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FullHydro dataset

FullBasin on MERIT Hydro · 90 m

Based on MERIT DEM (Yamazaki et al., 2017) and MERIT Hydro (Yamazaki et al., 2019). This collection uses the native 3 arc-second grid, approximately 90 m at the equator.

This release

Version 1.1 · in development — its pages are here and its archive is being prepared.

What changed from 1.0

  • The basin mask and the region mask are computed by the FlowDivide package.
  • The region mask has 90 regions where 1.0 had 96. A region is now one HydroBASINS Level-02 unit when that unit fits in 2³¹ pixels, the most a 32-bit integer can index. A unit that does not fit is divided along its Level-03 units. Of the 61 coded units, 57 fit as they are; four — 35, 56, 77 and 91 — are divided.
  • The region IDs are short: two digits for a whole Level-02 unit, four for a part of one: the two-digit unit followed by the last digit of the first and of the last Level-03 unit in that part, so 9134 holds 913 and 914.
  • The same basins are also gathered into basin groups along the HydroBASINS Level-01, Level-02 and Level-03 units: 34, 86 and 316 groups.
  • Nothing else changes. The 24,587,290 outlets keep their IDs and their pixel counts, and the per-pixel layers are unchanged.

Earlier releases

Version 1.0 · released 22 May 2026 · 10.5281/zenodo.20344113 — the files released so far, and the version the paper in discussion at Earth System Science Data describes. Its pages stay here for anything that cites it. Once the paper is accepted, 1.1 replaces it on this page; the 1.0 pages and the Zenodo record stay online, marked as superseded, so anything citing 1.0 still resolves.

MERIT Hydro and FullBasin

What comes from MERIT Hydro

The terrain and the baseline hydrography: dir, elv, upa, upg, wth, hnd. We do not redistribute any of them. Register on the MERIT Hydro page (CC BY-NC 4.0 / ODbL) and cite Yamazaki et al. (2019).

What FullBasin adds

Everything computed on top of that grid: the basin and region masks, the per-pixel upstream index, and sixteen upstream attributes, released with a DOI. Licence by layer: the upstream index (dfs_in, dfs_out) under MERIT Hydro’s ODbL 1.0 terms; everything else CC BY 4.0.

Each layer comes from one of the Flow packages: the basin and region masks from FlowDivide, the per-pixel upstream index from the depth-first order FlowTopo builds, and the sixteen upstream attributes from FlowMorph. Run the same packages on another D8 grid, with its elevation, and you get the same layers there.

FullBasin and MERIT Hydro sit on the same 3 arc-second grid, so they line up pixel for pixel. This means FullBasin can tell you exactly which MERIT tiles a basin needs before you download anything.

See the basin and region masks, and the MERIT tiles each region needs