Ground water (2)springs

Springs: - Springs are natural out flow of G. W. under favourable structural condition. If water flow at a single point  it is called spring. If along line is called seepage spring is an intersection of the ground with the water table in a particular area. They show great variation in  their mode of occurrence in the quality of water and rate of flow. Springs results under a great variety of structural condition and are broadly classified according to the condition that give rise to them.                                                                                                                                                                                                       

Depression springs  Depression cutting below the water table and such springs are called depression spring.

                                                                     

Contact springs :-Contact springs in which contact of a pervious water bearing layer with an underlying impervious layer is intercepted by a slope .water percolating in the pervious rock can not sink further when it meets the impervious rock below .In Deccan trap area contact spring results on hill sides where compact  jointed basalt is underlain by amygdaloidal basalt.

  Fault springs :- A Fault bringing an impervious rock against a permeable water bearing formation may result in to formation of springs along the fault. Fault zones are favorable for springs .

 Hot springs: - Occurs in areas of active volcano. The water of these springs is 80 - 90 % meteoric water which get heated when it mixes with  juvenile water hot springs changed with mineral matter in solution CaCO_3, silica, deposit it when the water cools ..

Geysers: -Geysers are hot springs from which a column of hot water & steam explosively erupts at interval because water is periodically heated to its boiling point. by magmatic steam that mixes with it.

Conservation of Ground Water:-

1.     Less no of well in the area of low water table.

2.     Withdrawal must be always less than recharge.

3.     Reduce surface runoff increase percolation

4.     Percolation tanks construct to raise W. T.

5.     Recharge well should be made near sources of river.

6.     Construct barrier in river at regular interval.

Water bearing Capacity of Rocks:-

*Sedimentary rocks – porous, pervious, better water bearing

* Igneous & metamorphic rocks- non porous, only in joints if they are wide open & inter connected.

*Water bearing capacity depends on

  1. Degree of cementation, coarse sediments,

  2. Conglomerate, sandstone, good aquifer.

  3. Well cemented sandstone, Quartzite, nonporous.

  4. Jointed compact basalt – may water bearing if joints well wide open & interconnected.

5. Vesicular, Amygdaloidal basalt – massive, unjointed, vesicules are not interconnected, watertight.

6. Marble, Limestone- hold large quantity of water in.

Geological Work of Groundwater: -   It brings about

1.     Decomposition oxygen, carbon dioxide, chemical decomposition along joints, fractures along which G. W. circulates.

2.     Solutions: - G. W. dissolves soluble material Limestone, Marble.

3.     Deposition:- Along the joints , fracture, fault G. W. circulate & deposition of CaCO₃ silicaFe2O3 etc.stalactities, stalagmites, kankar may form due to deposition of  CaCO_3.