Numerical simulation of the propagation of ship-induced Riemann waves of depression into the Venice Lagoon

Abstract

Large in situ measured ship-induced depression waves (Bernoulli wakes) in the Malamocco-Marghera industrial channel of the Venice Lagoon are interpreted as long-living strongly nonlinear Riemann (simple) waves of depression. The properties of these depressions are numerically replicated using nonlinear shallow water theory and the CLAWPACK software. The further behaviour of measured depressions is analysed by means of replicating the vessel-induced disturbances with the propagation of initially smooth free waves. It is demonstrated that vessel-driven depressions of substantial height (> 0.3 m) often propagate for more than 1 km from the navigation channel into areas of the lagoon of approximately 2 m water depth. As a depression wave propagates into the lagoon, its front slope becomes gradually less steep, but the rear slope preserves an extremely steep bore-like appearance and the amplitude becomes almost independent of the initial properties of the disturbance. Analysis suggests that even modest ships in terms of their size, sailing speed, and blocking coefficient may generate deep depressions that travel as compact and steep entities resembling asymmetric solitary waves over substantial distances into shallow water adjacent to navigation channels. Their impact may substantially increase the environmental impact of ship wakes in this and similar water bodies.

Fast shoreline erosion induced by ship wakes in a coastal lagoon: Field evidence and remote sensing analysis

“…If navigation channels cross shallow lagoons, these wakes can propagate far into the adjacent shallow-water areas as highly non-linear asymmetric waves [ 23 ] with a steep rear face. Such entities often induce intense turbulence over a range of several hundreds of meters from the channel, with potentially high impact on the morphology of marginal areas [ 29 ].…”

“…The aim of the investigation is to evaluate the relative importance of erosion induced by ship traffic in the general context of morphological changes that occurred in the central Lagoon of Venice. Besides the specific problem of Venice and its port, understanding the effects of navigation in confined channels surrounded by shallow water areas [ 23 , 29 ] may be of help in addressing technical solutions for similar situations worldwide, improving criteria for environmental decision making and sustainable management of ecosystem services.…”

Depression Waves Generated by Large Ships in the Venice Lagoon

“…The potential impact of depression waves propagating as strongly nonlinear Riemann waves across wide and shallow shoals has been demonstrated by Parnell et al (2015) and Rodin et al (2015). Provided that their amplitude is large enough to ensure a strongly nonlinear regime of propagation, waves generated in a narrow channel constructed in a shallow lagoon may penetrate to substantial distances.…”

“…The far-field impact of depression waves generated in such channels has been demonstrated (Rapaglia et al, 2011(Rapaglia et al, , 2014Parnell et al, 2015;Rodin et al, 2015) and their further propagation has been acceptably replicated in the strongly nonlinear framework of Riemann waves . However, the physics of their generation is yet to be clarified.…”

Cruise Shipping and Urban Development

“…In areas like lagoons, which are protected from sea waves and winds, their effects are much more important than in the open sea. Several studies conducted in the Venetian Lagoon have shown that ships, especially large ones create significant depression waves (Rapaglia et al, 2011(Rapaglia et al, , 2015Parnell et al, 2015;Rodin et al, 2015;Gelinas et al, 2013). They can reach up to 2.5 metres in vertical displacement and can propagate up to 500 metres away from canals to shallow areas (Parnell et al, 2015).…”