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This research is focused on the application of water indexes derived from historical Landsat image series to quantify the impact caused by anthropic activities on wetlands. This work is focused specifically on the Bajo Sinú Wetlands Complex (BSWC) located on the northern Colombian Caribbean Coast. We modelled the spatio-temporal dynamics of the BSWC in three specific periods (1991, 2003 and 2015) and during two seasons: dry and wet. We used data from Landsat 4 Thematic Mapper (TM), Landsat 7 Enhanced Thematic Mapper Plus (ETM) and Landsat 8 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) (Oli-Tirs) images, based on which we evaluated seven different water indexes in order to select the one which best describes changes in the BSWC.The modelling consisted of the identification of spatio-temporal changes over the BSWC caused by two main pressure factors: (1) anthropic activity in the Sinú River Watershed, which is the main water source of the BSWC and (2) the launch of the Urrá Hydroelectric Dam Project located in the upper basin of the Sinú River in 2000.The most suitable water index was found to be the Normalized Difference Water Index (NDWI), based on which we acquired water index images and digital classifications. Reliability of these products was rated in terms of the Overall Classification Accuracy values above 87% and a Kappa index between 0.75 and 0.86.We found that over the 25 year study period, the maximum water storage capacity decreased by 56.2%, the number of the waterbodies reduced by 24.7%, and the average size of the waterbodies decreased by 41%. All the results indicate a deterioration of the water storage capacity in the BSWC.

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This PhD thesis highlights the importance of the semantic interoperability in the process of harmonization, structuring and integration of the knowledge in geographical and environmental domains. The objective of this research is to formulate a strategy that contributes to the synthesis, conceptualization and integration of knowledge associated with geographical and environmental science. This strategy uses knowledge of Biodiversity as a reference and the ontologies as tools in the context of semantic interoperability.The formulation of this strategy is justified from the context of the type of knowledge to which it is directed. The knowledge associated to geographical and environmental applications (called in the framework of this research "geospatial thematic applications") can be categorized as complex because its understanding requires different processes such as: integrating information from different sources; generating inferences; linking the new information with the existing knowledge and coordinating different representations and perspectives like for example the synthesis at different spatial and temporal scales. The complexity of the knowledge associated to these domains determines its nature of dispersion, which in turn reflects the lack of information integration. The strategy of semantic interoperability is made up of three components: 1) the formulation of a methodology for the knowledge acquisition in the context of the development of ontologies for the geographical and environmental applications. This methodology has been called ACATGeo, 2) the development of ontologies or ontological networks for a thematic application associated to the domains mentioned before, through the combination of the ACATGeo methodology and a methodology for the ontology building, and 3) the use of such ontologies as a mean to generate RDF documents of integration of data from different databases. The combination of these three components is in itself a protocol that can be replicated in the context of any thematic application associated with geographical and environmental domains Given the complexity of knowledge associated with geospatial thematic applications, and taking into account the superficiality in the process of knowledge acquisition in current methodologies for building ontologies, the formulation of the methodology ACATGeo (knowledge acquisition in the ontology development framework for geospatial thematic applications) is proposed as the first component of the semantic interoperability strategy:The application of ACATGeo allows to synthesize and conceptualize the knowledge that transcends various domains and that is synthesized at different spatial-temporal scales. This knowledge was structured in three elements: an Integrated Conceptual Framework of the knowledge, a glossary of terms and a data model. Those elements were the basis for the formalization of the knowledge in ontological network. This strategy of semantic interoperability was proved for the knowledge integration in the domain of Biodiversity....