A $40 Million Seawall or a Wetland: A Coastal Town's Adaptation Choice
A coastal town of 18,000 residents must choose among three climate-adaptation projects with a $40 million budget. The town's economy depends on summer tourism, and 30 percent of residents are over 65. The regional hospital sits two blocks from the beach. Projections show 0.6 meters of sea-level rise by 2100 and more frequent storm surge. Option A is a seawall costing $38 million; it would protect about 70 percent of beachfront property for 30 years but could accelerate erosion at the ends of the wall. Option B is managed retreat costing $35 million to buy out 400 homes and restore dunes; it would reduce long-term risk but displace roughly 1,000 residents. Option C is wetland restoration costing $12 million; it would cut surge height by about 20 percent and create habitat but would not protect the hospital. A federal grant requires a benefit-cost ratio above 1.2. The council must also consider that the hospital cannot easily relocate and that the tourism industry depends on the beach.
1. Compare the three options using at least two criteria that matter to this town. Explain why a simple cost ranking is insufficient.
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Using cost alone, wetland restoration looks best at $12 million, but cost does not measure what the town most needs. A second criterion is protection of critical infrastructure: the hospital sits two blocks from the beach, and only the seawall would protect it, though at $38 million and with possible erosion at the wall's ends. A third criterion is equity and displacement: managed retreat reduces long-term risk but moves about 1,000 residents, many of whom may be older or tied to tourism work. Wetland restoration is cheap and ecologically useful, but a 20 percent surge reduction does not protect the hospital. A simple cost ranking therefore ignores lives, hospital access, and who bears the burden. The council needs multi-criteria comparison, not a single dollar figure.
2. Identify two pieces of missing information that could change the council's decision and explain how each would matter.
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First, maintenance and replacement costs over 30 years are missing. A $38 million seawall may need repairs after storms, and a $12 million wetland needs monitoring; if the seawall's true 30-year cost exceeds the grant's benefit-cost threshold, its ranking changes. Second, the council lacks a detailed map of who lives in the 400 buyout homes and whether affordable housing exists nearby. If many residents are elderly or low-income, managed retreat could create a serious equity problem that a benefit-cost ratio does not capture. Other useful data include the hospital's flood-proofing options and the tourism industry's dependence on beach width, since a seawall may narrow the beach. Each piece matters because it tests whether the option that looks efficient also protects the town's most vulnerable residents and core services.
3. Recommend one option or combination and justify it with reference to the town's constraints.
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A defensible recommendation is a hybrid: fund wetland restoration at $12 million, use part of the remaining $28 million for targeted buyouts of the most exposed households, and spend the rest on flood-proofing the hospital and improving evacuation routes. This fits the $40 million budget. The wetland provides surge reduction and habitat at low cost, targeted buyouts avoid the blanket displacement of the $35 million retreat plan, and hospital flood-proofing addresses the weakness that wetland restoration alone leaves. The seawall protects more property, but its $38 million cost leaves almost nothing for the hospital, erosion, or equity measures. The hybrid is not perfect: it protects fewer beachfront homes than the seawall. But it distributes risk reduction across the town's most important constraints rather than concentrating it on property.