The 1’ global wetlands, lakes and reservoirs map WELAREM1

Bernhard Lehner and Petra Döll

The global 1’ raster map of wetlands, lakes and reservoirs WELAREM1 was derived by combining various digital maps (ESRI, 1993 - wetlands, lakes and reservoirs; ESRI, 1992 - wetlands, lakes, reservoirs and rivers; WCMC, 1999 - lakes and wetlands; Vörösmarty et al., 1997 - reservoirs) and attribute data (ICOLD, 1998 - reservoirs; Birkett and Mason, 1995 - lakes and reservoirs). For the map generation approx. 300000 vectorized lakes and reservoirs were considered. Wetlands encompass also stretches of large rivers, as it is assumed that only a river with adjacent wetlands (floodplain) is wide enough to be drawn as a polygon on the 1:3 million map of ESRI (1992). In the generated data set, wetlands cover 6.6 % of the global land area (without Antarctica and Greenland), and lakes and reservoirs 2.1 %.

The map distinguishes "local" from "global" lakes and wetlands, the local open water bodies being those that are only supplied by the runoff generated within the cell and not by additional inflow from upstream cells.


  • Birkett, C.M., Mason, I.M. (1995): A new global lakes database for a remote sensing programme studying climatically sensitive large lakes. Journal of Great Lakes Research, 21(3), 307-318.
  • ESRI (1993): Digital Chart of the World 1:1 M.
  • ESRI (1992): ArcWorld 1:3 M Continental Coverage.
  • ICOLD (International Commission on Large Dams) (1998): Word Register of Dams (CD-Rom). Paris, France.
  • Vörösmarty, C.J., Sharma, K., Fekete, B., Copeland, A.H., Holden, J., Marble, J., Lough, J.A. (1997): The storage and aging of continental runoff in large reservoir systems of the world. Ambio, 26: 210-219.
  • WCMC (World Conservation Monitoring Centre) (1999):Wetlands Dataset, Cambridge, UK.

If you wish to obtain the data set, please contact Prof. Dr. Petra Döll.