Marine sediment characterization of heavily populated areas. Experimentation through fuzzy logic,Caratterizzazione dei sedimenti marini di aree fortemente antropizzate. Sperimentazione mediante logica fuzzy

An ontological approach in GIS serves as a framework for the conceptualization of processes in the real world. In this paper, we examine an application of sediment characterization in the Augusta Harbour, located in the Eastern part of Sicily Island (Italy) and connected to the open sea by two entrances. The use of ontology helps to define a specific scenario grounded on the abilities from an existing spatial dataset. The ontology depends both on the model-maker and on the context, and may be different for different users. In fact, the degree of conceptualization, which underlies the language used by a particular knowledge base, varies depending on the purpose. A comparison between the fuzzy-based scenario and the existing spatial dataset carried out in the study area shows areas suitable and unsuitable for potentially contaminated sediments. A sensitivity analysis applied to the area illustrates a significant increase of object suitable for classification when bathymetry, and distance from the contaminating sources are decreased within the lower limit while the sediments thickness is increased. So that inaccuracies in attributes influence the determination of the objects. The sensitivity of the model shows that artificial boundaries for the contaminated areas are not reasonable and consequently should be treated as vague objects.