1950 - 2023 NOAA Seamless Topobathy DEM (Compiled 2023): Kachemak, Point Hope, Teller, AK

NOAA Seamless Topobathy Digital Elevation Model Pilot Incorporating Satellite-Derived Bathymetry - Kachemak, Teller, Point Hope, Alaska, project number 1305M223FNCNP0283DPR. Seamless topographic-bathymetry models were produced for three AOIs along the Alaskan coast, integrating multiple source datasets including bathymetric lidar, topographic lidar, multibeam and singlebeam echosounder, IFSAR, and satellite-derived bathymetry (SDB). Satellite-derived bathymetry was produced using empirical and physics-based radiative transfer models, derived from Maxar and Planet Labs mutlispectral imagery. All data sources were adjusted from MLLW to NAVD88 before integrating to a weighted grid, with weights assigned based on quality and data currency. The weighted grid was then interpolated utilizing Generic Mapping Tools (GMT) surface module, leveraging a spline-in-tension interpolation. DEMs were delivered at 2m resolution. Each DEM delivery includes ancillary files including an in situ source map raster, a known issue polygon feature class, source imagery utilized for SDB production, the individual SDB rasters integrated with the topographic-bathymetry model.

Kachemak AOI covers approximately 1012 km2

Point Hope AOI covers approximately 2329 km2

Teller AOI covers approximately 1160 km2

Procured for NOAA Office for Coastal Management, the primary objective of this project was to fill bathymetric data gaps according to the Alaska Mapping Executive Committee (AMEC). This objective was to be achieved through acquiring new Satellite Derived Bathymetric (SDB) data in the assigned areas of interest (AOI), with the goal of expanding bathymetric data coverage beyond the current coverage from sonar and LiDAR datasets. Additionally, to create a seamless topographic-bathymetric digital elevation model (DEM) using existing topographic-bathymetric LiDAR, sonar bathymetry, terrestrial LiDAR, Interferometric Synthetic Aperture Radar (iFSAR), and TCarta SDB data. This was a pilot project to demonstrate how SDB can be used to fill in data gaps in hard to map areas due to accessibility, prohibitive cost associated with ship-based and LiDAR surveys, narrow windows of opportunities to perform survey work due to environmental and harsh weather conditions, and potential risks to operators surveying in these remote and unsurveyed areas.

Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the Office for Coastal Management or its partners.

Data is available online for bulk and custom downloads.

None

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations.

Python 3.10; Esri ArcGIS Pro 3.1; TCarta Trident Tools; Pure File Magic v6.4.0.43; Generic Mapping Tools 6.0

To assess the vertical accuracy of the DEMs, a set of 3,000 randomly sampled points from each of the AOI's non-SDB bathymetry sources were collected. The elevation of each point was compared to the coincident DEM elevation, deriving absolute error, and absolute percent error. From these point statistics, an overall assessment of vertical accuracy was established.

Kachemak - 1.17 m RMSE

Teller - 0.51 m RMSE

Point Hope - 0.12 m RMSE

Complete

Imbricate source insitu sources were deconflicted where possible utilizing spatial autocorrelation thresholding. All Satellite-Derived Bathymetry (SDB) including in the DEM was processed in a 3D-point cloud environment to remove spurious returns and outliers.

Data is backed up to cloud storage.

TCarta/Axim created seamless topographic-bathymetry models for three AOIs along the Alaskan coast, integrating multiple source datasets including bathymetric lidar, topographic lidar, multibeam and singlebeam echosounder, IFSAR, and satellite-derived bathymetry (SDB) for the NOAA Office for Coastal Management (OCM). OCM processed the DEMs to make them available for custom and bulk download from the NOAA Digital Coast Data Access Viewer (DAV).