Paving paradise: the peril of impervious surfaces

Paved surfaces are among the most ubiquitous of man-made structures. When rain falls upon pavements and other impervious surfaces, it has nowhere else to go except into the nearest waterway, carrying with it a wide variety of potentially harmful substances. This pollution can affect animal (and potentially human) populations and taint waters used for recreation and drinking. Impervious surfaces also increase the likelihood of serious flooding, impair groundwater recharge, and compound the "urban heat island" effect. Research is under way on new porous surfaces that allow water to percolate down to the ground beneath. These materials are proving to be as durable as their traditional countertparts. Municipalities are also looking at other methods of controlling runoff that use constructed green spaces and waterways to capture water and help eliminate some of the problems associated with high-density paving.