Bathymetry refers to the measurement of the depth of water in various water bodies such as oceans, seas, and lakes. Bathymetric maps are designed to show the underwater topography, including depth contours and bottom features such as ridges, trenches, and channels.
What are bathymetric maps?
Bathymetric mapping is essential in maritime industries and research activities to understand the seafloor terrain, identify hazards, and locate resources. Bathymetric mapping has become more efficient, accurate, and user-friendly by geospatial tools and methods. These maps are essential for marine navigation and exploration, ecological studies, and ocean research.
ArcGIS Pro is a geographic information system (GIS) software used by professionals in diverse fields such as environmental management, urban and coastal planning, and resource management. It is a comprehensive software package that allows the user to create, edit, manage, and analyze geospatial data by the use of geoprocessing tools.
As a result, ArcGIS Pro is an excellent tool for the creation of bathymetric maps. ArcGIS Pro software allows bathymetric engineers and researchers to handle large and complex datasets, analyze them, and create high-quality maps that are essential for maritime operations and scientific research.
General Bathymetric Chart of the Oceans
The GEBCO dataset (General Bathymetric Chart of the Oceans) is a comprehensive global dataset that provides information about the depth and shape of the world’s oceans and seas. It is a collaborative effort between the International Hydrographic Organization (IHO) and the Intergovernmental Ocean Commission (IOC).
The dataset is comprised of a digital bathymetric model of the world’s oceans, covering areas from the coastal zone down to the deepest parts of the seabed. It includes data from over 230 million depth soundings collected from a variety of sources including ships, satellites, and other oceanographic instruments.
The GEBCO dataset is widely used in a variety of applications, including navigation, marine resource management, scientific research, and climate modeling. The dataset is regularly updated and improved as new data becomes available, helping to ensure that it remains one of the most comprehensive and accurate sources of oceanic bathymetric information in the world.
Learn how to create a bathymetry map using GEBCO data in ArcGIS Pro
For this tutorial a step-by-step approach on downloading bathymetric data from the GEBCO website, importing and mapping out the data into ArcGIS Pro, and creating contours from the data are given. Figure 1 also provides a summary of the geospatial tools and methods employed in downloading bathymetric data from GEBCO and mapping them out in ArcGIS Pro with contours.
How to find bathymetric datasets from GEBCO
- Open the General Bathymetric Chart of the Oceans (GEBCO)’s website (GEBCO – The General Bathymetric Chart of the Oceans).
- Select “Read more” of gridded bathymetric data.
- Scroll down to the panel of “download data for user-defined areas” and click the application window.
- Set “Select grid version” to GEBCO 2022.
- Hold down the Ctrl key and use the mouse pointer to define the area of interest.
- Set “Select formats” to Geotiff.
- Click “Add to Cart.”
- Click “View basket.”
- Click “Download your data.”
Importing bathymetric data into ArcGIS Pro
To map out the bathymetric data into ArcGIS Pro, ensure that the retrieved file is extracted into a new folder and follow the steps outlined:
- Open and create a new project in ArcGIS Pro.
- From the Map tab, select “Add data.”
- Toggle to the location of the downloaded GEBCO data and click Ok.
- If the GEBCO file (bathymetric data) is larger than the Area of Interest (AOI), use the “extract by mask” tool to clip to desired boundary using the outlined steps;
- Type and search “Extract by mask” from the search bar of the geoprocessing toolbox.
- Set input raster to imported bathymetric file.
- Set feature mask to the boundary of AOI.
- Set output raster to the name and location of the output file.
- Click Run.
Creating contours from bathymetric data in ArcGIS Pro
Before creating contours from the bathymetric data, follow the steps outlined to check the data’s coordinate system:
- Right-click on the imported dataset from the “table of contents.”
- Select “properties.”
- Click “source.”
- Expand the spatial reference tab to examine the coordinate system of the data.
For this tutorial, the coordinate system of the bathymetric data will be converted from WGS84 to WGS_1984_UTM_Zone_32N. To do this:
- Type and search “project raster” from the search bar of the geoprocessing toolbox.
- Set input raster to the bathymetric data.
- Set output raster to the name and location of the resulting raster.
- Set output coordinate system to “WGS_1984_UTM_Zone_32N.”
- Click Run.
Use the steps outlined above to examine the coordinate system of the resulting bathymetry raster file.
To enhance the visualization output of the projected bathymetry raster file, use the steps outlined below;
- Right-click on the projected raster file from the table of contents.
- Select symbology.
- From the primary symbology panel, select classify.
- Set number of classes to 5.
- Set color scheme to desired visualization output.
To create contours from the bathymetric data:
- Type and search contour from the search box of the geoprocessing toolbox.
- Set input raster to the projected file.
- Set output feature class to the location and name of the resulting contours.
- Set contour interval to 200.
- Click Run.
The final look showing ocean water depth overlaid with contours: