With so many towns and cities built close to rivers, or close to coasts, why do we hear little or nothing about municipalities eyeing land on flood plains for affordable housing?
On one hand, the answer seems obvious. Land on flood plains has always been affordable for good reason. It floods.
Trailer parks, one form of affordable housing, have often been sited on cheap flood plain land. In theory, the housing can be moved in case of flooding. In practice, not so much.1
These days, climate change is playing havoc with rainfall, as well as sea levels and coastal storms. (Climate change deniers may wish to attribute these events to the Hand of God, or cyclical goofy weather, or some other collection of coincidental phenomena. No matter. The flooding events are happening, whatever the cause.)
Major hurricanes have caused serious flooding in the American south in recent years. We’ve just started into 2019 and already a significant rainfall has inundated swaths of the the mid-west, with spring melt still to come.
(The floods over the past year have degraded a significant portion of U.S. defence infrastructure, while Pentagon funds are being diverted to build a wall along the U.S. southern border. But that’s another story.)
A story in Governing, reeking of good sense, questions why we continue to build homes in flood-prone areas, particularly when conventionally-built houses are so prone to expensive repair if they suffer even minor water damage. Read more here: Building Homes in Flood Zones: Why Does This Bad Idea Keep Happening?
The solution for building housing on floodplains is ancient practice around the world: use stilts to elevate the housing above potential flooding.
In America, the practice of elevating is moving beyond a recommended good idea to become regulated by governments from local through to national. Read more about a single example in The Sandwich Enterprise: Tiny Sandwich Beach Cottage To Be Replaced By Taller Home
We might expect the desirability of beachfront properties to absorb the extra costs of raising a house. But as the Risky Waters article linked above explains, developers are still building coastal and beachfront properties without flood protection.
There is no question, however, that if flooding persists, elevating existing housing is an enormously expensive proposition. Read more in CITYLAB: The House of the Future Is Elevated
Still, when it comes to building new structures, or replacement ones, the cost of elevating is not necessarily a huge inconvenience, or even a tremendous cost. Even the military is prepared to consider it.2
Indeed, the structural costs of perching even large buildings on stilts make it a reasonable solution for issues that have nothing to do with flooding.3
So let us end this conversation on flood plains, the way we began it. There is no future in elevating existing housing built on a floodplain. It is, and will continue to be, extraordinarily expensive (not to mention complex) to put it on stilts.
But that’s not the case for new housing, whether a single family dwelling, or a larger one with multiple units. With a preference for free market purchase of land if at all possible, why are municipalities not taking more advantage of floodplains and building affordable housing on stilts?
Footnotes
- For an up-to-date example, see in Jordan Independent: Jordan authorities work on second ice dam on Sand Creek
- You can dig an example out of the following article in Stars & Stripes: Military bases in Nebraska battle flooding as Offutt AFB, Camp Ashland remain under water
- Read more at the BBC: Bristol apartments on stilts to be built over car park
