Physical and numerical modelling of wave transformations in the Venice Lagoon

Aim of the study is to assess the capability of a numerical model to reproduce the wave modification when propagating in a very shallow water environment crossed by small canals. This is a typical situation within the Venice Lagoon, and it does appear that the wave transformation due to the cutting canals can be responsible of bank erosion and of other important phenomena (e.g. reflection and set-up/down). A suitable wave model was therefore applied to the “academic case” of a rectangular trough of finite width, and compared with the results obtained through the laboratory tests, specifically performed in a wave flume. The applied model, SWAN, is an advanced third generation model, specifically developed for shallow waters. The model is based on the wave action balance equation with sources and sinks terms. Being the wave action conserved for a wave propagating in non-homogeneous media, the SWAN model seems to fit the requirements to correctly reproduce the wave evolution over a trough. Once validated with the laboratory data, the wave model could be applied to the convoluted bathymetry of the lagoon and used to get an estimate of the energy dissipation on the canals’ edges and eventually an estimate of the slopes erosion.