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Tripartite Agreement (Trepartsaftalen, 2021)

What it is

The Danish Tripartite Agreement (Trepartsaftalen) was a 2021 political agreement between the Danish government and agricultural/environmental stakeholders. It set binding minimum areas for specific nature and environmental measures that must be implemented regardless of whether they are cost-effective for water quality targets.

In TargetEcon, the Tripartite Agreement is encoded as six hard-constraint area floors.

The six floors

Measure Area floor Constraint name Scope
LRl — Lavbund retirement ≥ 51,000 ha Lavbund_eq Nationwide
FO — Forestation ≥ 28,000 ha Afforestation_eq Catchments with N targets
WL — Wetlands ≥ 7,500 ha Wetland_eq Catchments with N targets
MW — Mini-wetlands ≥ 40,000 ha equivalent MW_eq Catchments with N targets
LRh — High-land retirement ≥ 17,700 ha LRH_eq Catchments with N targets
SA — Set aside ≥ 84,000 ha SA_eq Catchments with N targets

Total non-water-quality land-use change mandated: approximately 232,200 ha (before overlap). This is a very large area — for context, Denmark has ~2.6 million ha of agricultural land.

Model implementation

Lavbund_eq..      Σ PotV(i,"LRL") × x(i,"LRL") + exceed_lav ≥ 51,000
Afforestation_eq.. Σ_k$(n_targets>0) Σ_i PotV(i,"FO") × x(i,"FO") ≥ 28,000
Wetland_eq..      Σ_k$(n_targets>0) Σ_i PotV(i,"WL") × x(i,"WL") ≥ 7,500
MW_eq..           Σ_k$(n_targets>0) [Σ MW areas] ≥ 40,000
LRH_eq..          Σ_k$(n_targets>0) Σ_i PotV(i,"LRH") × x(i,"LRH") ≥ 17,700
SA_eq..           Σ_k$(n_targets>0) Σ_i PotV(i,"SA") × x(i,"SA") ≥ 84,000

exceed_lav and exceed_MW are penalty variables (both with Penalty1) allowing the constraints to be technically infeasible if the physical potential is insufficient, while still driving the model toward meeting them as far as possible.

Interaction with water quality optimization

The Tripartite constraints force the model to implement measures that may be sub-optimal for water quality cost-effectiveness. Key interactions:

  • SA (84,000 ha) is by far the largest floor. SA is an N measure but may not be the most cost-effective one — the constraint forces it regardless, which can significantly increase total cost.
  • LRl (51,000 ha) is a nationwide floor. Since lavbund land tends to be in catchments with high N loading, this measure is often selected by the cost-minimizing model anyway — but the floor ensures it happens even in marginal cases.
  • Scenarios without the tripartite constraints (setting all these constraints to inactive) give the pure cost-effectiveness optimum — useful for computing the "price" of the Tripartite Agreement.

Scenario implications

A common scenario type: with vs. without tripartite constraints — comparing total cost and measure mix. This quantifies the "additional cost" of the political agreement beyond pure water quality cost-effectiveness.

Open questions

  1. Is the "SA ≥ 84,000 ha" floor for a specific type of set aside (e.g. permanent, or temporary), or all set aside?
  2. Are the Tripartite floors based on new implementation in VP3, or total stock (including VP2)?
  3. Is there any flexibility in these floors (e.g. trading off SA area against LRh area)?
  • VP2 & VP3
  • WFD — legal backdrop for water quality targets that the tripartite measures support
  • Constraints
  • SA — largest floor (≥84,000 ha); spatially differentiated N effect
  • LRl — lavbund floor (≥51,000 ha); nationwide scope
  • WL — wetland floor (≥7,500 ha); NR retention measure
  • FO — afforestation floor (≥28,000 ha); includes subsidy offset
  • LRh — high-land retirement floor (≥17,700 ha); TR retention
  • MW — mini-wetland floor (≥40,000 ha equivalent)