If you look beneath the surface of the landscape, you will find a complex mixture of rock, gravel, sand or finer-grained material that makes up areas where water can be stored in pore spaces. Gravity causes rainwater or melted snow to move down into the empty spaces in between the soil or cracks in the rock. Eventually the water reaches the saturated zone. In the saturated zone all the void spaces are completely filled with water; the water in the …