Global Lakes and Wetlands Database (GLWD) Version 2¶
The Global Lakes and Wetlands Database (GLWD) Version 2 provides a harmonized global database of lakes, rivers, and wetlands at 15 arc-second resolution. This dataset combines and harmonizes multiple ground and satellite-based data products to create a comprehensive map of inland water extents, types, and their intrinsic temporal dynamics.
GLWD v2 represents 18.2 million km² of wetlands (13.4% of global land area excluding Antarctica) classified into 33 types. The classification system differentiates between natural and non-natural lakes, rivers of multiple sizes, and various wetland types incorporating information on: - Seasonality (permanent vs. intermittent vs. ephemeral) - Inundation vs. saturation - Vegetation cover (forested vs. non-forested) - Salinity - Natural vs. non-natural origins - Landscape position and water source (riverine, lacustrine, palustrine, coastal/marine)
Citation¶
Lehner, B., Anand, M., Fluet-Chouinard, E., Tan, F., Aires, F., Allen, G.H., Bousquet, P., Canadell, J.G., Davidson, N., Finlayson, C.M., Gumbricht, T., Hilarides, L., Hugelius, G., Jackson, R.B., Korver, M.C.,
McIntyre, P.B., Matthews, E., Nagy, S., Olefeldt, D., Pavelsky, T., Pekel, J.-F., Poulter, B., Prigent, C., Wang, J., Worthington, T.A., Yamazaki, D., Thieme, M. (in preparation). Mapping the world’s inland waters: an
update to the Global Lakes and Wetlands Database (GLWD v2).
Data Format and Limitations¶
The data is provided in both ESRI© Geodatabase and GeoTIFF formats at 15 arc-second resolution, covering an area from 180° West to 180° East and 56° South to 84° North (excluding Antarctica). The data uses the World Geodetic System 1984 (GCS_WGS_1984) coordinate system. The dataset has several known limitations:
- Data sparsity in certain regions
- Possible classification uncertainties in areas with complex wetland mosaics
- Limited accuracy for areas with rapid land use change
Dataset Components¶
The GLWD v2 dataset in Google Earth Engine consists of several components:
Image Collections¶
- DELTA_AREA_CLASS_PCT: An image collection containing individual images for each of the 33 wetland classes (plus dryland), showing the extent of each wetland class per pixel as a percentage of pixel area. Values range from 0-100%.
Individual Images¶
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GLWD_V2_DELTA_AREA_HA_X10: Shows the absolute area of all wetland classes combined in hectares, multiplied by 10 for precision (i.e., a value of 15 means 1.5 ha). This layer is useful for quantifying total wetland extent.
-
GLWD_V2_DELTA_AREA_PCT: Represents the relative area of all wetland classes combined as a percentage of pixel area (0-100%). This layer helps visualize the density of wetland coverage.
-
GLWD_V2_DELTA_MAIN_CLASS: Identifies the dominant wetland class within each pixel using class IDs 1-33 (0 indicates inland pixels without any wetland coverage). In cases where multiple classes have equal coverage, the lower class ID is chosen.
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GLWD_V2_DELTA_MAIN_CLASS_50PCT: Similar to MAIN_CLASS but only shows the dominant wetland class for pixels where total wetland extent exceeds 50%. Value 0 indicates inland pixels where dryland dominates.
-
GLWD_v2_delta_class_00_pct: Shows the percentage of each pixel that is classified as dryland (non-wetland). Values range from 0-100%.
