11 Applications of an Oil Drift and Fate Model for Fairway Design
373
with suspended matter and others. See Dick and Soetje (1990), Børresen (1993),
Reed et al. (1999) for a comprehensive review.
Oil spills are most efficiently combated at sea, before any shoreline is polluted.
If weather conditions are favourable, barricades may be set up to contain the spill,
and oil is collected (skimmed and pumped) from the sea surface or combated chemically (Fingas 2011). At the coast, conditions for combating are usually less perfect,
and a major, lengthy, labour-expensive and costly clean-up operation, with usually
doubtful results, is commonly at hand even if the amount of spilled oil is moderate
(Bi et al. 2011). In nearshore waters, prevailing weather conditions (first of all the
direction of wind and waves) and the distance from spill site to shore, decide which
scenario (open water or coast) unfolds.
For offshore accidents the third major player is the system of currents and the
fourth—the time. Minor spills disperse into the open waters, provided enough time
passes before the bulk of the spill reaches the nearshore. Even this process is not
without consequences. For example, in semi-enclosed seas like the Baltic Sea the
cumulative effects of small spills have been detected as a systematic increase in the
background hydrocarbon concentration (Pikkarainen and Lemponen 2005). Still at
a moderate level, this diffusive pollution is considered less harmful than soiling the
ecologically sensitive shoreline.
11.2.2 Oil Drift
Oil spill modelling has been an extremely valuable tool for the management of and
combating with oil pollution (Fingas 2011) as well as a key contributer to the relevant decision-making process for about thirty years (Reed et al. 1999). A standard
oil drift model produces information on the oil’s location, slick size, spreading, composition, and drift either in a hindcast mode for past events or, more importantly,
forecasts these parameters and properties for some time in the nearest future based
on the available or forecast metocean information (e.g., Janeiro et al. 2012). It is
normally used as an operational stand-by tool, to be activated in case of an incident.
An emergency drift calculation is performed in real time, tracking a spill that has
taken place at a given point at a certain time instant, or within a limited span in time
and space, using available information on the actual and future weather and ocean
conditions. Preventive measures can then be taken at sea, weather, wave and ocean
current (met-ocean) conditions permitting.
An oil drift model estimates the evolution in time and space of a hypothetic
or a real oil spill. Given a set of initial conditions describing the spill itself (time
and location of release, magnitude, duration, oil type), and present and upcoming
metocean conditions, a suite of information about the oil spill (called spill state
vector) is updated using a time stepping algorithm and using certain equations and
relationships governing the oil spill evolution. The state vector contains all timedependent physical and chemical information required for the next step forward in
time to be evaluated similarly to the process of solving of any differential equation
373
with suspended matter and others. See Dick and Soetje (1990), Børresen (1993),
Reed et al. (1999) for a comprehensive review.
Oil spills are most efficiently combated at sea, before any shoreline is polluted.
If weather conditions are favourable, barricades may be set up to contain the spill,
and oil is collected (skimmed and pumped) from the sea surface or combated chemically (Fingas 2011). At the coast, conditions for combating are usually less perfect,
and a major, lengthy, labour-expensive and costly clean-up operation, with usually
doubtful results, is commonly at hand even if the amount of spilled oil is moderate
(Bi et al. 2011). In nearshore waters, prevailing weather conditions (first of all the
direction of wind and waves) and the distance from spill site to shore, decide which
scenario (open water or coast) unfolds.
For offshore accidents the third major player is the system of currents and the
fourth—the time. Minor spills disperse into the open waters, provided enough time
passes before the bulk of the spill reaches the nearshore. Even this process is not
without consequences. For example, in semi-enclosed seas like the Baltic Sea the
cumulative effects of small spills have been detected as a systematic increase in the
background hydrocarbon concentration (Pikkarainen and Lemponen 2005). Still at
a moderate level, this diffusive pollution is considered less harmful than soiling the
ecologically sensitive shoreline.
11.2.2 Oil Drift
Oil spill modelling has been an extremely valuable tool for the management of and
combating with oil pollution (Fingas 2011) as well as a key contributer to the relevant decision-making process for about thirty years (Reed et al. 1999). A standard
oil drift model produces information on the oil’s location, slick size, spreading, composition, and drift either in a hindcast mode for past events or, more importantly,
forecasts these parameters and properties for some time in the nearest future based
on the available or forecast metocean information (e.g., Janeiro et al. 2012). It is
normally used as an operational stand-by tool, to be activated in case of an incident.
An emergency drift calculation is performed in real time, tracking a spill that has
taken place at a given point at a certain time instant, or within a limited span in time
and space, using available information on the actual and future weather and ocean
conditions. Preventive measures can then be taken at sea, weather, wave and ocean
current (met-ocean) conditions permitting.
An oil drift model estimates the evolution in time and space of a hypothetic
or a real oil spill. Given a set of initial conditions describing the spill itself (time
and location of release, magnitude, duration, oil type), and present and upcoming
metocean conditions, a suite of information about the oil spill (called spill state
vector) is updated using a time stepping algorithm and using certain equations and
relationships governing the oil spill evolution. The state vector contains all timedependent physical and chemical information required for the next step forward in
time to be evaluated similarly to the process of solving of any differential equation