Data Category: 
hydrology
Data Last Access: 
Wednesday, 9 October, 2019
Data JRC Contact Info: 
cesar.carmona-moreno@ec.europa.eu
Data Credits: 
Dai Yamazaki, Mark A. Trigg, Daiki Ikeshima, Development of a global ~90m water body map using multi-temporal Landsat images, Remote Sensing of Environment, Volume 171, 2015, Pages 337-351, ISSN 0034-4257, http://dx.doi.org/10.1016/j.rse.2015.10.014.
Data Availability: 
REGISTRATION REQUIRED
Data Use Limitations: 
Agreement to Terms and Conditions is required for using G3WBM. Please e-mail the developer to acquire a password for downloading G3WBM data. Contact: Dai Yamazaki: yamadai@rainbow.iis.u-tokyo.ac.jp.
Data temporal frequency: 
not specified
Data Spatial Extent: 
Data Region of Interest: 
World
Data Short Description: 
Global Water Body Map (G3WBM)
Data Extended Description: 
A Global 3 arc-second Water Body Map (G3WBM) is developed using an automated algorithm to process multi-temporal Landsat images from the Global Land Survey (GLS) database. We used 33,890 scenes from 4 GLS epochs in order to delineate a seamless water body map, without cloud and ice/snow gaps. Permanent water bodies were distinguished from temporal water-covered areas by calculating the frequency of water body existence from overlapping, multi-temporal, Landsat scenes. By analyzing the frequency of water body existence at 3 arc-second resolution, the G3WBM separates river channels and floodplains more clearly than previous studies. This suggests that the use of multi-temporal images is as important as analysis at a higher resolution for global water body mapping. The global totals of delineated permanent water body area and temporal water-covered area are 3.25 and 0.49 million km2 respectively, which highlights the importance of river-floodplain separation using multi-temporal images. The accuracy of the water body classification was validated in Hokkaido (Japan) and in the contiguous United States using 30 an existing water body databases. There was almost no commission error, and about 70% of lakes >1 km2 shows relative water area error <25%. Though smaller water bodies (<1 km2) were underestimated mainly due to omission of shoreline pixels, the overall accuracy of the G3WBM should be adequate for larger scale research in hydrology, biogeochemistry, and climate systems and importantly includes a quantification of the temporal nature of global water bodies.