Random Thought on Density and Water Runoff

I just randomly had a thought a couple of days ago: couldn't, potentially, urbanization allow for a decrease in the amount of water wasted as runoff?

Yes, urban buildings, especially as built currently, greatly reduce the amount of water allowed to recharge into underground aquifers; this water instead ends up on rooftops to evaporate, or runs off pavement, directly into streams and watercourses, maybe even causing preventable erosion. Suburban environments, those that emphasize the automobile, with large streets, and parking lots everywhere, are very bad, too.

But what if all urban buildings, or even just a majority of them, were built with "green roofs"? This could enhance the position of the urban, denser environment in respect to the suburban, as all building roofs could potentially replace at least part of the water collection role that the ground those buildings cover played, whereas suburban "sprawl" seems doomed to waste water away. I cannot see any way for parking lots to be "greened up" like roofs can, as cars still need to drive across them; is there any way to do so?

Just a thought.


  1. They actually have grids that you can put down over a lawn that are strong enough for emergency vehicles to drive on, but have large hexagonal holes to allow grass to grow.

    This is such a product although I don't endorse them or anything. Just gives you an idea.

  2. Well, except that parking product isn't intended for full-time parking lots. The grass would surely die.

    No comment on the green roofs idea, but it sounds decent to me...

  3. I feel like with Austin's sometimes torrential rains you might get more than you bargained for. Flash floods are not uncommon and I can just imagine a roof flash flood. That being said, impermeable surfaces are a big issue.

  4. Tim, that's an interesting idea, but it still does not solve the issue, as that's a temporary fix.

    Kevin, thanks. As you say, over the long-term, the grass would most likely die.

    pt, thats quite the point you make. Austin is the center of "Flash-Flood Alley" in the Hill Country. I do though, think that green roofs could be part of the solution to the problem of over-coverage of the soil. There has to be someway to engineer a green roof to be able to dump large amounts of water, but till be cleaner than pure runoff, in torrential downpours.

  5. I think green roofs are just as much if not more likely on midrises or even suburban developments - there's a strong argument for being not too far off the ground with the green roof.

  6. m1ek, I wasn't definitely thinking of high-rise buildings with green roofs, but more of a situation where the density could be like Paris or Washington, D.C., and every building have a green roof. I can definitely understand the height argument.


You're invited to comment on my blogging!