Underground Reservoirs (Aquifers): Types, Formation, and Importance

An aquifer is a permeable rock/sediment layer holding groundwater. Water originates from precipitation seeping underground.

Types

1. Unconfined Aquifer: Water table open to atmosphere; recharged by precipitation; accessed via wells.
2. Confined Aquifer: Water trapped between impermeable layers; under pressure; may flow upward when drilled.
3. Artesian Aquifer: Confined aquifer with enough pressure to flow above ground without pumps.
4. Perched Aquifer: Small, localized aquifer separated from main system by impermeable layer; often in hilly areas.

Aquifers are vital freshwater sources for drinking, agriculture, industry. Over-extraction causes depletion, subsidence. Sustainable management is essential.