Download Bathymetry

GEBCO 2019

The GEBCO 2019 dataset is now placed in the "public domain", but please read the terms of use carefully.

Resultion is 15-arc now, which is about 460 m at the equator at sea level. Therefore the datasets are not suitable for visualisation at large scales.

According to Tobler´s rule: Map Scale = Raster resolution (in meters) * 2 * 1000 = 1:920.000 (Zoom Level 9)

Download GEBCO 2019 derived raster classification

Download GEBCO 2019 derived contour lines

Attributation: Derived product from the GEBCO 2019 Grid, made with NaturalEarth
by OpenDEM

Processing Raster Clasification

The original GEBCO dataset was reduced to integer values with gdal_translate -ot Int16 and then classified with GRASS GIS r.reclas. See the parameters at the bottom of this page. The dataset was clipped with gdalwarp -cutline to the Ocean dataset from Natural Earth.

Processing Contour Lines

The original GEBCO dataset was reduced to integer values with gdal_translate -ot Int16. Contours were derived with gdal_contour. The dataset was clipped with ogr2ogr clipdst to the Ocean dataset from Natural Earth. For performance reasons the countours were split with the QGIS SAGA tool Split line with lines in a 10 degree fishnet.

Be aware that the ogr2ogr clipping is a litte tricky (see that post). Successful was this command:

ogr2ogr -nlt LINESTRING -skipfailures -spat -90.0 -45.0 -45.0 -90.0 -clipsrc -90.0 -45.0 -45.0 -90.0 output.shp input.shp

You can see the visualisation of the datasets here. There is also a WMS available:

https://www.opendem.info/geoserver/opendem/wms

Layers: opendem:gebco_2019_contours & opendem:gebco_2019

The first Class -1 to - 25 metres is there not rendered, because there were to much intersections with the applied Natural Earth countries. When a raster is clipped with gdalwarp -cutline the cell is clipped when the center point of the cell is within the polygon. Therefore still intersections with the land tiles can occur.

GEBCO 2014

The data was derived for OpenSeaMap from the GEBCO_2014 Grid, version 20141103 www.gebco.net, and has use limitations:

"Use of the printed map and/or digital imagery for scientific research, environmental conservation, education or other non-commercial purposes is authorised without the prior permission of the data set originators, providing the source material is properly credited."

Please credit the source properly.

The resolution of the GEBCO 2014 dataset is 30-arc seconds.

Strait of Gibraltar

Fig. 1: Strait of Gibraltar with the downloadable bathymetry data. OSM tiles as background.

Bathymetry Polygons Download

Bathymetry Contours Download

SLD Polygons Download

A bicubic interpolation of the gebco data was done by the factor 3.

The data was clipped with the OSM landtiles to avoid overlapping.

The data was classified on base of the depth values:

-1 thru -24.99 = 1
-25 thru -49.99 = 2
-50 thru -99.99 = 3
-100 thru -249.99 = 4
-250 thru -499.99 = 5
-500 thru -749.99 = 6
-750 thru -999.99 = 7
-1000 thru -1249.99 = 8
-1250 thru -1499.99 = 9
-1500 thru -1749.99 = 10
-1750 thru -1999.99 = 11
-2000 thru -2499.99 = 12
-2500 thru -2999.99 = 13
-3000 thru -3499.99 = 14
-3500 thru -3999.99 = 15
-4000 thru -4499.99 = 16
-4500 thru -4999.99 = 17
-5000 thru -5499.99 = 18
-5500 thru -5999.99 = 19
-6000 thru -6499.99 = 20
-6500 thru -6999.99 = 21
-7000 thru -7499.99 = 22
-7500 thru -7999.99 = 23
-8000 thru -8499.99 = 24
-8500 thru -8999.99 = 25
-9000 thru -9499.99 = 26
-9500 thru -12000 = 27

Polygons were computed and splitted for a better performance.

Contours were derived.

 

 

 

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