GSHHG

A Global Self-consistent, Hierarchical, High-resolution Geography Database

Version 2.2.2 Released January 1, 2013

GSHHG is developed and maintained by

Paul Wessel, SOEST, University of Hawai'i, Honolulu, HI.
Walter H. F. Smith, NOAA Geosciences Lab, National Ocean Service, Silver Spring, MD.

We present a high-resolution geography data set amalgamated from two data bases in the public domain: World Vector Shorelines (WVS) and CIA World Data Bank II (WDBII). The former is our basis for shorelines while the latter is the basis for lakes, although there are instances where differences in coastline representations necessitated adding WDBII islands to GSHHG. The WDBII source also provides all political borders and rivers. GSHHG data have undergone extensive processing and should be free of internal inconsistencies such as erratic points and crossing segments. The shorelines are constructed entirely from hierarchically arranged closed polygons. A modified version of GSHHG is used by GMT, the Generic Mapping Tools. As of version 2.2.2, GSHHG is released under the GNU Lesser General Public License.
The shoreline polygon data can be used to simplify data searches and data selections, to study the statistical characteristics of shorelines and land-masses, or for custom applications requiring basic geography data. For convenience, the shoreline polygons and rivers/borders line data sets are distributed in two file formats:

  1. ESRI shapefiles. This format is probably the most useful for users of GSHHG. Note that due to limitations of most (all?) GIS software and Google Earth, a handful of polygons straddling the Dateline (chief among them the Antarctic polar cap polygon) have been split into east and west components.
  2. Native binary files. No polygon dateline-splitting has occurred. Software to read these files are distributed as part of the gshhg supplement to GMT. Developers can use the descriptions of the gshhg format to deal with these data in their own programs.

Notes:

  1. GMT uses a special netCDF-formatted version of these data that have been tiled to improve efficiency of map making. Normally, this flavor of GSHHG is offered as an installation option when GMT is installed; however, you can also obtain it below. We discourage anyone from using the netCDF version for custom programming applications [due to complexity and lack of documentation, mostly].
  2. GSHHG used to be called GSHHS (Global Self-consistent, Hierarchical, High-resolution Shorelines) but since rivers and political boundaries were also included we changed it to GSHHG starting with version 2.2.1.
  3. The netCDF version of GSHHG used to be distributed as a part of GMT but as of GMT 4.5.9 the GSHHG is a separate package. This means when GMT is updated and there are no changes to GSHHG you do not need to reinstall GSHHG. Likewise, GMT 4 and GMT 5 installations can now share a single GSHHG installation.

The geography data come in five resolutions:
  1. full resolution: Original (full) data resolution.
  2. high resolution: About 80 % reduction in size and quality.
  3. intermediate resolution: Another ~80 % reduction.
  4. low resolution: Another ~80 % reduction.
  5. crude resolution: Another ~80 % reduction.
Unlike the shoreline polygons at all resolutions, the lower resolution rivers are not guaranteed not to cross.
Shorelines are furthermore organized into 4 hierarchical levels:
  1. L1: boundary between land and ocean.
  2. L2: boundary between lake and land.
  3. L3: boundary between island-in-lake and lake.
  4. L4: boundary between pond-in-island and island.

Published information about GSHHG

The processing and assembly of the shoreline data is described in

Wessel, P., and W. H. F. Smith, A Global Self-consistent, Hierarchical, High-resolution Shoreline Database, J. Geophys. Res., 101, 8741-8743, 1996 [PDF].

Availability of GSHHG data

The latest data files for version 2.2.2 were released on January 1, 2013; details on the changes are described in the README file. The data set can be accessed below as well as from the National Geophysical Data Center (NGDC), Boulder, Colorado. Note that the gshhg software is a GMT supplement so if you have installed GMT you already have the gshhg software. For GMT 4.5.9 or later, or GMT 5.*, you may download one of these files via ftp
  1. FTP: GSHHG coastlines, rivers, and borders for GMT in netCDF 4 format (gzipped tar archive).
  2. FTP: GSHHG coastlines, rivers, and borders for GMT in netCDF 3 format (bzipped tar archive) [for older netCDF-3-only installations].
or via HTTP
  1. HTTP: GSHHG coastlines, rivers, and borders for GMT in netCDF 4 format (gzipped tar archive).
  2. HTTP: GSHHG coastlines, rivers, and borders for GMT in netCDF 3 format (bzipped tar archive) [for older netCDF-3-only installations].
For ESRI shapefiles of shoreline polygons, rivers, and borders you can choose to get via ftp or http: For native binary files of shoreline polygons, rivers, and borders you may download via ftp or http: The latter requires GMT's gshhg supplement or your own custom programs to access the data. The native binary shoreline data can also be converted into a GRASS GIS database with v.in.gshhs, a GRASS add-on by Markus Metz.
A related product is a global netCDF grid with distances to the nearest GSHHG shoreline in cm. This is a 1x1 arc minute grid based on GSHHS version 1.3 and can be obtained here: dist_to_GSHHS_v1.3_1m.nc [Note: it is 890 Mb and is not yet updated to GSHHG 2.2.2].
Last update January 1, 2013 by Paul Wessel