CUAHSI CYBERINFRASTRUCTURE FOR HYDROLOGIC SCIENCES

The mission of the CUAHSI HIS (Consortium of Universities for the Advancement of Hydrologic Science, Inc., Hydrologic Information System) project is development of cyberinfrastructure supporting advanced hydrologic research and education. It is a collaborative project which involves several research universities and the San Diego Supercomputer Center as the technology partner. Over the last three years, the CUAHSI HIS team has been researching, prototyping, and implementing web services for discovering and accessing a variety of hydrologic data sources, and developing applications for the desktop and for the Web.

The CUAHSI HIS system architecture is envisioned as a component of a large scale environmental observatory effort, which emerges as a network of seamlessly integrated data collection, information management, analysis, modeling and engineering endeavors implemented across disciplinary boundaries. The HIS design follows the open services-oriented architecture model, i.e. it relies on a collection of loosely coupled self-contained services that communicate with each other and can be called from multiple clients in a standard fashion. The core of the system is WaterOneFlow SOAP services providing uniform access to multiple heterogeneous repositories of hydrologic observation data, both remote and local. The services follow a common XML messaging schema named CUAHSI WaterML, which includes constructs for transmitting observation values and time series, as well as observation metadata including information about sites, variables and networks. The information model of WaterML follows that of Observation Data Model (ODM, http://www.cuahsi.org/his/odm.html), while extending it to handling of observation data available as fields. The currently available services provide access to USGS NWIS, EPA STORET, NCDC ASOS, Daymet, MODIS and NAM12K data, as well as to data maintained by users in the ODM format.

The web services are accessed from different types of clients, including Web browser, a range of desktop applications such as Matlab, ArcGIS and Excel, and several programming languages (NET and Java) which were exposed as the primary desktop client environments by the CUAHSI user needs assessment. The general organization of the HIS System is shown in Figure 1. The web browser-based client is developed in collaboration with ESRI, and relies on ArcGIS Server 9.2 for online mapping functionality.

Figure 1 near here

At the physical level, the system being deployed now, includes a central HIS server and a networked collection of workgroup HIS servers. The central node contains observation data catalogs for nation-wide hydrologic observations repositories maintained at USGS, EPA, NCDC, and other agencies. The catalogs are accessible via the web services supporting GetSiteInfo and GetVariableInfo requests, while the data series are returned via GetValues SOAP API calls. The organization of Workgroup HIS nodes is similar, with additional ability to import local observation data into ODM instances, configure the ODM and respective web services, and serve the newly registered data along with the national hydrologic observations. The software stack for both the Central and the Workgroup HIS servers is based on Windows 2003 server and includes SQL Server 2005, ArcGIS Server 9.2, Visual Studio 2005, as well as a series of tools and databases developed by the HIS team.

In the first stage of deployment, the workgroup HIS servers are designed to be implemented at 11 hydrologic observatory testbeds as part of an NSF WATERS initiative. This will let us test the HIS tools on diverse hydrologic datasets collected by the testbeds and help further develop the Cyberinfrastructure for Hydrologic Sciences.

More information about the project is available at http://www.cuahsi.org/his.

Figure 1. A high-level view of the HIS organization