Latest Developments in Satellite Derived Bathymetry: Technology, Use Cases and Tools

Smart monitoring, planning and decision making for projects in the coastal and nearshore regions requires spatial and temporal understanding on the environmental parameters. Very often time and budget constraints preclude a comprehensive physical and environmental survey data collection exercise. Bathymetry, for example, is typically valid for one timestamp (during the period of data collection), one-dimensional (e.g. single beam surveys), and has sparse resolution in the shallow nearshore regions. In recent years, significant advances in satellite sensor technology and analysis have been developed to produce relevant information for coastal and nearshore monitoring applications at a fraction of both the time and cost of traditional methods. Aquatic Earth Observation techniques have been evolving since the 1970s. The recent advances on satellite sensor hardware and analytics have allowed the once crude methodology to be efficiently applied into practice-in particular very high-resolution satellite data availability and the sound understanding on the physical modelling of the light path from the surface/seafloor to the sensor. Applying over 20 years of continuous research and development, EOMAP has advanced a unique physics-based procedure which allows mapping of shallow water bathymetry, water quality parameters, seafloor characteristics and topography in dense spatial grids. Uncertainties in Earth Observation products are subject to a number of environmental factors that need to be accounted for. At the core of the technology are state-of-the-art algorithms for extracting quantitative environmental information from the aquatic remote sensing signal. Mechanisms for quantifying uncertainties and flagging relative reliabilities are embedded in the algorithms, which include: (1) allowance for coupled atmospheric and in-water parameter retrievals, which includes a correction of the (terrestrial) adjacency effect, critical for the accurate remote sensing of any coastal or inland water body, (2) a physically accurate implementation of the bi-directional effect inside the water column, at the water surface and in the atmosphere, (3) accounting for the full range of reflecting, absorbing and scattering properties of the water body and the interfaces. Those procedures are included in EOMAP's Watcor-X physics-based Satellite-Derived Bathymetry (SDB) software. This paper provides an overview of SDB, demonstrates successful project applications, and describe tools that support coastal and nearshore monitoring projects through the use of the software in the Pacific, Caribbean Sea and Arabian waters. We showcase the capability to monitor spatial seabed changes in highly dynamic environments, and demonstrate the latest technology that jointly incorporates the passive multispectral satellite imagery with complementary active Satellite-Lidar bathymetric data technology using NASA's ICESAT-2 Advanced Topographic Laser Altimeter System (ATLAS) sensor.