Hydrologic Derivatives for Modeling and Analysis (HDMA) database -- South America

This contains the South American portion of the Hydrologic Derivatives for Modeling and Analysis (HDMA) database. The HDMA database provides comprehensive and consistent global coverage of raster and vector topographically derived layers, including raster layers of digital elevation model (DEM) data, flow direction, flow accumulation, slope, and compound topographic index (CTI); and vector layers of streams and catchment boundaries. 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.

本数据集包含用于建模与分析的水文衍生数据库（Hydrologic Derivatives for Modeling and Analysis，HDMA）的南美区域数据。HDMA数据库提供覆盖全球的、一致且全面的栅格与矢量地形衍生图层产品，其中栅格图层包含数字高程模型（digital elevation model，DEM）数据、流向、汇流累积量、坡度以及复合地形指数（compound topographic index，CTI）；矢量图层则包含水系与流域边界。该数据集的全球覆盖范围为(-180°, 180°, -90°, 90°)，其基础DEM由三类数据集融合而成：HydroSHEDS（基于多尺度航天飞机高程衍生数据的水文数据与地图集）、全球多分辨率地形高程数据2010（Global Multi-resolution Terrain Elevation Data 2010，GMTED2010）以及航天飞机雷达地形测绘任务（Shuttle Radar Topography Mission，SRTM）。全球北纬60°以南的大部分区域，栅格数据分辨率为3角秒，与SRTM的分辨率一致；北纬60°以北的区域，分辨率为7.5角秒（为GMTED2010数据集的最小分辨率），但格陵兰岛除外，其分辨率为30角秒。水系与流域边界附带基于分级编号系统的普法夫斯特特编码（Pfafstetter codes），该编码承载了重要的拓扑信息。