Web Services for Hydrology

Elevation data is an essential piece of GIS data for hydrologic applications, but it’s big, not always easy to get and for modeling surface water flow requires specialized processing to become useful. Elevation data and services are coming to ArcGIS Online, including some hydro specific capabilities.

World Elevation Services

The World Elevation Services became available for beta testing last fall and will be released at the end of March. There are image services, data download services, and analysis task services available, as well as sample applications. The services are built from a collection of data sources, ranging from less than a meter resolution up to almost 5 kilometers, and includes services of elevation, shaded relief, slope, and aspect. We will continue to add new data as it becomes available. Like other things on ArcGIS Online these services can be used in Desktop and any other Esri clients, and also in other applications via REST or SOAP. http://resources.arcgis.com/content/imagery/10.0/world_elevation

Hydrologic Services

Since you’re reading the Hydro Blog, your obvious thought is, when can I start using elevation web services for water resources applications? You’ll be happy to know we’re working on it. You’ve probably noticed a shift happening in ArcGIS Online and the Resource Centers to more specific application areas, in places like ArcGIS for Local Government and right here for Hydro.

The goal is to provide domain specific online basemaps, data, and services as part of the overall ArcGIS system. It will include things like database design templates, workflows for building databases and performing spatial analysis, map templates, as well as working examples with source code for services, scripts, and applications.

The first piece for Hydro was the Beta version of the Hydro Basemap, released last year. This map of the United States is available at scales from about 1:47 million to 1:18 thousand scales. The data is derived primarily from the NHDPlus dataset and is symbolized by mean annual flow.

The team is actively working on a World Hydro Basemap that will be available at scales from 147 million to 1 million, which will be available later this year. Along with the Basemaps, we’ll provide map templates so you can create the same maps for your area.

Examples of World Hydro Basemap in South America

In an effort to lower the bar for people who want or need some hydrologic analysis in their GIS or web applications, we are developing a set of geoprocessing workflows and web services for global multiscale watershed delineation and stream tracing. As GIS professionals working in hydrology, this will provide you with “best practice” workflows to build your own data and services, as well as services you can directly use in ArcGIS and your web applications.

Let’s face it, most people don’t know how to hydrocondition a DEM, it’s a tedious job, and everyone shouldn’t be repeating the same work. So we’re developing a methodology to empower authoritative organizations to more easily do their hydroconditioning and stand up scalable, high performance web services against that data. Think of these as foundation services; the building blocks for focused web applications tailored to more specific customers who likely are not GIS people, and maybe not even water people.

So, like the local government application templates cited above, we will also be building similar applications for hydrologic applications that we will be sharing here through the resource center.

Congo basin over world elevation service

An early presentation about the elevation services and hydrologic analysis services is available online in the Esri Proceedings Library: 2011 Geomorphology Proceedings

We will preview this and other hydro work at the American Water Resources Association specialty conference on GIS and Water Resources in March 26-28 in New Orleans. Check back to the Hydro Blog for announcements of the release of the World Hydro Basemap, and the Hydrologic Analysis Services and Applications.

Special thanks to Steve Kopp for providing this post. Questions for Steve: skopp@esri.com

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