Building roofs and parking lots cause prevent rain from naturally entering the ground. A bird's eye view of a building shows a footprint where water can not drain into the ground and must drain into non-footprint areas. Other objects such as tiled patios can effectively increase the footprint of roofs and parking lots.
A larger 'object footprint' reduces the area for natural draining.
What is the correct term for 'object footprint', which prevents natural draining and its complement: land that permits natural draining of water?