MnemonicUnits Terrain Type
LAND Percent Dry land
FLAK Percent Perennial freshwater lakes
SWMP Percent Swamp, marsh and other wetlands
SLAK Percent Salt lakes
OCEA Percent Salt water of the ocean
ILAK Percent Intermittent water bodies
GLAC Percent Glacier ice
DUNE Percent Sand dunes
SMRS Percent Saltmarsh
SFLT Percent Salt flats
DSRF Percent Land+Swamp+Sand dunes+Saltmarsh
SLTW Percent Saltwater, marine or terrestrial
FRIV Counts Perennial rivers
IRIV Counts Intermittent rivers
RNOFmm/a Surface runoff of water
RNER Percent Estimated rms error of RNOF
RICEmm/a Runoff of ice
MS05 A 5-percent land mask
BAS1 Major drainage basins
BAS2 Smaller drainage basins
CRYO Main features of the cryosphere
GGHYDRO is a global hydrographic dataset with a resolution of 1° in longitude and latitude. It consists of 21 fields of data. Two of these, GLAC and CRYO, are of direct glaciological relevance. The fields, listed in the table, include estimates of the percentage extent of hydrologically or climatologically interesting terrain types; stream frequency counts; estimates of runoff; and digital maps of the major continental drainage basins and of the cryosphere.

GGHYDRO was compiled in the mid-1980s as a tool for helping to describe the world's land surfaces to general circulation climate models. While more accurate or more highly resolved descriptions of the contents of some of the fields are now available, GGHYDRO retains its original advantages of moderate size, internal consistency and useful content. It has been corrected periodically as errors have been detected. To view maps of the GGHYDRO fields, click GGHYDRO maps .

GGHYDRO field CRYO - Main features of the cryosphere
Shades of brown: local extent of permafrost (absent, restricted, common, ubiquitous). Shades of magenta: local extent of sea ice (seasonal, permanent). Blue: ice sheets. Cyan: ice shelves.
GGHYDRO Release 2.3.1 is now available. It differs only in format, not content, from Release 2.3 of January 2003. Release 2.3.1 is organized into
  • 21 data files (see table above);
  • one supplementary file, GGHBAS2.LST, which lists the codes occurring in BAS2 and provides additional information for interpreting the codes;
  • GGHREAD.ME, a file explaining the organization of the dataset and providing a revision log;
  • and GGHREAD.F90, containing a sample Fortran read procedure.
GGHYDRO may be used freely, provided that it not be sold for profit and that it be duly acknowledged in any published work.

More details about the content and format of GGHYDRO are provided by Cogley (2003).

Cogley (1989) explains the derivation of GGHYDRO fields RNOF, RNER and RICE.

Cogley, J.G., 2003, GGHYDRO - Global Hydrographic Data, Release 2.3.1, Trent Technical Note 2003-1, Department of Geography, Trent University, Peterborough, Ontario, Canada. Revised January 2007.

Cogley, J.G., 1998, GGHYDRO - Global Hydrographic Data, Release 2.2, Trent Climate Note 98-1, Department of Geography, Trent University, Peterborough, Ontario, Canada.

Cogley, J.G., 1989, Runoff from the World's Landmasses: Amounts and Uncertainties at 2-degree Resolution, Trent Climate Note 89-3, Department of Geography, Trent University, Peterborough, Ontario, Canada. 8p.

Some Recent Users of GGHYDRO
Arora, V.K., F.H.S. Chiew and R.B. Grayson, 1999, A river flow routing scheme for general circulation models, Journal of Geophysical Research, 104, 14347-14357.

Bonan, B.G., 1995, Sensitivity of a GCM simulation to inclusion of inland water surfaces, Journal of Climate, 8, 2691-2704.

Braithwaite, R.J., 2002, Glacier mass balance: the first 50 years of international monitoring, Progress in Physical Geography, 26(1), 76-95.

Coe, M.T., 2000, Modeling terrestrial hydrological systems at the continental scale: testing the accuracy of an atmospheric GCM, Journal of Climate, 13, 686-704.

Coe, M.T., 1998, A linked global model of terrestrial hydrologic processes: simulation of modern lakes, rivers and wetlands, Journal of Geophysical Research, 103, 8885-8899.

Coe, M.T., 1997, Simulating continental surface waters: an application to Holocene North Africa, Journal of Climate, 10, 1680-1689.

Levis, S., J.A. Foley and D. Pollard, 2000, Large-scale vegetation feedbacks on a doubled CO2 climate, Journal of Climate, 13, 1313-1325.

Levis, S., M.T. Coe and J.A. Foley, 1996, Hydrologic budget of a land surface model: a global application, Journal of Geophysical Research, 101, 16921-16930.

Prigent, C., E. Matthews, F. Aires and W.B. Rossow, 2001, Remote sensing of global wetland dynamics with multiple satellite data sets, Geophysical Research Letters, 28(24), 4631-4634.

Raper, S.C.B., and R.J. Braithwaite, 2005, The potential for sea level rise: new estimates from glacier and ice cap area and volume distributions, Geophysical Research Letters, 32, L05502, doi:10.1029/2004GL021981.