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Scenario: P_only

Policy question

What is the cost of meeting VP3 phosphorus targets alone, with Tripartite Agreement floors? Isolates the P component and reveals which measures drive P cost-effectiveness.

Parameters

var_N = 0   // N targets OFF
var_P = 1
var_B = 0
var_C = 0
// Tripartite constraints: ACTIVE

Key results

Indicator Value
Total cost (mDKK/yr)
P reduction achieved (kg P/yr)
Lake catchments with unmet P targets
Dominant P measures
Stream measures selected

Derived insight

Cost(Baseline_NP) − Cost(P_only) = marginal cost of also meeting N targets. Compare with Baseline_NP − N_only to understand the asymmetry: does meeting N while doing P cost the same as meeting P while doing N?

Notes

  • P-only scenario will likely select: NPB20, PPC, stream measures (re-meandering, ochre traps), P wetlands.
  • Tripartite floors (especially SA and LRl) impose N-type land-use changes even when only P is targeted — these contribute to cost without benefiting P targets directly, unless SA/LRl have coincidental P effects (SA has none; LRl P = 0).
  • This scenario highlights the cost of the tripartite floors for P-only policy: the floors force large-scale land conversion that doesn't help P targets.