MERIT-FullBasin: A global 90-meter basin dataset with a per-pixel upstream index and morphometric attributes

Abstract. Fine-resolution hydrographic data are essential for flood prediction and risk mapping, large-sample hydrology, and machine-learning streamflow models. Yet no existing global product simultaneously provides basin identity, upstream-catchment topology, and morphometric attributes at per-pixel resolution. The 90 m MERIT-Hydro flow-direction and flow-accumulation rasters are the input, but computing per-pixel attributes from this 75-billion-pixel global grid exceeds the memory limits of standard geographic information system (GIS) software, and tile-based workflows fragment basins across boundaries. Here we present MERIT-FullBasin, a globally seamless dataset that delivers all three layers at per-pixel 90 m resolution. The first tier delineates 340,991 basins above 1 km² in upstream drainage area, together covering over 99.5 % of global land and partitioning the MERIT-Hydro land mask without gaps. The second tier provides a per-pixel depth-first search interval index (dfs_in, dfs_out); a single interval-containment comparison returns the complete upstream catchment of any target pixel, and the index losslessly encodes the underlying D8 flow-direction raster. The third tier delivers sixteen per-pixel upstream morphometric attribute rasters (eight terrain statistics and eight basin-shape metrics) at pixels with an upstream drainage area of at least 10 km². The full pipeline completes in about 21 hours on a single 13-thread, terabyte-memory high-performance computing node. Each tier is verified independently: tier 1 by exact pixel-count match against the flow-accumulation reference, tier 2 by exact reconstruction of the D8 raster from the index alone, and tier 3 by perimeter benchmarking against three independent reference implementations. Products are distributed as GeoTIFFs co-registered with MERIT-Hydro together with per-basin attribute tables. Per-pixel queries reduce to a single GeoTIFF read or a single table lookup. Among published global hydrographic products, MERIT-FullBasin is the first dataset distributed as a per-pixel queryable flow-tree index. The dataset is openly available at https://doi.org/10.5281/zenodo.20344113 (Jiang et al., 2026).