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Scenario: No_tripartite

Policy question

What is the minimum cost of meeting VP3 N and P targets if the Tripartite Agreement area floors are removed? This is the pure cost-effectiveness benchmark for water quality — the model's unconstrained optimum for meeting environmental targets.

Parameters

var_N = 1
var_P = 1
var_B = 0
var_C = 0
// Tripartite constraints: ALL INACTIVE (comment out or set targets to 0)
//   Lavbund_eq:      INACTIVE
//   Afforestation_eq: INACTIVE
//   Wetland_eq:      INACTIVE
//   MW_eq:           INACTIVE
//   LRH_eq:          INACTIVE
//   SA_eq:           INACTIVE

Key results

Indicator Value
Total cost (mDKK/yr)
N reduction achieved (tons N/yr)
P reduction achieved (kg P/yr)
Dominant measures selected
SA area selected (ha)
LRl area selected (ha)
FO area selected (ha)

Derived insight — The cost of the Tripartite Agreement

Cost of Tripartite Agreement = Cost(Baseline_NP) − Cost(No_tripartite)
This is the key policy number: how many additional DKK per year does Denmark pay because of the political area floors, above what purely water quality cost-effectiveness would require?

Notes

  • Without the SA floor (84,000 ha), SA is unlikely to be selected at large scale — it is generally less cost-effective than CCS or N10.
  • Without the LRl floor (51,000 ha), LRl may still be selected in low-retention catchments where its NR advantage and field-specific leaching make it attractive.
  • FO may still be selected even without the 28,000 ha floor, particularly where the land value annuity (Adj_Ann_Jordv_2pro) makes its net cost very low or negative.
  • The measure mix shift relative to Baseline_NP directly shows which tripartite measures the model "doesn't want" from a pure water quality perspective.

Implementation note

To deactivate tripartite constraints, the cleanest approach is either: - Comment out the six equations in the model - Or set their RHS to 0 (floor of 0 ha = effectively inactive) The exceed_lav and exceed_MW penalty variables should also be set to 0 to avoid spurious cost contributions.

  • Baseline_NP — with tripartite floors → the difference is the political cost
  • N_only_no_tripartite — N only, no floors → pure N efficiency frontier