Representing time over the Semantic Web has always been a challenging issue that many scientific works were interested to address. To the best of our knowledge, the most important ones focused on models, whereas Semantic Web and especially OWL 2 offers semantics that can be efficiently used to describe qualitative diachronic information (i.e. information evolving in time and which start and/or end time is unknown). In this work, we show the relationship between the OWL 2 semantics and the representation of time intervals; then we introduce a qualitative representation of temporal information based on a set of SWRL rules, that allows a sound and complete reasoning mechanism.