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