Ground water

                                          GROUND WATER

• Water which occurs below the surface of earth occupying pores and other opening in the rock  this  is called ground water or subsurface water. or underground water.
• Sources of ground water --- a) meteoric water  (rain water)  b) connate water  ( water  inert rapped in sediment ) c) juvenile water.(magmatic water)
• Upper surface of zone of saturation is called Water Table.
• Rocks in which water can flow easily are called pervious rocks. e.g. sand stone, conglomerate.( sedimentary rock)
• Rocks in which water cannot flow easily are called impervious rocks.  e.g.  Shale, non porous rocks,( Igneous rocks, metamorphic rocks ) massive, free from joints if joints are not open, fine grained.
• Rain water disposed in 3 ways. 1) evaporates 2) run off 3) percolates into ground.
• Water table below the surface is controlled by texture & structure of rock.
• Capable of holding water & easily flow is called Aquifer.
• Hold some of quantity of water but does not flow is called Aquiclude.
• Depth zones of ground water :-On the basis of ground water occurrence and movement at least two major zones can be recognized

1)    Zone of Aeration- or zone of vadose water ( zone of non saturation)

Soil water zone or gravity water zone or perched water zone or capillary water zone

At the surface is the zone of aeration. This is never completely filled with water but water is percolating through this zone. Ground water in this zone is under downward movement due to gravity. Water in this zone is under no

hydrostatic head except temporarily.

2)    Zone of saturation-

Below the aeration zone comes the zone of saturation. The top of this zone is the water table. But the water table rises in the wet weather and sinks in the dry season .The result is that immediately below the zone of aeration there is zone in which rocks are saturated only in the wet season when the water table rises and are left dry when the water table falls in dry season. This is called zone of intermittent saturation. This extends from highest level reached by the water table after wet weather to the lowest level to which it falls in dry weather.

which extends Blow this comes zone of permanent saturation downward to the limit below which ground water is not found .Below a certain depth because of load of above lying rock there are no openings in rocks for water to occupy and groundwater cannot occurs below this depth. Ground water cannot occur below 1000 m. depth.