Marshall Shepherd on how roads and roofs help cause urban floods
Heavy rains we're not the only cause of recent urban flooding, according to University of Georgia research meteorologist
Marshall Shepherd. His June 2010 study also blames what he calls ‘impervious
cover’ – that is, roofs, streets, and sidewalks – for the disastrous floods in Atlanta in 2009 and Nashville and Oklahoma City in 2010.
Marshall Shepherd: What we found with the Atlanta floods, and indeed many of the recent floods in 2010, is that it was a perfect convergence
of several meteorological factors. But one of the other interesting aspects of this flooding event is the real signature of the impervious surfaces of the urban land cover.
Impervious surfaces, like roofs of buildings, sidewalks and parking lots, don’t absorb the rainwater the way soil does. The water runs off.
Marshall Shepherd: Coupled with
um streams and lakes that were already nearing capacity in terms of soil moisture, when you dump a lot of rainfall on urban impervious surfaces, it runs off in volumes quite rapidly. And it really had nowhere to go.
Dr. Shepherd said that humans are playing a bigger role than before in creating conditions that are ripe for floods in cities.
Marshall Shepherd: What we're clearly seeing is that the role of human beings and their impervious surface is as much a part of the hydrological
water cycle system in cities as the natural environment itself.These are really hand in hand.