Browsing by Subject "Hydrologic data"

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Multi-scale hydrological information system using an OGC standards-based architecture
(2011-05) Dong, Jingqi; Maidment, David R.; Hodges, Ben
A Multi-Scale Hydrological Information System (HIS) includes three levels of HIS, which are the national CUAHSI HIS, the Texas HIS and the local Capital Area Council of Governments (CAPCOG) HIS. The CUAHSI Hydrologic Information System has succeeded in putting water data together using a Services-Oriented Architecture (SOA). However, maintaining the current metadata catalog service has been problematic. An Open Geospatial Consortium (OGC) standard transformation procedure is happening to transfer the current web services into OGC adopted services and models. The transformation makes CUAHSI HIS compliant with the international OGC standards and to have the capability to host tremendous water data. On a scaled down level, the Texas HIS has been built for the specific Texas hydrologic data, concerning the variables and the web services listed in this thesis. The CAPCOG emergency response system was initiated for the purpose of the Texas flash flood warning, including several data services, such as the USGS NWIS, the City of Austin (COA) and the Lower Colorado River Authority (LCRA). By applying the consistent mechanism, which is the OGC standards-based SOA, in these three scales of HIS, three catalogs of services can be created within the architecture, and hydrologic data services included in different catalogs can be searched across. Each catalog of services has a different scale or purpose. A technique, called KiWIS developed by the KISTERS Company, of publishing OGC standard web services through the WISKI hydrologic database was then described. The technique has been applied to the City of Austin’s water data hosted at CRWR. The OGC standard transformation progress reviewed in the thesis and the technique described can give a reference on how to synthesize Multi-Scale HIS within a standard mechanism.
A services stack architectural model for the CUAHSI-HIS
(2010-12) Seppi, James Adam; Maidment, David R.; Hodges, Ben R.
The Hydrologic Information System Project of the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI) has successfully created a large-scale prototype Hydrologic Information System (HIS). This system catalogs and provides access to over 23 million time series of hydrologic data, which are distributed across the United States at various academic, research, and governmental data providers. The service-oriented architecture that enables the HIS comprises distributed hydrologic data servers, a centralized series catalog, and various client software applications, and is supported by WaterML, a standardized language for transmission of hydrologic data. The current architectural model, termed the Network-Observations Model, of the HIS relies on a searchable central catalog of series metadata. Harvesting series metadata from large federal data providers, such as the USGS, EPA, and NCDC, has proven a laborious undertaking and involves custom database migration tools. This time-consuming harvesting task, coupled with a multitude of custom-coded solutions at the central series catalog has led to concerns with the long-term sustainability of the current architectural model. A new architectural model, termed the Services Stack Model, is proposed in this thesis. In the proposed model, a catalog of services metadata, rather than of series metadata is used to connect hydrologic data consumers with data providers. Internationally-recognized web service and data encoding standards, including the upcoming WaterML2.0 specification, from the Open Geospatial Consortium are used as the backbone of the new model. The proposed model will hopefully lead to greater acceptance of the CUAHSI-HIS, and result in increased sustainability and reduced maintenance of the system in the long-term.