensuring nautical chart products serve their purpose and keep mariners appraised of hazards at sea. [8] The paper "Satellite Computed Bathymetry Assessment-SCuBA" was presented at the AGU Fall Meeting in 2020. [9] The paper "A Synoptic Review on Deriving Bathymetry Information Using Remote Sensing Technologies: Models, Methods and Comparisons" was published in Advances in Remote Sensing in 2015. [10] The SCuBA project has developed an operational process that prepares ATL03 Global Geolocated Photon Data products available from NASA to optically correct and classify shallow ocean photon returns into accurate depths required for hydrographic purposes. [11] Hydrographic applications of SDB have leveraged complex spatial models, machine learning techniques, and methods that use radiative transfer models or empirically derived relationships between water depth and radiance to estimate water depths. [12] The Advanced Topographic Laser Altimeter System (ATLAS) onboard the US National Aeronautics and Space Administration (NASA) Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) has been utilized to extract coastal bathymetry via its green wavelength laser. [13] The paper "Recent changes of global ocean transparency observed by SeaWiFS" was published in Continental Shelf Research in 2017. [14] Methods to produce satellite derived bathymetry (SDB) from space-based sensors have emerged in recent decades. [15] The paper "Improving Optical Bathymetry Estimation with Constrained Geographically Weighted Regression Using Object-Based Image Analysis" was written by S. Quan in 2021. [16] The paper "Validation of ICESat-2 ATLAS Bathymetry and Analysis of ATLAS's Bathymetric Mapping Performance" was published in Remote Sensing in 2019. [17] The paper "Remote sensing of water depths in shallow waters via artificial neural networks" was published in Estuarine, Coastal and Shelf Science in 2010. [18] The paper "Thirty years of satellite derived bathymetry - The charting tool that hydrographers can no longer ignore" was published in The International Hydrographic Review in 2020. [19] The paper "ICESat-2 Elevation Retrievals in Support of Satellite-Derived Bathymetry for Global Science Applications" was published in Geophysical Research Letters in 2021. [20] The Seabed2030 project is accessible at www.seabed2030.org (accessed 6 Jan. 2022). [21] The IHO Data Centre for Digital Bathymetry (DCDB) is accessible at https://www.ngdc.noaa.gov/iho/ (accessed 13 Mar. 2023). [22] The Algorithm Theoretical Basis Document (ATBD) for Global Geolocated Photons can be found at https://icesat-2.gsfc.nasa.gov/sites/default/files/page_files/ICESat2_ATL03_ATBD_r005.pdf (accessed 22 Sep. 2023). [23] The Technical Specs for ICESat-2 can be found at https://icesat-2.gsfc.nasa.gov/science/specs (accessed 13 Mar. 2023). [24] The paper "Geological origin of the volcanic islands of the Caroline Group in the Federated States of Micronesia, Western Pacific" was published in South Pacific Studies in 2013.
- Advances in technology, such as artificial intelligence and machine learning, are being used to enhance data processing and interpretation for hydrographic survey, improving nautical charting and ensuring the safety of navigation.
- Science, including environmental-science and climate-change research, can benefit from renewable-energy projects through the collection and analysis of data-and-cloud-computing, which is crucial for hydrographic survey and nautical charting.
- The industry, collaborating with private firms and academic institutions, is playing a vital role in strengthening regional hydrographic capabilities, fostering environmental stewardship, and expanding access to the science of hydrographic survey.
- The finance sector could potentially invest in infrastructure and research initiatives to support the advancement of hydrographic survey, improving the safety of navigation and contributing to the understanding of the marine environment.
- Climate-change and its impact on shallow water conditions, such as turbidity, water color, and bottom type, pose challenges to the accuracy of satellite-derived bathymetry, hindering its use in deep or highly complex navigational areas.
- The development and implementation of technology like satellite-derived bathymetry can contribute significantly to the energy sector, providing accurate data for navigation, supporting renewable offshore energy projects, and ensuring the safe and efficient use of marine resources.
