324
T. Soomere
10.2.1 Quantification of Environmental Risks
A commonly used measure is the probability of the valuable areas being hit by pollution. It is straightforward to associate with each offshore point the probability of
oil propagation from this site to a certain vulnerable area. Its sensible use implicitly requires the setting of a (propagation) time scale over which this probability is
counted (Andrejev et al. 2010; Viikmäe et al. 2010). Doing so naturally leads to a
complementary quantity that can equally well characterize the potential of pollution released at a particular sea point to pose danger to the nearshore: the average
time it takes for the pollution to reach the valuable area. This measure is similar to
commonly used water age (Deleersnijder et al. 2001) and is called particle age in
the following discussion. It naturally characterizes the cost of consequences from
another viewpoint: the longer time pollution remains in the open sea, the larger
fraction of it will be weathered or may be removed before it hits a vulnerable spot.
These measures are of course not equivalent. The values of particle age intrinsically contain information about whether the particle had reached the vulnerable
area. A hit to a valuable area obviously has occurred if the age of a particle is less
than the propagation time. Therefore it is straightforward to evaluate the probability
of hits to the vulnerable areas once the values of the age of all particles are known.
An inversion of this operation is not possible because the values of probability only
contain information about whether or not a hit has occurred.
The quantification is performed in this chapter in the context of the propagation
of oil pollution from different offshore areas to the nearshore. It is obviously applicable for any adverse impact that is passively carried by surface currents. Its possibilities are demonstrated for relatively simple particular cases of constant-value coast.
These examples are rich enough in content to highlight not only the complexity of
the problem but also the variety of solutions depending on a particular set-up and intrinsic uncertainties of the technology. Accounting for the more complicated internal
structure of the high-value areas is also straightforward. For example, it is possible
to identify certain locations from where the oil is less likely to be transported to selected vulnerable spots of any kind (e.g., marine protected areas, Delpeche-Ellmann
and Soomere 2013), or from where the transport will take a longer time (Viikmäe
and Soomere 2013).
10.2.2 Preventive Optimization of Dangerous Activities
Once a map of the probabilities of hitting a specific area (or particle age) has been
constructed, the optimum locations for potentially dangerous activities (areas of reduced risk) are the minima for the probabilities or the maxima for the particle age.
The obvious practical outcome is the possibility to plan (or redirect) dangerous activities into such areas. These maps are, however, of much larger practical importance. They may serve as the basis for various engineering solutions, decision support systems and preventive methods for the environmental management of shipping
T. Soomere
10.2.1 Quantification of Environmental Risks
A commonly used measure is the probability of the valuable areas being hit by pollution. It is straightforward to associate with each offshore point the probability of
oil propagation from this site to a certain vulnerable area. Its sensible use implicitly requires the setting of a (propagation) time scale over which this probability is
counted (Andrejev et al. 2010; Viikmäe et al. 2010). Doing so naturally leads to a
complementary quantity that can equally well characterize the potential of pollution released at a particular sea point to pose danger to the nearshore: the average
time it takes for the pollution to reach the valuable area. This measure is similar to
commonly used water age (Deleersnijder et al. 2001) and is called particle age in
the following discussion. It naturally characterizes the cost of consequences from
another viewpoint: the longer time pollution remains in the open sea, the larger
fraction of it will be weathered or may be removed before it hits a vulnerable spot.
These measures are of course not equivalent. The values of particle age intrinsically contain information about whether the particle had reached the vulnerable
area. A hit to a valuable area obviously has occurred if the age of a particle is less
than the propagation time. Therefore it is straightforward to evaluate the probability
of hits to the vulnerable areas once the values of the age of all particles are known.
An inversion of this operation is not possible because the values of probability only
contain information about whether or not a hit has occurred.
The quantification is performed in this chapter in the context of the propagation
of oil pollution from different offshore areas to the nearshore. It is obviously applicable for any adverse impact that is passively carried by surface currents. Its possibilities are demonstrated for relatively simple particular cases of constant-value coast.
These examples are rich enough in content to highlight not only the complexity of
the problem but also the variety of solutions depending on a particular set-up and intrinsic uncertainties of the technology. Accounting for the more complicated internal
structure of the high-value areas is also straightforward. For example, it is possible
to identify certain locations from where the oil is less likely to be transported to selected vulnerable spots of any kind (e.g., marine protected areas, Delpeche-Ellmann
and Soomere 2013), or from where the transport will take a longer time (Viikmäe
and Soomere 2013).
10.2.2 Preventive Optimization of Dangerous Activities
Once a map of the probabilities of hitting a specific area (or particle age) has been
constructed, the optimum locations for potentially dangerous activities (areas of reduced risk) are the minima for the probabilities or the maxima for the particle age.
The obvious practical outcome is the possibility to plan (or redirect) dangerous activities into such areas. These maps are, however, of much larger practical importance. They may serve as the basis for various engineering solutions, decision support systems and preventive methods for the environmental management of shipping