Virtually every flood-prone municipality owns physical assets -- streets, sidewalks, parks, walking trails -- that can become infrastructure to reduce flood damage.
Example: As a condition of zoning approval, the developer of a new office building may be required to reconstruct the public sidewalk adjacent to the former construction site.
Instead pouring a typical eight inches of concrete, the developer is required by the municipality to use “new” technology: dome-shaped plastic forms that the construction crew covers with concrete to create the new sidewalk.
Underneath the resulting sidewalk, the domed chambers become voids that capture water from heavy rain. The voids store the excess water until the combined storm-sanitary sewer is able to accept it.
Some of the voids house new trees; the earth in the tree wells filters flood water before it enters the combined sewer.
In short, the municipality — at the developer's cost — has gained a capacious cistern that reduces street flooding at the site and helps relieve the overall burden on the community’s sewer system. (And — win-win — the developer has reduced its outlay for construction material.)