Sand dune breaching along the Emilia-Romagna Littoral zone:a deterministic approach

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Marco Miani, Pushpa Dissanayake, Renata Archetti, Alberto Lamberti

Friday 3 july 2015

9:30 - 9:45h at Antarctica (level 0)

Themes: (T) Sediment management and morphodynamics, (ST) Morphodynamics of estuaries and coastal areas

Parallel session: 14A. Sediment - Coast

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Extreme met-ocean conditions cause proportioned wave run-up and load on sand dunes which potentially trigger the formation of a fast growing dune breach leading to coastal flooding. The objective of this study is to investigate deterministically how and to what extent waves trigger and drive breaching of sand dunes. The selected study area is Emilia-Romagna (Italy) where these processes were investigated in detail with focus on wave impact, when lateral erosion (alongshore) occurs leading to breaching of the dune systems. Spatial and temporal high-resolution numerical simulations using the XBeach morphological model were carried out to study wave run up, overtopping and breaching of sand dunes along a representative reach of Emilia-Romagna coastal dunes. Unlike previous studies, XBeach was set up in 2D mode using the built-in non-hydrostatic module in order to model the dispersive waves with high accuracy. This allows to investigate the alongshore evolution of the breach, triggered by wave run-up on the seaward slope. Run-up values obtained with XBeach are consistent with results od SWASH simulations used for comparison. Validation against experimental data, for run-up and discharge rates, is under preparation.