Infiltration (hydrology)

Infiltration is a process in hydrology (the study of water and how it moves around the Earth) where water seeps into the ground. Imagine water on a sidewalk. It can either flow down the sidewalk like a river, or it can seep down into small cracks in the sidewalk. In the same way, water that's on the surface of the ground (like rainwater) can either flow off the surface like a river or seep down into cracks and holes in the ground. Infiltration is the process of water seeping down into the ground.