HydroSHEDS analysis workflow: drainage grids, river networks, and basin analysis in GIS

What the HydroSHEDS analysis workflow contains

The core HydroSHEDS v1 workflow begins with elevation-derived grids. The project identifies a void-filled digital elevation model, a hydrologically conditioned elevation model, flow-direction grids, flow-accumulation grids, flow-length grids, and land-mask layers. Flow direction encodes the direction water moves from one cell to the next; flow accumulation summarizes the upstream contribution to each cell; and flow length measures distance through the modeled drainage system in upstream or downstream directions. These layers are designed for hydro-environmental model development and custom GIS applications, and the project explicitly describes them as hydrographic baseline information rather than thematic or attribute-rich data. (hydrosheds.org)

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• •HydroSHEDS v1 core rasters: void-filled DEM, conditioned DEM, flow direction, flow accumulation, flow length, and land mask.
• •HydroSHEDS v2 core layers: flow direction, flow accumulation by cell count, flow accumulation by true catchment area, a derived river network, and a beta drainage-basin layer.
• •Related secondary products: HydroBASINS catchment polygons, HydroRIVERS river reaches, HydroLAKES lake polygons, and HydroATLAS attribute databases.
• •HydroSHEDS v2 currently provides 1-arc-second data, approximately 30 meters at the equator, and uses a 1-square-kilometer upstream-area threshold to define its released river network. (hydrosheds.org)

Geography, resolution, and update cadence

HydroSHEDS v1 is intended as a global hydrographic framework, but its source conditions vary by latitude. The v1 core products are derived primarily from the SRTM elevation model at 3 arc-seconds, approximately 90 meters at the equator, with custom modifications. Because SRTM coverage does not extend above 60 degrees north, the project states that v1 products in that region rely on the coarser HYDRO1k elevation model and are unavailable at the highest 3-arc-second resolution. Analysts should therefore avoid treating the nominal global label as evidence of uniform spatial quality. (hydrosheds.org)

HydroSHEDS v2 is a newer generation derived from TanDEM-X elevation data. The currently released v2 geography is limited to North and South America, with additional regions and layers described as future releases. This makes v2 attractive for high-resolution work in the Americas but unsuitable as a complete global replacement for v1 at the time of writing. (hydrosheds.org)

• •v1 nominal resolutions: 3, 15, and 30 arc-seconds, plus 5 and 6 arc-minutes, depending on the layer.
• •v2 resolution: 1 arc-second, approximately 30 meters at the equator.
• •v2 current geography: the Americas only, rather than global coverage.
• •Update cadence: no fixed recurring schedule is stated in the official documentation; releases are version- and product-specific.

Formats, access methods, and a defensible workflow

HydroSHEDS v1 core rasters are distributed primarily as GeoTIFF files. The official download page offers continental and global products at coarser resolutions, while 3-arc-second layers are available as continental files or 10-by-10-degree tiles. The page also identifies older BIL and GRID archives for users who still require the obsolete v1.0 formats. HydroSHEDS v2 distributes its raster layers as cloud-optimized GeoTIFFs in 10-by-10-degree tiles and regional composites. Its vector river and basin products are available as zipped Esri File Geodatabases and OGC GeoPackages. (hydrosheds.org)

A defensible workflow starts by selecting the correct product generation. Use v1 when global consistency or a mature global baseline matters; use v2 when the study area is in the Americas and approximately 30-meter drainage structure is appropriate. Download only the layers required for the computation, preserve the original files, and record checksums or equivalent file metadata when building a repeatable pipeline.

• •Download from the official HydroSHEDS product and download pages rather than relying on unmonitored third-party mirrors.
• •Keep v1 and v2 products in separate data namespaces; do not silently mix their flow encodings, resolutions, or derived geometries.
• •Avoid resampling flow-direction rasters with continuous interpolation. Use categorical or nearest-neighbor handling where reprojection is unavoidable.
• •Use ACA for area-based thresholds when available; do not infer square kilometers from ACC without accounting for latitude-dependent cell area.
• •Validate basin outlets, coastal sinks, inland sinks, and tile-edge behavior before publishing derived catchments.

Suitable GIS workflows and interpretation cautions

HydroSHEDS is well suited to watershed delineation, upstream-area screening, drainage-density studies, river-network tracing, terrain-informed environmental analysis, and spatial aggregation by catchment. It can also provide a useful organizing geography for combining freshwater structure with roads, buildings, infrastructure, land cover, imagery, climate observations, or public records. In those workflows, HydroSHEDS contributes modeled drainage relationships; it does not establish the current condition, legal status, ownership, or operational status of an asset or waterbody.

The principal limitation is that HydroSHEDS is an elevation-derived hydrographic model. A modeled flow path is not automatically a surveyed channel, a flood boundary, a stormwater pipe, or a current local drainage asset. Bridges, culverts, levees, canals, urban grading, karst systems, reservoirs, glaciers, wetlands, and coastal or endorheic basins can all require local interpretation. The official v1 description also notes that the core products provide limited thematic or attribute information, while v2 states that future releases will add more attributes through HydroATLAS and HydroRIVERS. (hydrosheds.org)

• •Strong use cases include basin-level aggregation, upstream contributing-area analysis, river-network context, environmental screening, and global or continental comparisons.
• •Do not interpret a HydroSHEDS raster as a real-time hydrologic observation, flood forecast, stormwater inventory, or complete local stream map.
• •Resolution, latitude, source elevation, hydrologic conditioning, and basin treatment can materially affect results.
• •A HydroSHEDS-derived result should retain source version, layer name, resolution, region, processing method, and validation notes.

License, strengths, and tradeoffs

Licensing is product-specific. HydroSHEDS v1 core products are described as freely available for scientific, educational, and commercial use under a specific license agreement included in the technical documentation. HydroSHEDS v2 core products are described as freely available for scientific, educational, and commercial use under a Creative Commons Attribution 4.0 license. Related products such as HydroBASINS can share the core-product license, while other HydroSHEDS-family datasets may use different terms. Review the product-specific license and citation requirements before redistribution, publication, or commercial integration. (hydrosheds.org)

• •Strength: a coordinated family of raster and vector products supports consistent drainage analysis from cells to basins and river reaches.
• •Strength: multiple resolutions and tile structures make it practical to choose between global context, continental processing, and high-resolution regional work.
• •Strength: the data are designed for GIS and modeling workflows and are available in widely supported formats, including GeoTIFF, File Geodatabase, and GeoPackage.
• •Tradeoff: v1 quality and resolution are not uniform globally, particularly at high northern latitudes.
• •Tradeoff: v2 is higher resolution but currently limited to the Americas and remains an evolving release.
• •Tradeoff: core layers contain limited thematic attributes, so analysts often need to join other datasets for land cover, water quality, infrastructure, climate, ownership, or current observations.
• •Tradeoff: the project has no single universal license or fixed update cadence across its entire product family; terms and freshness must be checked product by product.