Payments for Ecosystem Services: Reverse-Auction Simulator (2D)

Payments for Ecosystem Services (PES) programs pay landowners to keep land forested instead of converting it to agriculture, because the water filtration, flood attenuation, and carbon storage that forest provides is worth more to society than it costs to compensate the owner. This simulator models a 400-parcel watershed as a reverse auction: every parcel carries its own private opportunity cost drawn from a log-normal distribution, and as you raise the per-hectare payment rate, parcels enroll in ascending order of cost — exactly like real programs such as Costa Rica's PSA or the US Conservation Reserve Program. This 2D top-down view shows each parcel's cost as square size and its enrollment state as color, with a faint blue tint marking upslope ridge parcels, while live readouts track enrolled area, program cost, total ecosystem service value, net social benefit, and a flood-risk index that falls as upslope forest cover grows. Drag to pan the grid and scroll to zoom in on any parcel.