Definition

Ground water is the underground water that occurs in the saturated zone of variable thickness and depth, below the earth’s surface. Cracks and pores in the existing rocks and unconsolidated crystal layers, make up a large underground reservoir, where part of precipitation is stored.

Ground water resource

1. Ground water is largely tapped for irrigation crops in India. So much so that about 46% of our total irrigated area, gets its irrigation from this source. Most of our minor irrigation scheme, make use of this source of supply. Besides its use for irrigation, ground water is also used as a source of water supply for municipal purposes.
2. The main source of ground water is precipitation. A portion of rain falling on earth’s surface infiltrates into ground, travels down and, when checked by impervious layer to travel further down, forms ground water.
3. The ground water reservoirs consist of water held in voids within a geological stratum. Other sources of ground water include water from deep in the earth which is carried upward in intrusive rocks and water which is trapped in sedimentary rocks during their formation.
4. The quantities of such water are small and they are often so highly mineralised as to be unsuited for use. Water bearing formation of the earth’s crust act as conduits for transmission and as reservoirs of storage of ground water.
5. The discharge from ground water occurs in two ways: (1) natural way, (2) artificial way. The natural discharge occurs in lakes, reservoirs, rivers, oceans and springs. Pumpage from the wells constitutes the major artificial discharge from ground water.