One of the factors influencing the change in water table is the effective porosity, ne, of the zone in which the water table fluctuations occur. ne changes as the depth of water table changes, especially for water tables less than 3 meters depth. Moreover, it should be noted that if the water drops, part of the water is retained by the soil particles; if it rises, air can be trapped in the interstices that are filling with water. Hence ne for rising water i.e., in general, is less than that for a falling water table. The above equation considers only one aquifer system and does not account for inter flows between the aquifers in a multi aquifer system.