| Summary: | 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 (-180º, 180º, -90º, 90º) 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 60º North, the raster resolution of the data is 3-arc-seconds, corresponding to the resolution of the SRTM. For the areas North of 60º, 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.
|
|---|