The value of permeable paving became clear over the weekend when we had a series of intense thunderstorms. Out walking yesterday I saw several good sized ponds on asphalted driveways, as well as deltas of dirt and sand where runoff washed away parts of exposed soil.
Where asphalt had been replaced by brick or interlocking blocks, though, I saw no standing water. Water had been able to percolate into the soil, replenishing both the ground water and cutting down on run-off.
The walkways and parking places reminded me of the gorgeous paving mosaics I saw in Lisbon in May. While maintenance of such widespread use of small-block paving is easier where labour is cheap, a lot can be said for it even in North America. Repairs do not require breaking up a large swath of paving, since just the blocks affected can be replaced. And since our freeze and thaw cycle means that asphalt or concrete paving is going to break up after a few years anyway, why not start out with something that will move with the frost cycle without major damage?
The pictures are of several sorts of mosaics that I saw, from the most basic on ordinary, residential streets to the gorgeous designs on Avenida da Liberdade.