Date of Award


Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)


Spatial Information Science and Engineering


Torsten Hahmann

Second Committee Member

M. Kate Beard-Tisdale

Third Committee Member

Max Egenhofer


An abundance of formal ontologies and data models, including a number of standards, exist for the hydrology domain. While some standards have achieved a level of technical interoperability for water data integration and exchange, semantic integration of water data remains a challenge, for a number of reasons. Existing ontologies and data models (1) are mostly fragmented and disconnected, (2) lack foundational grounding, and (3) semantically differ in how hydrological and hydrogeological terms are used. We investigate the use of an emerging, rigorously axiomatized reference ontology for the hydro domain, the Hydro Foundational Ontology (HyFO), to overcome these heterogeneities by integrating the existing hydro ontologies and data models with HyFO. HyFO formalizes general concepts that are central to water storage below and above the ground surface through rigorous and detailed axiomatization in first-order logic. This work presents first results of integrating the Ground Water Markup Language (GWML2), a conceptual model specific for the exchange of groundwater information, with HyFO by grounding GWML2 concepts logically in HyFO’s concepts and relations. The rigorous logical axiomatization of GWML2’s concepts by way of adding semantic precision and clarity results in a first order logic merged ontology that is a consistent extension of HyFO and the foundational ontology DOLCE. It also leads to the development of a stratified subclass hierarchy that realizes three levels of semantic distinctions in GWML2 concepts: (1) the top layer contains generic to earth and physical sciences, (2) the intermediate layer contains HyFO specific concepts that are universal for the surface and subsurface domain, and (3) the bottom layer encapsulates groundwater specific GWML2 concepts. More generally, this work provides a broader benefit by demonstrating how to effectively utilize formal ontological analysis and rigorous axiomatizations in the development and integration of geoscience ontologies.

In addition, this thesis presents a preliminary ontological model that formalizes different hydrologic flow patterns as perdurant processes. Endurant concepts that participate in a flow process are described by a refined set of participation relations. Flow that is confined to a single geophysical endurant, and flow between two different endurants are modeled as Intraflow and Interflow respectively.