Fast Ferry Traffic as a Qualitatively New Forcing Factor of Environmental Processes in Non-Tidal Sea Areas: A Case Study in Tallinn Bay, Baltic Sea

Abstract

The impact of wake wash from high-speed ferries on the coastal environment in non-tidal seas is analysed in terms of wave energy and power, and properties of the largest waves. Shown is that hydrodynamic loads caused by heavy high-speed traffic may play a decisive role not only in low-energy coasts but also in certain areas with high wind wave activity. For example, ship-generated waves form, at least, about 5-8% from the total wave energy and about 18-35% from the wave power in the coastal areas of Tallinn Bay exposed to dominating winds. The periods of wake waves from high-speed ships frequently are much larger than dominating periods of wind waves. The leading waves typically have a height of about 1 m and a period of 10-15 s. Such waves extremely seldom occur in natural conditions in many regions of semi-enclosed seas. They cause unusually high hydrodynamic loads in the deeper part of the nearshore. The fast ferry traffic thus is a qualitatively new forcing component of vital impact on the local ecosystem. It is demonstrated that wakes from high-speed ferries may trigger considerable changes of the existing balance of coastal processes. Owing to their low decay rates combined with their exceptional compactness after crossing many kilometres of the sea surface, such wakes may cause considerable remote impact of the ship traffic. This feature has to be addressed in the analysis of the impact of harbours and associated ship traffic in the neighbourhood of vulnerable areas.

Temporal scales of water-level fluctuations in lakes and their ecological implications

“…Often, the latter are not considered in the context of WLF, although they can have a major impact on the abiotic and biotic processes in the littoral zone. Several studies have investigated the impact of short-term WLF on coastal and shelf regions (Clark, 1997;Eriksson et al, 2004;Soomere, 2005;Erm & Soomere, 2006). Only a few investigations, however, have focused on lake-littoral zones (Luettich et al, 1990;Eggleton et al, 2004;Scheifhacken, 2006).…”

The Failure of Fast Ferry Catamaran Operations in New Zealand and Hawaii

“…Particularly fast ferries show a high ratio of propulsion power to vessel displacement as it is a precondition for reaching high speeds. This, together with near-critical and supercritical speeds, leads to high loads on the coastal environment [39]. This has been confirmed in a series of studies conducted at Tallinn Bay, Estonia [37,39,[42][43][44].…”

“…The massive growth in exhaust emissions per passenger-mile and the great increase in external noise and waves generated by large high-speed ships are the major concerns of environmental studies [37][38][39]. Additionally, environmental impact studies on fast ferries have found that, whereas hull shape have little effect on resistance or wash, water depth [40] and the displacement/length ratio have a significant effect.…”

Ship-induced solitary Riemann waves of depression in Venice Lagoon

“…It is commonly believed that the largest environmental impacts come from long and long-crested almost nondispersive wave groups of significant amplitude [6,7]. Another recognized hazard is caused by solitonic waves that may result in high water velocities [8], elevate water levels at the shore [9] or build rogue waves [10].…”