More housing ≠ more flooding
Should drainage be a private or public responsibility?
Flooding has always been one of the big excuses not to build denser forms of housing in Austin.
There is a certain intuitive logic to it. The more land that is taken up by concrete, the less ground is left to absorb rainfall. And in Austin, a property that is zoned single-family can only be 45% impervious cover, while those zoned for multifamily housing have much higher allowances.
The thing is, if you want to reduce impervious cover citywide, the solution is build even more densely. Look at a downtown skyscraper. Imagine how much more land would be covered with cement if all of those units were spread out over a single-story development. On a much smaller scale, the best way to reduce impervious cover in a single-family neighborhood is to allow or encourage people to build higher –– a three-story 2,000 sq ft home creates less impervious cover than a one-story home of that size.
The problem is that those who are most concerned about impervious cover are even more hostile to the prospect of taller buildings. So they're not interested in altering regulations that restrict height, such as limits on Floor to Area Ratio (FAR).
The other thing about flooding is that it's not just about impervious cover. It has more to do with drainage infrastructure. Staff from the Watershed Protection Department sought to make this clear during the last two failed efforts to overhaul the land development code.
