An aquifer may be made to serve as a filter plant when artificial recharge is made to pass through an intervening layer of rock, which acts as a natural filter.

Aquiclude is to be treated as a practically impermeable rock mass. Compacted clay formation are best example of aquicludes.

The intermediate vadose zone occurs immediately below zone of soil water. It is in fact a zone of non-saturation: water in this zone is moving downwards under influence of gravity.

Sedimentary rocks are relatively porous because re is a great variation in degree of packing on one hand and in size, shape and arrangement of grains on or hand.

The groundwater is relatively much safe from hazards of chemical, radiogenic and biological pollution to which surface water bodies are badly exposed.

In all igneous rocks, surface zone when highly weared and disintegrated may become quite porous and permeable and hence water-bearing.

Gravels are classed among best kind of formations to yield groundwater. But se too show a great variation in ir water bearing properties depending on degree of assortment, packing and cementing of grains.

Gravels, limestones and sandstones generally form good aquifers when occurring in suitable geological conditions and geographic situations.

The root system of crops in water-logged areas gets decomposed. Large areas of land in Indian subcontinent are affected by water-logging.

In unconfined aquifer, upper surface of water or water-table is under atmospheric pressure which may be acting through interstices in overlying rocks.