Before anything is computed per pixel, the land surface is divided. The basin mask assigns every one of the 22.26 billion land pixels to one of 24,587,290 basins, from the Amazon down to single-pixel coastal outlets. The region mask groups whole basins into 96 regions, each small enough to process and to download on its own; no basin is cut by a region edge. These two masks are the first layers in the release, and every later step works one region at a time. Pick a region on the map for its FullBasin package, the MERIT Hydro 5°×5° tiles it was computed from, and its window on the global 90 m grid. The MERIT Hydro layers are not redistributed here; you obtain them from their own archive under their terms.
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Point your phone’s camera at the code, then tap the link that appears.
fullhydro.org