Wetland Classes¶
The dataset uses band values from 0 to 33 to classify different types of wetlands and water bodies
Expand to show Band Value and Corresponding Class information
| Band Value | Class Name | Description |
|---|---|---|
| 0 | Dryland | Non-wetland areas |
| 1 | Freshwater lake | Natural freshwater lakes |
| 2 | Saline lake | Natural saline/salt lakes |
| 3 | Reservoir | Artificial water bodies |
| 4 | Large river | Major river channels |
| 5 | Large estuarine river | River sections influenced by tides |
| 6 | Other permanent waterbody | Permanent water features not in other categories |
| 7 | Small streams | Minor waterways and tributaries |
| 8 | Lacustrine, forested | Lake-associated forested wetlands |
| 9 | Lacustrine, non-forested | Lake-associated non-forested wetlands |
| 10 | Riverine, regularly flooded, forested | River-associated forested wetlands with regular flooding |
| 11 | Riverine, regularly flooded, non-forested | River-associated non-forested wetlands with regular flooding |
| 12 | Riverine, seasonally flooded, forested | River-associated forested wetlands with seasonal flooding |
| 13 | Riverine, seasonally flooded, non-forested | River-associated non-forested wetlands with seasonal flooding |
| 14 | Riverine, seasonally saturated, forested | River-associated forested wetlands with seasonal saturation |
| 15 | Riverine, seasonally saturated, non-forested | River-associated non-forested wetlands with seasonal saturation |
| 16 | Palustrine, regularly flooded, forested | Marsh-type forested wetlands with regular flooding |
| 17 | Palustrine, regularly flooded, non-forested | Marsh-type non-forested wetlands with regular flooding |
| 18 | Palustrine, seasonally saturated, forested | Marsh-type forested wetlands with seasonal saturation |
| 19 | Palustrine, seasonally saturated, non-forested | Marsh-type non-forested wetlands with seasonal saturation |
| 20 | Ephemeral, forested | Temporary forested wetlands |
| 21 | Ephemeral, non-forested | Temporary non-forested wetlands |
| 22 | Arctic/boreal peatland, forested | Northern forested peat wetlands |
| 23 | Arctic/boreal peatland, non-forested | Northern non-forested peat wetlands |
| 24 | Temperate peatland, forested | Mid-latitude forested peat wetlands |
| 25 | Temperate peatland, non-forested | Mid-latitude non-forested peat wetlands |
| 26 | Tropical peatland, forested | Tropical forested peat wetlands |
| 27 | Tropical peatland, non-forested | Tropical non-forested peat wetlands |
| 28 | Mangrove | Coastal mangrove forests |
| 29 | Saltmarsh | Coastal salt marshes |
| 30 | Delta | River delta wetland complexes |
| 31 | Other coastal wetland | Other coastal wetland types |
| 32 | Salt pan, saline/brackish wetland | Inland saline wetlands and salt flats |
| 33 | Paddy rice | Agricultural wetlands used for rice cultivation |
Earth Engine Snippet¶
// Area by class in hectares (x10)
var glwdAreaHa = ee.Image('projects/earthengine-legacy/assets/projects/sat-io/open-datasets/GLWD/GLWD_V2_DELTA_AREA_HA_X10');
// Area as percentage
var glwdAreaPct = ee.Image('projects/earthengine-legacy/assets/projects/sat-io/open-datasets/GLWD/GLWD_V2_DELTA_AREA_PCT');
// Dominant wetland class
var glwdMainClass = ee.Image('projects/earthengine-legacy/assets/projects/sat-io/open-datasets/GLWD/GLWD_V2_DELTA_MAIN_CLASS');
// Dominant wetland class (>50% coverage)
var glwdMainClass50 = ee.Image('projects/earthengine-legacy/assets/projects/sat-io/open-datasets/GLWD/GLWD_V2_DELTA_MAIN_CLASS_50PCT');
// Dryland percentage
var glwdDrylandPct = ee.Image('projects/earthengine-legacy/assets/projects/sat-io/open-datasets/GLWD/GLWD_v2_delta_class_00_pct');
// Area by class percentage (ImageCollection)
var glwdClassPct = ee.ImageCollection('projects/sat-io/open-datasets/GLWD/DELTA_AREA_CLASS_PCT');
Sample Classes: https://code.earthengine.google.com/?scriptPath=users/sat-io/awesome-gee-catalog-examples:hydrology/GLWD-V2
License¶
GLWD v2 is licensed under a Creative Commons Attribution 4.0 International License. The data is available for public download via hydrosheds
Keywords: wetlands, lakes, rivers, hydrology, water resources, ecosystem, conservation, global dataset
Created by: Lehner et al.
Curated in GEE by: Samapriya Roy
Last updated: 2025-02-19
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