3.4 Shoreline Compartment
45
phases in recovery studies from spills (as in French-McCay 2009), meaning that
implementation of observed recovery times as restoration time in ERA Acute can be
conservative when including also a lag-time before recovery can start.
RDF SH ,SF =
Imp r,month × t imp
2
+ (Imp r,month × t lag ) +
Imp r,month × t res
2
(3.9)
• t imp : Impact time. Time until full impact is observed. This value is set to 1 year as
most acute impacts are assumed to be apparent after 1 reproductive year cycle.
• t lag : Lag-time. Time until contamination has been reduced sufficiently for
restoration to begin.
• t res: Restoration time. The time from restoration starts until the population/community is restored to a pre-defined level of its pre-spill status or equivalent
threshold.
• Imp is impacted length of coastline (km).
3.5 Water Column Compartment
3.5.1 Impact Modelling
Two different approaches are developed for ERA Acute water column impact
calculations and are described in the development report by Brönner et al. (2015).
3.5.1.1 Time-Averaged THC-Max
One alternative calculation uses input of “THC max ” (total hydrocarbon concentration)
from the oil drift simulations to calculate p let in each cell, using an SSD curve
(Nilsen et al. 2006). In OSCAR, this representative THC-concentration is calculated
throughout the oil drift simulations, the highest THC-concentration from any of the
water layers is recorded at each time-step and the final value is the average of these
(time-averaged “THC max ”). Similar values from other reliable oil spill models may
also be used, however differences in how the inputs are calculated must be observed.
The concentration is entered into a dose-response curve (Species Sensitivity
Distribution (SSD)) proposed by Nilsen et al. (2006) for use in EIF Acute (Spikkerud
et al. 2006). The SSD is based on a dataset compiled by the National Research Council
of the National Academies (2005).
The SSD curve has a 5% effect level (LC5) of 58 ppb THC for dispersed oil in
sensitive species, and a LC50 value of 193 ppb. p let in each simulation and each grid
cell i is given as:
p let,W C,i,sim = Φ
lnx − ln193)
0.73
, μ, σ
(3.10)
45
phases in recovery studies from spills (as in French-McCay 2009), meaning that
implementation of observed recovery times as restoration time in ERA Acute can be
conservative when including also a lag-time before recovery can start.
RDF SH ,SF =
Imp r,month × t imp
2
+ (Imp r,month × t lag ) +
Imp r,month × t res
2
(3.9)
• t imp : Impact time. Time until full impact is observed. This value is set to 1 year as
most acute impacts are assumed to be apparent after 1 reproductive year cycle.
• t lag : Lag-time. Time until contamination has been reduced sufficiently for
restoration to begin.
• t res: Restoration time. The time from restoration starts until the population/community is restored to a pre-defined level of its pre-spill status or equivalent
threshold.
• Imp is impacted length of coastline (km).
3.5 Water Column Compartment
3.5.1 Impact Modelling
Two different approaches are developed for ERA Acute water column impact
calculations and are described in the development report by Brönner et al. (2015).
3.5.1.1 Time-Averaged THC-Max
One alternative calculation uses input of “THC max ” (total hydrocarbon concentration)
from the oil drift simulations to calculate p let in each cell, using an SSD curve
(Nilsen et al. 2006). In OSCAR, this representative THC-concentration is calculated
throughout the oil drift simulations, the highest THC-concentration from any of the
water layers is recorded at each time-step and the final value is the average of these
(time-averaged “THC max ”). Similar values from other reliable oil spill models may
also be used, however differences in how the inputs are calculated must be observed.
The concentration is entered into a dose-response curve (Species Sensitivity
Distribution (SSD)) proposed by Nilsen et al. (2006) for use in EIF Acute (Spikkerud
et al. 2006). The SSD is based on a dataset compiled by the National Research Council
of the National Academies (2005).
The SSD curve has a 5% effect level (LC5) of 58 ppb THC for dispersed oil in
sensitive species, and a LC50 value of 193 ppb. p let in each simulation and each grid
cell i is given as:
p let,W C,i,sim = Φ
lnx − ln193)
0.73
, μ, σ
(3.10)