Modelling of tides, waves and currents in coastal waters, hydrodynamics of the Firth of Clyde and of the east coast of Scotland

The thesis here presented is based on three main parts. The first part of the thes is based on modelling the water circulation of the Clyde Sea, in order to understand the dynamics of the dispersion of the Neprophs larvae. Previous researches in this area of Scotland highlighted the importance of the temperature- and saline-driven circulation in the Clyde Sea. However, few researches were focused on the surge dynamics, that are governing the dynamics of the water level in winter.;A three-dimensional finite-volume model was used to simulate the surge propagation, while a historical re-analysis was applied to understand the pattern and the propagation of the surge wave in the Clyde.The results highlighted that the largest storms that hit the Clyde in the past 30 years were mostly generated in the North Atlantic. Most interestingly, the results also suggest that severe surges are not only caused by extreme surge events, but also by the coupling of spring high tides with moderate surges.;In the second part the coupled dynamics of waves, tides and wind-driven circulation in the east coast of Scotland are studied. Wave-Current Interactions (WCI) are particularly relevant close to the coastline, where the effect of the spectral dispersion and wave breaking are more important and where the currents are stronger. The results showed that the coupling of strong currents with large waves travelling inopposite direction could enhance in east coast of Scotland the significant wave height (Hs) up to 3 m, threatening potentially infrastructures and ships near the coastline.;The last part of the thesis was dedicated to an experimental study of rogue waves in crossing sea. Crossing sea is one of the most common state in world seas, and occurs when a wind-generated wave train interact with another train of waves, that can be swell waves or another wind-generated wave train, maybe caused by a rapidly turning wind direction. Some numerical studies showed that this interaction can lead to the mechanism of modulation instability and, consequently, to the formation of rogue waves. A water tank experiment was carried out to confirm this theory.;The results shows that the angle of the interaction is a fundamental variable that can decrease or increase the instability of the wave train. However, most interestingly, in the sameconditions, the monochromatic sea state was showing a larger number of rogue waves than the crossing sea.The thesis here presented is based on three main parts. The first part of the thes is based on modelling the water circulation of the Clyde Sea, in order to understand the dynamics of the dispersion of the Neprophs larvae. Previous researches in this area of Scotland highlighted the importance of the temperature- and saline-driven circulation in the Clyde Sea. However, few researches were focused on the surge dynamics, that are governing the dynamics of the water level in winter.;A three-dimensional finite-volume model was used to simulate the surge propagation, while a historical re-analysis was applied to understand the pattern and the propagation of the surge wave in the Clyde.The results highlighted that the largest storms that hit the Clyde in the past 30 years were mostly generated in the North Atlantic. Most interestingly, the results also suggest that severe surges are not only caused by extreme surge events, but also by the coupling of spring high tides with moderate surges.;In the second part the coupled dynamics of waves, tides and wind-driven circulation in the east coast of Scotland are studied. Wave-Current Interactions (WCI) are particularly relevant close to the coastline, where the effect of the spectral dispersion and wave breaking are more important and where the currents are stronger. The results showed that the coupling of strong currents with large waves travelling inopposite direction could enhance in east coast of Scotland the significant wave height (Hs) up to 3 m, threatening potentially infrastructures and ships near the coastline.;The last part of the thesis was dedicated to an experimental study of rogue waves in crossing sea. Crossing sea is one of the most common state in world seas, and occurs when a wind-generated wave train interact with another train of waves, that can be swell waves or another wind-generated wave train, maybe caused by a rapidly turning wind direction. Some numerical studies showed that this interaction can lead to the mechanism of modulation instability and, consequently, to the formation of rogue waves. A water tank experiment was carried out to confirm this theory.;The results shows that the angle of the interaction is a fundamental variable that can decrease or increase the instability of the wave train. However, most interestingly, in the sameconditions, the monochromatic sea state was showing a larger number of rogue waves than the crossing sea