The phrase "impermeable surfaces" refers to surfaces that cannot let liquids or gases pass through them. They are like barriers that do not allow anything to go through. Full definition
We know that flooding is already a problem in many parts of Southern Florida and that the rise of population, loss of mangroves and wetlands, and spread of impermeable surfaces will only make it worse. (vox.com)
In 2008, the city passed a stormwater ordinance requiring new developments and redevelopments to capture the first half inch of runoff or reduce impermeable surfaces by 15 percent. (scientificamerican.com)
Other property owners can help by taking it easy on the fertilizer and resisting the urge to install impermeable surfaces like concrete. (nrdc.org)