Major coastal storms, associated with strong winds are mostly know because of the serious damage they can cause along the shoreline and other threats. Sea storm events on the Catalan coast are often associated with stormy weather phenomena. Furthermore, the earth’s ability to respond to extreme natural events has been limited due to the extent of area used for maritime activities. As such, the receiving environment is not able to respond to the storm surges.   An example of this is the coastal strip of Tossa de Mar. This region occasionally suffers episodes of flooding along the beach and the urban waterfront when the sea level is high and there are strong waves. Flooding in the lower part of Tossa’s core follows a complex pattern, since it depends both on the maritime conditions and on the sediment dynamics of the stream. The conditions from an extreme event in Tossa de Mar in December 2008 were reproduced using actual field data. It displays the simulation results, integrating different numerical modelling tools to develop the model.   Along with numerical simulation tools within the scope of Maritime Engineering (developed by the Laboratory of Maritime Engineering at the UPC), this study also implements tools usually applied in Fluvial Dynamics and Urban Drainage studies (developed at the Flumen Institute for Fluvial Dynamics and Hydrologic Engineering), therefore signifying a notable innovation within the field of Hydraulic Engineering. The latter will ultimately have applicability to the study of floods and the assessment of flood risks in the urban zone of Tossa, if also resulting applicable to other towns with similar predicaments with which the Catalan Coast abounds.   The present study aims at simulating the rough weather of December 26 and 27 2008 (Storm of Sant Esteve) in order to validate a forecasting tool based upon data from the past flood, as well as suggest alternatives or actions to mitigate the risk before a potential incident (i.e. inappropriateness or appropriateness of the removal of the bar that develops at the mouth of the stream, re-outlining of beaches) as well as during the course of an episode (i.e. assessment of the immediate risk according to the climatic conditions, establishment of evacuation routes...).   The obtained results certainly signify a step further over the currently existing work areas on both the development and utilization of both numerical modelling tools that could indeed be implemented in future research projects and subsequently applied to the elaboration of municipal emergency plans.