Geoscience Reference
In-Depth Information
Table 11.1
Definition of scenarios and management options
Business as
usual for A2
and B2
scenarios
Policy targets
for A2 and B2
scenarios
Deep green for
A2 and B2
scenarios
Current
Fertilizer
applications
Survey of
fertilizer
practice
(Goodlass &
Allin 2004)
Predicted by
CLUAM
Lower of: 20%
reduction on
CLUAM
prediction or
Nitrate
Vulnerable Zone
limits
50% reduction
on CLUAM
prediction
Stocking
density
Calculated
from Defra
(2004)
Predicted by
CLUAM
Lower of: 15%
reduction on
CLUAM
prediction or
Hill Farm
Allowance levels
60% of CLUAM
prediction
Change
landuse from
arable to
pasture
Current
land-use
distribution
calculated from
Defra (2004)
Predicted by
CLUAM
50% reduction
in arable area
predicted by
CLUAM
80% reduction
in arable area
as predicted by
CLUAM
Wetlands
No change on
current
wetland extent.
50% loss on
current
wetland extent
50% of
floodplains
restored
All floodplains
restored (Hogan
et al
. 2001)
Non-farmed
land
Current
land-use
distribution
calculated from
Defra (2004)
Predicted by
CLUAM
50% increase,
or 1% of
catchment area,
whichever is the
larger
100% increase,
or 2% of
catchment area,
whichever is the
larger
sub-catchments. This is primarily because there is a much higher proportion of
cereals predicted under the B2 scenario compared with the A2 scenario by the
CLUAM (0.1% and 42% of the farmed area for A2 and B2 Business as Usual
scenarios, respectively), so encouraging the necessary transition to grassland to
achieve the management targets in the Policy Targets and Deep Green scenarios
is more expensive and reduces the preference for these management options.
This suggests that under a B2 climate scenario, measures other than those
represented in the DSS scenarios should be employed.
Disaggregating the analysis by sub-catchments allows decision makers to target
management measures within the catchment. For instance, presenting the outputs
as in Fig. 11.6 highlights sub-catchments where the management intervention is
of greatest benefit. Under the A2 climate scenario, for instance, the management
measures assessed in the DSS are most effectively applied in the middle reaches
of the catchment.
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