11 Applications of an Oil Drift and Fate Model for Fairway Design
389
vection in the northern region of the gulf. As a result, the spatial patterns of the
probability and residence time are reversed compared to their appearance in winter
and summer. Whereas the summer and winter patterns show relatively low values
(<30 %) for the probability of oil landing in the northern regions of the Gulf of
Finland, the corresponding spring and autumn patterns reveal maximum values of
more than 50 % in this domain (Fig. 11.5). A broad band of low probabilities for
coastal landing (<20 %) extends along the Estonian coast that is located upwind
from the sea in these seasons.
The spatial distributions of the average oil residence time mirror the analogous
distribution for the landing probabilities. In particular, the distribution of the residence time for summer/winter and for the transitional seasons are almost exactly
reversed with respect to each other. Namely, oil in areas where if released in summer and winter, it spent a long times at sea, exhibits generally faster coastal landing
in autumn and spring (Fig. 11.6). Almost everywhere along the southern (Estonian)
coast of the gulf the released oil spills spend more than 4 days at sea before they hit
the coast whereas at the northern (Finnish) and north-eastern (Russian) coast the oil
resides less than 2 days at sea. Therefore, in winter and summer there will be, on
average, about 3 days more time than in the transitional seasons to combat the potential oil pollution released near the Finnish coast. Correspondingly, about 3 extra
days will be available for oil combating in winter and summer off the Estonian coast.
The performed drift pattern analysis results in a set of distinct maps that are
suitable for fairway design similarly to the efforts described in Chap. 10. There is
always a dilemma of which map to choose as probably no unambiguous measure
of the environmental benefit of employing one of the two results can be defined.
Moreover, there are certain ambiguities in the patterns that arise from frequently
changing wind conditions. The two distinct and substantially different patterns for
the summer-winter (SW) and spring-autumn (SA) seasons seem to be quite stable
over the 3 years of the modelled period. From the 36 months in total, 18 months
feature the SW pattern and 15 months the SA pattern. No distinct pattern seems to
exist during the remaining three months. As none of these SW and SA drift patterns
seems to be dominant or significantly overlapping enough to form the background
for fairway design decisions, a smart decision would be to design different optimum
fairways for different seasons.
11.5 Fairway Design
Fairways are usually designed to comply with topographical conditions, traffic regulations, national and international agreements, and basic economical standards. In
the focus of the design process are the vessel’s operational conditions. Environmental factors (such as atmospheric conditions, wave properties or ocean circulation)
that might considerably influence the travel have so far been of minor importance.
The optimum fairways are usually as short as possible, contain as few straight lines
as possible and involve a minimum number of turns. The obvious reason behind
389
vection in the northern region of the gulf. As a result, the spatial patterns of the
probability and residence time are reversed compared to their appearance in winter
and summer. Whereas the summer and winter patterns show relatively low values
(<30 %) for the probability of oil landing in the northern regions of the Gulf of
Finland, the corresponding spring and autumn patterns reveal maximum values of
more than 50 % in this domain (Fig. 11.5). A broad band of low probabilities for
coastal landing (<20 %) extends along the Estonian coast that is located upwind
from the sea in these seasons.
The spatial distributions of the average oil residence time mirror the analogous
distribution for the landing probabilities. In particular, the distribution of the residence time for summer/winter and for the transitional seasons are almost exactly
reversed with respect to each other. Namely, oil in areas where if released in summer and winter, it spent a long times at sea, exhibits generally faster coastal landing
in autumn and spring (Fig. 11.6). Almost everywhere along the southern (Estonian)
coast of the gulf the released oil spills spend more than 4 days at sea before they hit
the coast whereas at the northern (Finnish) and north-eastern (Russian) coast the oil
resides less than 2 days at sea. Therefore, in winter and summer there will be, on
average, about 3 days more time than in the transitional seasons to combat the potential oil pollution released near the Finnish coast. Correspondingly, about 3 extra
days will be available for oil combating in winter and summer off the Estonian coast.
The performed drift pattern analysis results in a set of distinct maps that are
suitable for fairway design similarly to the efforts described in Chap. 10. There is
always a dilemma of which map to choose as probably no unambiguous measure
of the environmental benefit of employing one of the two results can be defined.
Moreover, there are certain ambiguities in the patterns that arise from frequently
changing wind conditions. The two distinct and substantially different patterns for
the summer-winter (SW) and spring-autumn (SA) seasons seem to be quite stable
over the 3 years of the modelled period. From the 36 months in total, 18 months
feature the SW pattern and 15 months the SA pattern. No distinct pattern seems to
exist during the remaining three months. As none of these SW and SA drift patterns
seems to be dominant or significantly overlapping enough to form the background
for fairway design decisions, a smart decision would be to design different optimum
fairways for different seasons.
11.5 Fairway Design
Fairways are usually designed to comply with topographical conditions, traffic regulations, national and international agreements, and basic economical standards. In
the focus of the design process are the vessel’s operational conditions. Environmental factors (such as atmospheric conditions, wave properties or ocean circulation)
that might considerably influence the travel have so far been of minor importance.
The optimum fairways are usually as short as possible, contain as few straight lines
as possible and involve a minimum number of turns. The obvious reason behind