Bora Beran

A semantic annotation tool for hydrologic sciences

Semantic annotations are playing an increasingly important role in the world of metadata, more specifically when dealing with semantic heterogeneities between information systems. The need to bring together disparate data sources (in terms of syntax and semantics) so they can be searched simultaneously from a single search environment has become one of the most challenging tasks in developing information systems that span multiple communities as is common in the geosciences. The key problem lies in the legacy information systems, in which, at the time of development, each system used (and continues to use) its own semantic framework to identify variable codes and names, as well as annotating the collected data with metadata. This lack of a common metadata framework as well the uncoordinated use of descriptors and controlled vocabularies has led to a situation in which synonyms and hyponyms abound. Experience has shown that a centralized system with just one vocabulary for all is not feasible. Rather, in order to overcome these discrepancies it is important to realize that heterogeneity is an inevitable aspect of the scientific data world that needs to be accommodated. This paper describes the development and end use of an application that is designed to connect arbitrary variable names to specific concepts in layered search ontology. We will demonstrate the utility of this application through its deployment for the Consortium for the Advancement of Hydrologic Sciences Inc. (CUAHSI) network of testbeds and report on the issues that emerged carrying out variable and concept tagging. These issues concern specificity of a concept, ancillary information needed when identifying proper ontology locations, and multiple appearances of variables at different locations.

Availability and coverage of hydrologic data in the US geological survey National Water Information System (NWIS) and US Environmental Protection Agency Storage and Retrieval System (STORET)

The need for a unified and improved data access system for the nation’s vast hydrologic data holdings has increased over the past few years as researchers strive for better understanding the human impact on the nation’s water cycle. Large mission oriented data repositories such as the USGS’ National Water Information System (NWIS) and EPA’s Storage and Retrieval System (EPA STORET) play a crucial role in providing a substantial amount of the nationwide coverage, however they do differ regionally in terms of coverage (parameters) and geospatial data density. Besides the differences in geographic distribution, repositories tend to undergo changes in mission statements and as such have different foci in their data collection activities that change as time progresses. This paper places the two water information systems next to each in an attempt to work out the differences in terms of coverage and content and how they complement each other when overlaid. This is done through the use of a number the CUAHSI Hydrologic Information Systems components, namely a web-service suite called WaterOneFlow that permits interrogation of the available data content of a national water metadata catalogue into which these two information systems have been integrated.