Ground Water Year Book - India 2010-11
Category |
Year Book |
State |
All
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District |
All
|
Block |
All
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Year of Issue |
2011 |
Number of Authors |
1 |
Name of Authors |
CGWB |
Keywords |
Hydrogeological Setup of the Country, Ground Water Level Scenario, Hydrogeological Units and their Ground Water Potential, Rainfall Variations, Ground Water Level Scenario, Ground Water Regime in Unconfined Aquifer, Ground Water Resource Availability and Development Status, Chemical Quality of Ground Water in India. |
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The ground water behaviour in the Indian sub-continent is highly complicated due to the occurrence of diversified geological formations with considerable lithological and chronological variations, complex tectonic framework, climatological dissimilarities and various hydrochemical conditions. Studies carried out over the years have revealed that aquifer groups in alluvial / soft rocks even transcend the surface basin boundaries. Broadly two groups of rock formations have been identified depending on characteristically different hydraulics of ground water, Viz. Porous Formations and Fissured Formations. There are 3 major Aquifer System in the Country a) Unconsolidated formations – alluvial; b) Consolidated/semi-consolidated formations - sedimentary, basalts and crystalline rocks; c) Hilly.
Variability in the onset, withdrawal and quantum of rainfall during the monsoon season has profound impacts on water resources, power generation, agriculture, economics and ecosystems in the country. The average annual rainfall is about 122 cm, but it has great spatial variations. The areas on the Western Ghats and the Sub-Himalayan areas in North East and Meghalaya Hills receive heavy rainfall of over 250 cm annually, whereas the Areas of Northern parts of Kashmir and Western Rajasthan receive rainfall less than 40 cm. The rainfall pattern roughly reflects the different climate regimes of the country, which vary from humid in the northeast (about 180 days rainfall in a year), to arid in Rajasthan (20 days rainfall in a year). Ground water levels are being measured by Central Ground Water Board four times a year during January, March/April/ May, August and November. The ground water level and quality monitoring is of particular importance in coastal as well inland saline environment to assess the changes in salt water/fresh water interface as also the gradual quality changes in the fresh ground water regime. This data is used for assessment of ground water resources and changes in the regime consequent to various development and management activities.
Assessment of ‘Dynamic Ground Water Resources of the country is being carried out periodically to assess the annual ground water recharge and utilization and its availability for future use. As part of the assessment, ‘Annual Extractable Ground Water Resource’ as well as ‘Annual Ground Water Extraction are assessed for each assessment unit (block/taluka/mandal/tehsils/firka etc.).
The quality of groundwater is affected in three ways i.e., physical, chemical and bacteriological, although the procedure is very slow and complex to understand. The quality of ground water in the phreatic aquifer depends on the nature of rocks, contact time, circulation and temperature. It is also dependent on the solubility of the minerals present in the rocks. The quality of ground water is also influenced by the excessive use of fertilizers and pesticides for agricultural production and also industrial activity. Ground water due to its long standing with minerals and rocks is generally more mineralized than surface water. This was found to be confirmed largely for water in phreatic zones. The chemical quality of ground water in phreatic zones is also affected by anthropogenic sources at the ground surface, whether it is domestic, agriculture or industrial in nature.