An Integrated Approach to Study the Morphodynamics of the Lignano Tidal Inlet

Abstract

The morphological evolution of a tidal inlet is the combined result of tides and wind waves, which interact in a non-linear manner and over very different time-scales. Likewise, the presence of maritime structures built in the vicinity of the tidal inlet, for coastal or port defense or to stabilize the inlet itself, can greatly affect this dynamic equilibrium, changing erosional and depositional patterns of the adjacent shoreline. In this study, the narrowing phenomenon of the Lignano tidal inlet subsequent to the construction of the related port, is examined through an integrated approach in order to propose and verify a possible form of evolution. This approach is the result of the combination of three methods: the historical reconstruction of the shifting of the coastline, an empirical scheme which describes the qualitative morphology of a mixed-energy tidal inlet, and a process-based morphodynamic modeling, which adopts a bi-dimensional depth averaged (2DH) approach. The application of numerical modeling has required the definition of a reduced input set of data representing an average year, in particular for wind and tidal conditions, including the meteorological component. The magnitude and the directions of the simulated dominant sediment transport are coherent with real processes both from a qualitative and a quantitative point of view.