GLWD v2.0 — Global Lakes and Wetlands Database (2025)
Global raster maps of wetland classes (33 types spanning open water, lacustrine,
riverine, palustrine, ephemeral, peatland, and coastal wetlands) at ~500 m
resolution, plus per-pixel wetland area. From Lehner et al. (2025),
doi:10.5194/essd-17-2277-2025;
see also the HydroSHEDS GLWD product page.
Both hex layers are H3 resolution 8, one row per h8 cell, hive-partitioned by
h0, with parent indexes h7/h6/h5 for multi-scale joins. Re-hexed on the
antimeridian/polar-fixed pipeline (boettiger-lab/datasets #88/#92/#93,
data-workflows #186).
Dominant wetland class (glwd-hex)
Z is the mode (most frequent) class per cell — query it directly, no GROUP BY
needed:
Z is categorical (0 = Dryland, 1–33 = wetland types; see classification:classes
in the STAC). Do not sum or average it.
Wetland area (glwd-area-hex) — answers "how many acres of wetland in ?"
area_ha_x10 is the area-weighted wetland area per cell, in hectares × 10
(wetland ha = area_ha_x10 / 10). It is a complete H3 res-8 grid — area_ha_x10 = 0
where the cell has no wetland (the same full-grid shape as the carbon / ghs-pop sum
layers). An AOI join + SUM gives that AOI's wetland area directly:
SUM(area_ha_x10) is directly valid — raster-derived, one row per cell, no
per-feature duplication, no dedup. It is mass-conserving against the source COG.
Displaying the COGs (MapLibre GL JS via TiTiler)
Wetland classes (GLWD v2.0)
Code
Class
Code
Class
0
Dryland (non-wetland)
17
Palustrine, reg. flooded, non-forested
1
Freshwater lake
18
Palustrine, seas. saturated, forested
2
Saline lake
19
Palustrine, seas. saturated, non-forested
3
Reservoir
20
Ephemeral, forested
4
Large river
21
Ephemeral, non-forested
5
Large estuarine river
22
Arctic/boreal peatland, forested
6
Other permanent waterbody
23
Arctic/boreal peatland, non-forested
7
Notes
The glwd-area-hex layer and glwd-cog-area COG were reconstructed by summing the
34 GLWD per-class area rasters over wetland classes 1–33 (the GLWD distribution's
single total-area COG was empty). Global total = 1,818,743,231 ha (~18.2 Mkm²),
matching the GLWD v2.0 published global wetland extent.
Citation
Lehner, B., et al. (2025). Global Lakes and Wetlands Database (GLWD) version 2.0.
Earth System Science Data, 17, 2277. doi:10.5194/essd-17-2277-2025