44
3 An ERA Acute Model Overview
Table 3.2 Lag-times in shoreline types classified by energy level and main oil characteristics
Shoreline
energy status
(ESI)
t lag (years)
Type 1 very
light oils
Type 2 light
oils
Type 3
medium oils
Type 4 heavy
oils
High energy
(ESI 1A-2B)
–
0
0
0
0
Medium
energy (ESI
3A-7)
0–1
0
0
1
1
Low energy
(ESI 8A-10E)
3–10
0
3
7
10
The restoration phase is defined as the period from when oiling is below the effect
threshold value until vegetation and invertebrates have reached 99% of the pre-spill
function. Recovery rates for shorelines after damage by oiling for modelling purposes
have been reviewed in detail by French-McCay (2009). Assumed values of time to
recovery (t rec ) for vegetation or species important for the structure of a habitat, are
specific to habitat type and are based on experiences from observations of natural
recovery following disturbance (including spills) and from habitat creation projects.
Time for recovery of benthic invertebrates to 99% of function/pre-spill situation is
shown in table Table 3.3 (Brude et al. 2015).
RDF SH is calculated using the generic calculation for each ESI ranking. The unit
is “kilometeryears”. Usually no distinction is possible between lag and restoration
Table 3.3 Restoration -times
in shoreline
types—vegetation and
invertebrate communities
(time to 99% of pre-spill
function)
Habitat type (ESI
class)
Vegetation or
structure (years)
Invertebrates
(years)
Rocky shore (1 and 8)
Exposed rocky
platforms (2)
Fine grained sand
beaches (3)
Coarse grained sand
beaches (4)
Mixed sand and gravel
beaches (5)
Gravel beaches and rip
rap-structures (6)
Exposed tidal flats (7
and 9)
–
3
Wetland: Emergent
Marsh (10A, 10B)
15
5
Wetland: Swamp (10C,
10D)
20
5
3 An ERA Acute Model Overview
Table 3.2 Lag-times in shoreline types classified by energy level and main oil characteristics
Shoreline
energy status
(ESI)
t lag (years)
Type 1 very
light oils
Type 2 light
oils
Type 3
medium oils
Type 4 heavy
oils
High energy
(ESI 1A-2B)
–
0
0
0
0
Medium
energy (ESI
3A-7)
0–1
0
0
1
1
Low energy
(ESI 8A-10E)
3–10
0
3
7
10
The restoration phase is defined as the period from when oiling is below the effect
threshold value until vegetation and invertebrates have reached 99% of the pre-spill
function. Recovery rates for shorelines after damage by oiling for modelling purposes
have been reviewed in detail by French-McCay (2009). Assumed values of time to
recovery (t rec ) for vegetation or species important for the structure of a habitat, are
specific to habitat type and are based on experiences from observations of natural
recovery following disturbance (including spills) and from habitat creation projects.
Time for recovery of benthic invertebrates to 99% of function/pre-spill situation is
shown in table Table 3.3 (Brude et al. 2015).
RDF SH is calculated using the generic calculation for each ESI ranking. The unit
is “kilometeryears”. Usually no distinction is possible between lag and restoration
Table 3.3 Restoration -times
in shoreline
types—vegetation and
invertebrate communities
(time to 99% of pre-spill
function)
Habitat type (ESI
class)
Vegetation or
structure (years)
Invertebrates
(years)
Rocky shore (1 and 8)
Exposed rocky
platforms (2)
Fine grained sand
beaches (3)
Coarse grained sand
beaches (4)
Mixed sand and gravel
beaches (5)
Gravel beaches and rip
rap-structures (6)
Exposed tidal flats (7
and 9)
–
3
Wetland: Emergent
Marsh (10A, 10B)
15
5
Wetland: Swamp (10C,
10D)
20
5