Wetlands buffer floods more cheaply than engineered flood control.

Evidence

In a 1960 study of the value of open space, for example, botanist William Niering defended wetlands as “the basic component in a natural system of flood control.” With just a 6-inch rise in level, a 10-acre marsh could store 1,500,000 gallons of water. In a heavy rainstorm, therefore, a wetland acted as a reservoir protecting cities and suburbs downstream. Yet a wetland required no money to construct and very little to maintain. To demonstrate the practical benefits of wetland preservation, Niering told a story about the devastating floods of 1955: In eastern Pennsylvania, the torrents washed out hundreds of bridges, but two bridges survived, and both were just downstream of the Cranberry Bog preserve. — Adam Rome, The Bulldozer in the Countryside, 645

Categorization

• XREF: Ecosystem-services-as-freshwater-infrastructure logic echoes the trees-as-infrastructure essay — nature providing a costly built function for free is a core environmental-justice/civil-engineering bridge. — connects to: Federal flood engineers chose to buy wetlands instead of building reservoirs. — Adam Rome, The Bulldozer in the Countryside:…, 646; Contradictory engineered water management signals the loss of flood equilibrium — Aldo Leopold, A Sand County Almanac: With Other…, 424; Engineers framed preserved wetlands as natural flood-control infrastructure — Adam Rome, The Bulldozer in the Countryside:…, 510
• ADDENDUM: Complements the tree-infrastructure article: both show natural systems performing engineered functions (flood control, air conditioning) at zero construction cost — usable as parallel evidence.