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.

On the Tidal Prism: The Roles of Basin Extension, Bottom Friction and Inlet Cross-Section

“…The inlet shape can in turn directly affect the hydrodynamic field in the enclosed basin in terms of current velocities and tidal level amplitudes, and therefore sediment transport. This is the case for the Lignano tidal inlet, one of the six inlets of the Marano and Grado lagoon, in the northern Adriatic Sea in Italy, which has undergone important morphological changes over the last four decades [4,16]. The construction of the protective pier of Marina Punta Faro located on the internal side of the Lignano inlet resulted in a narrowing of the inlet itself.…”

Improvement in the Sediment Management of a Lagoon Harbor: The Case of Marano Lagunare, Italy

“…With this in mind, an accurate analysis of tides and winds was carried out, to identify the events responsible for port silting within an average year. In particular, the zero-crossing analysis conducted on the tidal oscillation recorded by the Grado tide gauge from 1991 to 2014 showed a mean amplitude of tidal wave height equal to ±0.40 m [69]. For this reason, the tidal oscillation has been represented through a sine curve, having a period of 12 h and an amplitude equal to ±0.40 m [69].…”

“…The resulting mesh consists of about 216,000 quadrangular elements, with a size length ranging between 0.8 and 550 m. A detail of the port is depicted in Figure 5. Manning roughness coefficients and the bottom height for the lagoon and the sea have been assigned as in Petti et al [69], where the bottom height refers to the surveys conducted in 2009-2011 [43]. With reference to Manning roughness coefficients, the port channels were considered as lagoon channels, and the emerged artificial island in front of Marano was treated as dry land.…”

Fortescue Inlet: Offshore Deposition Basins for Navigation Channel Management in Small Craft Inlets

“…Operational requirements necessitate maintenance of the navigational channel both in the inlet throat and the channel extending offshore. Consequently, with advances in computational efficiencies, process-based models are now routinely used to characterize existing inlet morphodynamics (e.g., Elias and Hansen 2013;Reyes-Merlo et al 2017;Petti et al 2020) and evaluate potential inlet management solutions (e.g., Shaeri et al 2017;Fernández-Fernández et al 2019;Zarzuelo et al 2019) for both the inlet throat and offshore channel. However, studies are most often associated with either larger commercial channels, open coast, or highly energetic inlets.…”