Interactive explainer

Funding Continuous Coastal Protection

A coastal protection project can fail even when its owners can collectively afford it, because the funding rule may leave a critical interface unpaid.

Local Financing of Continuous Coastal Protection under Fragmented Ownership · Zach J.L. Lee

Change the rule and remove the funding bottleneck

Choose an example and change payer radius h. At h = 0, an interface may charge only its two neighbouring parcels; each step reaches one parcel farther in both directions.

The group has enough money overall, but the middle interface cannot reach the owners who have it.

h = 0

Widening h changes who may pay while leaving the owners' combined margin unchanged.

Click an interface to inspect its eligible payers. A red bracket identifies a block that cannot be funded; a green bracket shows the tightest block when the rule works.

Enough money overall?Yes · 8 available, 4 needed
Does the current rule work?No · fails at h = 0
Smallest rule that worksh* = 1

What the example shows

The money exists, but this rule cannot reach it.

At h = 0, the middle interface can charge only parcels 2 and 3. They have no available margin against a cost of 2.

Financing and commitment are separate. Even when every interface can be funded, no-build remains an equilibrium. Eliminating it requires a mandate, binding collective contract, or non-performance assessment that changes the payoff from staying out.

Change the numbersEdit parcel margins, interface costs, or external value

Parcels and interfaces

Participation margins ai−20 to 20

A parcel's margin is its value from completion minus the cost of its own segment.

Interface costs κe0 to 20

Value beyond the owners

External value affects whether completion is worthwhile socially. It never changes the owners' private financing test or h*.

See all model diagnosticsTotals, block deficit, minimum radius, and external value
Total margin Σa8
Total interface cost Σκ4
Private surplus Σa − Σκ4
Block deficit Δ at h = 02
Minimum radius h*1
Accounting deficit f*0