## [Mapping the World's Inland Surface Waters: An Upgrade to the Global Lakes and Wetlands Database (GLWD v2)](/resource/mapping-worlds-inland-surface-waters-upgrade-global-lakes-and-wetlands-database-glwd-v2) Organization [McGill University](/organization/mcgill-university) [Pacific Northwest National Laboratory](/organization/pacific-northwest-national-laboratory) [KU Leuven](/organization/ku-leuven) [Laboratory for the Study of Radiation and Matter in Astrophysics and Atmospheres (LERMA)](/organization/laboratory-study-radiation-and-matter-astrophysics-and-atmospheres-lerma) [Virginia Polytechnic Institute and State University](/organization/virginia-polytechnic-institute-and-state-university) [University Paris-Saclay](/organization/university-paris-saclay) [Commonwealth Scientific and Industrial Research Organization (CSIRO)](/organization/commonwealth-scientific-and-industrial-research-organization-csiro) [Charles Sturt University](/organization/charles-sturt-university) [University of New South Whales Sydney (UNSW)](/organization/university-new-south-whales-sydney-unsw) [Stockholm University](/organization/stockholm-university) [Wetlands International](/organization/wetlands-international) [Stanford University](/organization/stanford-university) [Chinese Academy of Sciences](/organization/chinese-academy-sciences) [Cornell University](/organization/cornell-university) [University of Alberta (UofA)](/organization/university-alberta-uofa) [The University of North Carolina at Chapel Hill](/organization/university-north-carolina-chapel-hill) [European Commission Joint Research Centre](/organization/european-commission-joint-research-centre) [National Aeronautics and Space Administration (NASA)](/organization/national-aeronautics-and-space-administration-nasa) [University of Illinois](/organization/university-illinois) [Kansas State University](/organization/kansas-state-university) [University of Cambridge](/organization/university-cambridge) [University of Tokyo](/organization/university-tokyo) [World Wildlife Fund](/organization/world-wildlife-fund) Resource Type [Peer reviewed article](/taxonomy/term/37) Author(s) Bernhard Lehner Mira Anand Etienne Fluet-Chouinard Florence Tan Filipe Aires George Allen Philippe Bousquet Josep Canadell Nick Davidson Meng Ding Max Finlayson Thomas Gumbricht Lammert Hilarides Gustaf Hugelius Robert Jackson Maartje Korver Liangyun Liu Peter McIntyre Szabolcs Nagy David Olefeldt Tamlin Pavelsky Jean-Francois Pekel Benjamin Poulter Catherine Prigent Jida Wang Thomas Worthington Dai Yamazaki Xiao Zhang Michele Thieme Original Authors Bernhard Lehner Mira Anand Etienne Fluet-Chouinard Florence Tan Filipe Aires George Allen Philippe Bousquet Josep Canadell Nick Davidson Meng Ding Max Finlayson Thomas Gumbricht Lammert Hilarides Gustaf Hugelius Robert Jackson Maartje Korver Liangyun Liu Peter McIntyre Szabolcs Nagy David Olefeldt Tamlin Pavelsky Jean-Francois Pekel Benjamin Poulter Catherine Prigent Jida Wang Thomas Worthington Dai Yamazaki Xiao Zhang Michele Thieme Contacts [Bernhard Lehner](/contact/bernhard-lehner) Resource Date: 2025 In recognition of the importance of inland waters, numerous datasets mapping their extents, types, or changes have been created using sources ranging from historical wetland maps to real-time satellite remote sensing. However, differences in definitions and methods have led to spatial and typological inconsistencies among individual data sources, confounding their complementary use and integration. The Global Lakes and Wetlands Database (GLWD), published in 2004, with its globally seamless depiction of 12 major vegetated and non-vegetated wetland classes at 1 km grid cell resolution, has emerged over the last few decades as a foundadtional reference map that has advanced research and conservation planning addressing freshwater biodiversity, ecosystem services, greenhouse gas emissions, land surface processes, hydrology, and human health. Here, we present a new iteration of this map, termed GLWD version 2, generated by harmonizing the latest ground- and satellite-based data products into one single database. Following the same design principle as its predecessor, GLWD v2 aims to avoid double counting of overlapping surface water features while differentiating between natural and non-natural lakes, rivers of multiple sizes, and several other wetland types. The classification of GLWD v2 incorporates information on seasonality (i.e., permanent vs. intermittent vs. ephemeral); inundation vs. saturation (i.e., flooding vs. waterlogged soils), vegetation cover (e.g., forested swamps vs. non-forested marshes), salinity (e.g., salt pans), natural vs. non-natural origins (e.g., rice paddies), and stratification of landscape position and water source (e.g., riverine, lacustrine, palustrine, coastal/marine). GLWD v2 represents 33 wetland classes and – including all intermittent classes – depicts a maximum of 18.2 × 106 km2 of wetlands (13.4 % of the global land area excluding Antarctica). The spatial extent of each class is provided as the fractional coverage within each grid cell at a resolution of 15 arcsec (approximately 500 m at the Equator), with cell fractions derived from input data at resolutions as small as 10 m. The upgraded GLWD v2 offers an improved representation of inland surface water extents and their classification for contemporary conditions (1984–2020). Despite being a static map, it includes classes that denote intrinsic temporal dynamics. GLWD v2 is designed to facilitate large-scale hydrological, ecological, biogeochemical, and conservation applications, aiming to support the study and protection of wetland ecosystems around the world. The GLWD v2 database is available at https://doi.org/10.6084/m9.figshare.28519994 (Lehner et al., 2025).