Depressed parking refers to parking with grooves in the surface.
These grooves serve two purposes: first to prevent channel flow of
stormwater by keeping runoff distributed across the parking lot
surface and secondly to direct runoff to stormwater mitigation
techniques both within and surrounding the parking area.
This strategy is by no means new and is already in place at many
AF Bases; but not on parking lots. Grooved concrete was originally
implemented on runways in order to improve traction for aircrafts
during wet conditions. Parking lots, roads and a variety of other
applications now utilize depressed or grooved parking.