Global Lakes and Wetlands Database (GLWD)

The Global Lakes and Wetlands Database(GLWD) has been created on the basis of existing maps, data and information, such as the Digital Chart of the World, World Conservation Monitoring Centre (WCMC) and others. It focuses in three coordinated levels on (1) large lakes and reservoirs, (2) smaller water bodies, and (3) wetlands.

Level 1 (GLWD-1) comprises the shoreline polygons of the 3067 largest lakes (area ≥ 50 km2) and 654 largest reservoirs (storage capacity ≥ 0.5 km3) worldwide, and includes extensive attribute data. Level 2 (GLWD-2) comprises the shoreline polygons of permanent open water bodies with a surface area ≥ 0.1 km2 excluding the water bodies contained in GLWD-1. The approx. 250,000 polygons of GLWD-2 are attributed as lakes, reservoirs and rivers. Level 3 (GLWD-3) comprises lakes, reservoirs, rivers and different wetland types in the form of a global raster map at 30 arc-second (about 1 km) resolution. The GLWD-3 dataset has 12 classes as follows: (1) Lake; (2) Reservoir; (3) River; (4) Freshwater Marsh, Floodplain; (5) Swamp Forest, Flooded Forest; (6) Coastal Wetland (incl. Mangrove, Estuary, Delta, Lagoon); (7) Pan, Brackish/Saline Wetland; (8) Bog, Fen, Mire (Peatland); (9) Intermittent Wetland/Lake; (10) 50-100% Wetland; (11) 25-50% Wetland; (12) 0-25% Wetland.

In a validation against documented data GLWD proved to represent a comprehensive database of global lakes ≥ 1 km2 and to provide a good representation of the maximum global wetland extent. For the purpose of land resource assessment and planning GLWD is best used at global or regional level. At national or sub-national levels the availability of national datasets on open waters and wetlands is to be checked first.