Geoscience Reference
In-Depth Information
Tamar case study
The River Tamar is a small river flowing southwards across the south-western
peninsula of England and separating the counties of Devon and Cornwall.
Within the catchment, diffuse nitrate pollution from agriculture is a problem
and was chosen as the issue to be addressed in this case study application of
the DSS.
The management measures selected for representation within the DSS were
realistic and reflect previous and ongoing management interventions to address
diffuse pollution in the catchment:
reduction in fertilizer applications and improved fertilizer practices
●
reduction in stocking density
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shift from arable to pasture
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restoration of wetlands
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Decision criteria were then chosen that could be used to assess the conditions of
the sub-catchments under different scenarios of the application of these measures.
The decision criteria were:
nitrate concentration at the outlet of each of the major sub-catchments:
yearly average and summer average (as this is an ecologically sensitive
period)
●
costs of implementing the measures
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biodiversity indicators: area of non-farmed land and area of wetland
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hydrological parameters: mean flow, high flow (Q5) and low flow (Q95)
●
Three different management options were selected for the application, differing
in the extent to which each of the management measures outlined above are
applied. These scenarios were:
Business as Usual (BAU) - Current management and development policies
continue unchanged
●
Policy Targets (PT) - Policy targets are achieved. This is a 'moderately green'
strategy
●
Deep Green (DG) - Restoration of the catchment and sustainability are
management priority
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The climate change scenario years 2050 and 2085 and IPCC climate scenarios A2
and B2 were chosen for use in this exercise. The A2 scenario is characterized by
increasing global population, a move towards self-reliance at the national scale
and regionally orientated economic development. The B2 scenario is characterized
by increasing population, but at a lower level than A2, with a greater emphasis
on sustainable development at a local level. When overlaid on the three
management options, therefore, there are in total 12 climate/management
combinations. For comparison, the current conditions are included as a climate/
management combination, making a total of 13.
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