World Hydro Reference Overlay

The World Hydro Reference Overlay Map service is designed to be used as a base map by scientists, professionals, and researchers in the fields of Hydrology, Geography, Climate, Soils, and other natural sciences. The map features a hydro-centric design based on the amount of water flowing within the drainage network such that symbols of the same size and color represent roughly the same amount of water. This map shows surface water flow as a linear phenomenon even over and through bodies of water. Using the best available data we show relative flow accurately, so that if one river carries more water downstream than another river, the result will be that the river will have a thicker symbol on the map. This map is used as an overlay for content such as elevation from the World Terrain Base service or thematic services such as soil units, vegetation, or ecoregions. Combined with a basemap and your map services, this map provides a frame of reference for showing regional, national, and continental hydrologic phenomena such as drought, runoff, river level monitoring and flood forecasting. River names are collected in the UTF8 character set, so river names are collected in their original language, but are written in the Roman alphabet. Sources for all river names are from the open source geonames.org project so they are international by nature. The map is compiled from several sources. The global scales (very small scales through 1:2,300,000) include content from: HydroSHEDS, GTOPO30 Global Topographic Data, SRTM, GLWD, WorldClim, GRDC, and WWF Global 200 Terrestrial Eco Regions, with the latter three providing the inputs and basis for calculating flow. At medium scales (1:36,000 to 1:2,000,000) this service currently contains only U.S. data and that was derived from the NHDPlus program that was jointly produced by the USGS, EPA, and Horizon Systems. Description: http://downloads.esri.com/blogs/arcgisonline/esrilogo_new.png This work is licensed under the Web Services and API Terms of Use.View Summary | View Terms of Use World Wildlife Fund HydroSHEDS This product, the World Hydro Reference Overlay, incorporates data from the HydroSHEDS database which is © World Wildlife Fund, Inc. (2006-2012) and has been used herein under license. WWF has not evaluated the data as altered and incorporated within the World Hydro Reference Overlay, and therefore gives no warranty regarding its accuracy, completeness, currency or suitability for any particular purpose. Portions of the HydroSHEDS database incorporate data which are the intellectual property rights of © USGS (2006-2008) (data available from U.S. Geological Survey, EROS Data Center, SD), NASA (2000-2005), ESRI (1992-1998), CIAT (2004-2006), UNEP-WCMC (1993), WWF (2004), Commonwealth of Australia (2007), and Her Royal Majesty and the British Crown and are used under license. The scientific citation for the HydroSHEDS database is: Lehner, B., Verdin, K., Jarvis, A. (2008): New global hydrography derived from spaceborne elevation data. Eos, Transactions, AGU, 89(10): 93-94.