1 Towards Mitigation of Environmental Risks
17
societies’ rules is mainly prescriptive, without any transparent link to an overall
safety objective. The IMO has developed guidelines for the use of the formal safety
assessment methodology 7 in rule development, which will provide risk-based goaloriented regulations.
Another example is the use of the gradually adopted first-principle-based approaches in design that can provide—with the help of structural reliability analysis—more detailed failure probabilities than those represented by ship accident
databases. Still sufficient information is necessary about the physical and statistical
models of the ocean environment and related uncertainties. Thus, one of the major
challenges (partially addressed in this book) consists in the further development of
methods and technology for the use of this type of information in solving dynamical
problems.
An intrinsic property of the statistical approach is that the outcome only expresses certain significant features of the underlying pool of data. In other words,
the use of such an outcome provides a clear benefit if a large pool of cases is considered while for single particular cases the damage can still be substantial. However,
this approach is one of the few feasible ways to reach an approximate solution to
the inverse problem of pollution propagation as discussed below.
1.11 Favourable Patterns of Currents and Current-Induced
Transport
As discussed above, a key prerequisite for the reduction of risk for ship traffic is the
existence of certain favourable patterns in the sea domain in question. In the abovediscussed case of the fairway to Boston Harbour (Stokstad 2009) such a pattern
became available in the density of the presence of whales. In principle, any similar
favourable pattern, including patterns of currents or current-induced transport, may
be used for similar purposes. The line of thinking here is the same as for the use of
jet currents saving some fuel, finding sea areas with lower waves and decreasing the
risk of wave damage, or for systems of currents transporting potential pollution to
less vulnerable sea areas (Soomere and Quak 2007).
The most impressive and well-known patterns in the dynamics of the World
Ocean are persistent currents such as the Gulf Stream, Kuroshio, Agulhas or many
coastal currents. Their potential in the reduction of coastal pollution is similar to
the impact of wind and waves: the safest location is the one that is located maximally upstream from the vulnerable domain. Further progress in the practical use
of current patterns has recently been achieved because of major findings in semienclosed sea areas. Namely, certain sea areas (in which the systems of currents were
previously believed to be highly stochastic and practically impossible to forecast)
were shown to possess persistent patterns of mesoscale currents at certain depths
on a multi-year scale (Andrejev et al. 2004). In addition, semi-persistent patterns of
7 http://www.safedor.org/resources/1023-MEPC392.pdf.
17
societies’ rules is mainly prescriptive, without any transparent link to an overall
safety objective. The IMO has developed guidelines for the use of the formal safety
assessment methodology 7 in rule development, which will provide risk-based goaloriented regulations.
Another example is the use of the gradually adopted first-principle-based approaches in design that can provide—with the help of structural reliability analysis—more detailed failure probabilities than those represented by ship accident
databases. Still sufficient information is necessary about the physical and statistical
models of the ocean environment and related uncertainties. Thus, one of the major
challenges (partially addressed in this book) consists in the further development of
methods and technology for the use of this type of information in solving dynamical
problems.
An intrinsic property of the statistical approach is that the outcome only expresses certain significant features of the underlying pool of data. In other words,
the use of such an outcome provides a clear benefit if a large pool of cases is considered while for single particular cases the damage can still be substantial. However,
this approach is one of the few feasible ways to reach an approximate solution to
the inverse problem of pollution propagation as discussed below.
1.11 Favourable Patterns of Currents and Current-Induced
Transport
As discussed above, a key prerequisite for the reduction of risk for ship traffic is the
existence of certain favourable patterns in the sea domain in question. In the abovediscussed case of the fairway to Boston Harbour (Stokstad 2009) such a pattern
became available in the density of the presence of whales. In principle, any similar
favourable pattern, including patterns of currents or current-induced transport, may
be used for similar purposes. The line of thinking here is the same as for the use of
jet currents saving some fuel, finding sea areas with lower waves and decreasing the
risk of wave damage, or for systems of currents transporting potential pollution to
less vulnerable sea areas (Soomere and Quak 2007).
The most impressive and well-known patterns in the dynamics of the World
Ocean are persistent currents such as the Gulf Stream, Kuroshio, Agulhas or many
coastal currents. Their potential in the reduction of coastal pollution is similar to
the impact of wind and waves: the safest location is the one that is located maximally upstream from the vulnerable domain. Further progress in the practical use
of current patterns has recently been achieved because of major findings in semienclosed sea areas. Namely, certain sea areas (in which the systems of currents were
previously believed to be highly stochastic and practically impossible to forecast)
were shown to possess persistent patterns of mesoscale currents at certain depths
on a multi-year scale (Andrejev et al. 2004). In addition, semi-persistent patterns of
7 http://www.safedor.org/resources/1023-MEPC392.pdf.