Ship-induced solitary Riemann waves of depression in Venice Lagoon

Parnell, Kevin E.; Soomere, Tarmo; Zaggia, Luca; Rodin, Artem; Lorenzetti, Giuliano; Rapaglia, John; Scarpa, Gian Marco

doi:10.1016/j.physleta.2014.12.004

Cited by 31 publications

(52 citation statements)

References 31 publications

(41 reference statements)

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“…Bridges & Leeder, ; Choi et al ., , ). Although boat traffic in the Venice Lagoon could contribute to destabilizing the bar brink zone (Parnell et al., ; Rapaglia et al., ), the occurrence of detachment surfaces in bar deposits dates back to a few centuries ago (i.e. before the onset of boat traffic), thus suggesting that these processes commonly occur in natural systems and are not triggered by human influence.…”

Section: Discussionmentioning

confidence: 99%

Tidal currents and wind waves controlling sediment distribution in a subtidal point bar of the Venice Lagoon (Italy)

et al. 2019

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The present study aims to improve current understanding of the sedimentation of subtidal point bars, analyzing interaction between tidal currents and waves in shaping a submerged meander bend of the microtidal Venice Lagoon (Italy), and it is based on coupling of sedimentological studies, geophysical analyses and numerical modelling. The Venice Lagoon is characterized by an average depth of about 1Á5 m over subtidal platforms and a mean tidal range of about 1Á0 m. The morphodynamic evolution of the lagoon is strongly affected by intense seasonal windstorms, which promote the formation of wind waves triggering sediment resuspension and bottom erosion. The study channel is 70 to 100 m wide, it has a radius of curvature of about 260 m and cuts through a permanently submerged subtidal platform. Water depth ranges from 1Á0 to 5Á0 m below mean sea level on the subtidal platform and channel thalweg, respectively. Different from classical architectural models, the study point-bar beds do not show sigmoidal geometries, but consist of horizontally-bedded deposits abruptly overlying clinostratified beds. Sedimentation in the study bar is hypothesized to stem from the interaction between the in-channel secondary helical flow, as for most meander bends, and wave winnowing of the subaqueous overbank areas. Laterally accreting point-bar deposits point out that the curvature-induced helical flow redistributed sediment from the channel thalweg to the bar top and contributed to the development of the 'classical' fining-upward grain size trend. The marked truncation surface, separating clinostratified bar deposits from overlying horizontally-bedded platform sediments is interpreted here as due to bar top wave-winnowing, which also possibly promoted bank collapses. In the proposed model, sediments remobilized from bar top and subaqueous overbank areas were transported into the channel, forming peculiar 'apronlike' accumulations, where sand accumulated through avalanching processes and mud settled down from suspension.

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Section: Discussionmentioning

confidence: 99%

Tidal currents and wind waves controlling sediment distribution in a subtidal point bar of the Venice Lagoon (Italy)

et al. 2019

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“…Virtually all records showed the development of a step on the rear slope of the depression wave. Parnell et al (2015) show that these waves are described reasonably well as long-living strongly nonlinear solitary Riemann depression waves. At those sites where water speeds were also recorded (B1, B2, W1 and W2), even small depression waves generated high near bed speeds (greater than 0.65 m/s in the examples shown).…”

Section: Resultsmentioning

confidence: 79%

“…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.…”

Section: Discussionmentioning

confidence: 99%

“…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.…”

Section: Discussionmentioning

confidence: 99%

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Depression Waves Generated by Large Ships in the Venice Lagoon

Parnell

Zaggia

Soomere

et al. 2016

Journal of Coastal Research

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At present cruise ships use the Lido and Giudecca channels to berth at the Port of Venice, and cargo vessels use the Malamocco-Marghera channel to berth at the Marghera industrial area. Following a government decree to restrict large ship access to the Port of Venice through the Lido and Giudecca channels, the Port authority has been investigating the construction of a new channel between Marghera and the cruise terminal, to re-route all large vessels through the Malamocco lagoon entrance. Ships in the Venice Lagoon travel at low speeds with associated low depth-based Froude numbers (<0.5), and classical Kelvin wave effects are minimal. However, under certain channel geometries, depression waves (also known as Bernoulli wake) can be substantial with significant far-field effects. In the Malamocco-Marghera Channel, depression waves up to 2.5 m, with high (~1.5 m/s) near bed water speeds, transform into asymmetric Riemann waves, able to propagate large distances from the navigation channel into the shallow lagoon. By contrast, depression waves associated with large ships in the Lido and Giudecca channels are much smaller (~0.3-0.4 m). Rerouting large cruise ships entering the Port of Venice through the MalamoccoMarghera channel and a newly constructed channel will have adverse effects on the Venice lagoon with increased water velocities and sediment resuspension associated with the nonlinear Riemann waves. It is therefore essential that the potential effects be thoroughly evaluated using an appropriate methodology before the development of a new lagoon channel.

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“…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).…”

Section: Waves and Vibrationsmentioning

confidence: 99%

Cruise Shipping and Urban Development

Itf¹

2016

International Transport Forum Policy Papers

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Ship-induced solitary Riemann waves of depression in Venice Lagoon

Cited by 31 publications

References 31 publications

Tidal currents and wind waves controlling sediment distribution in a subtidal point bar of the Venice Lagoon (Italy)

Tidal currents and wind waves controlling sediment distribution in a subtidal point bar of the Venice Lagoon (Italy)

Depression Waves Generated by Large Ships in the Venice Lagoon

Cruise Shipping and Urban Development

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