Google Earth Engine——HydroSHEDS是基于2000年NASA的航天飞机雷达地形任务（SRTM）获得的高程数据
HydroSHEDS is a mapping product that provides hydrographic information for regional and global-scale applications in a consistent format. It offers a suite of geo-referenced datasets (vector and raster) at various scales, including river networks, watershed boundaries, drainage directions, and flow accumulations. HydroSHEDS is based on elevation data obtained in 2000 by NASA's Shuttle Radar Topography Mission (SRTM).
This hydrologically conditioned elevation dataset is the result of an iterative conditioning and correction process. Note that the conditioning process alters the original DEM and may render it incorrect for applications other than deriving drainage directions. Endorheic basins (inland sinks) are 'seeded' with a no-data cell at their lowest point in order to terminate the flow. Full details of the underlying digital elevation model are available in the HydroSHEDS website and documentation. This dataset is at 3 arc-second resolution. The datasets available at 3 arc-seconds are the Void-Filled DEM, Hydrologically Conditioned DEM, and Drainage (Flow) Direction.
There are two areas with incorrect negative values of -100 close to Vancouver, Canada around (50.16, -123.85) and Australia (-14.96, 129.62)
HydroSHEDS是一个制图产品，以一致的格式为区域和全球范围的应用提供水文信息。它提供了一套不同尺度的地理参考数据集（矢量和栅格），包括河流网络、流域边界、排水方向和流量积累。HydroSHEDS是基于2000年NASA的航天飞机雷达地形任务（SRTM）获得的高程数据。
这个水文条件下的高程数据集是一个反复调节和校正过程的结果。请注意，调节过程改变了原始DEM，可能会使其在推导排水方向以外的应用中变得不正确。内流盆地（内陆汇）在其最低点用无数据单元进行 "播种"，以终止流动。基础数字高程模型的全部细节可在HydroSHEDS网站和文件中找到。该数据集的分辨率为3弧秒。3角秒的数据集是虚空填充DEM、水文条件DEM和排水（流）方向。
在加拿大温哥华附近（50.16，-123.85）和澳大利亚（-14.96，129.62）有两个区域的负值不正确，为-100。
Dataset Availability
2000-02-11T00:00:00 - 2000-02-22T00:00:00
Dataset Provider
WWF
Collection Snippet
ee.Image("WWF/HydroSHEDS/03CONDEM")
Resolution
92.77 meters
Bands Table
| Name | Description | Min* | Max* | Units |
|---|---|---|---|---|
| b1 | Elevation | -440 | 8527 | Meters |
* = Values are estimated
引用：
Lehner, B., Verdin, K., Jarvis, A. (2008): New global hydrography derived from spaceborne elevation data. Eos, Transactions, AGU, 89(10): 93-94.
代码：
var dataset = ee.Image('WWF/HydroSHEDS/03CONDEM');
var elevation = dataset.select('b1');
var elevationVis = {
min: -50.0,
max: 3000.0,
gamma: 2.0,
};
Map.setCenter(-121.652, 38.022, 8);
Map.addLayer(elevation, elevationVis, 'Elevation');