Hydrologic Derivatives for Modeling and Applications (HDMA) Data

The Hydrologic Derivatives for Modeling and Analysis (HDMA) database provides comprehensive and consistent global coverage of raster and vector topographically derived layers. The HDMA includes five raster layers: digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI); and three vector layers: streams, catchment boundaries, and processing units. The coverage of the data is global (-180, 180, -90, 90) with the underlying DEM being a hybrid of three datasets: HydroSHEDS (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales), Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) and the Shuttle Radar Topography Mission (SRTM). For most of the globe south of 60 North, the raster resolution of the data is 3-arc-seconds, corresponding to the resolution of the SRTM. For the areas North of 60, the resolution is 7.5-arc-seconds (the smallest resolution of the GMTED2010 dataset) except for Greenland, where the resolution is 30-arc-seconds. The streams and catchments are attributed with Pfafstetter codes, based on a hierarchical numbering system, that carry important topological information.