Ground water resources

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INTRODUCTION

Ground water plays a key role in meeting the water needs of various user-sectors in India. With growing awareness, the dependability on ground water as a sustainable resource in nation building reasserts the need for an organization like Central Ground Water Board which is vested with the responsibilities of assessing and managing the ground water resources of the country through ground water management studies, exploration, evaluation and monitoring of ground water regime.

The Dynamic Ground Water Resource of the country has been jointly estimated by State Ground Water Departments and Central Ground Water Board, based on the methodology recommended by Ground Water Estimation Committee-1997 (GEC-97). The Ground Resource was estimated as on March, 2004. The National level report on "Dynamic Ground Water Resources of India" was finalized and approved by the R&D Advisory Committee in its seventh meeting held at New Delhi on 19th August, 2005. As per the report, the Annual Replenishable Ground Water Resource for the entire country is 433 billion cubic metre (bcm), Net Annual Ground Water Availability is estimated as 399 billion cubic metre whereas the Annual ground water draft for irrigation, Domestic & Industrial was 231 billion cubic metre and their Stage of Ground Water Development for the Country as a whole is 58%.

The Annual Replenishable Ground Water Resource is contributed by two major sources – rainfall and other sources that include canal seepage return flow from irrigation, seepage from water bodies and artificial recharge due to water conservation structures. The overall contribution of rainfall to country’s Annual Replenishable Ground Water Resource is 67% and the share of other sources taken together is 33%. The contribution from other sources such as canal seepage, return flow from irrigation, seepage from water bodies etc in annual replenishable resources is more than of 33% in the states of Andhra Pradesh, Delhi, Haryana, Jammu &Kashmir, Jharkhand, Punjab, Tamil Nadu, Uttar Pradesh, Uttaranchal and UT of Pondicherry. Southwest monsoon being the most prevalent contributor of rainfall in the country, about 73% of country’s Annual Replenishable Ground Water Recharge takes place during the Kharif period of cultivation. Keeping 34 bcm for natural discharge, the Net Ground Water Available for utilization for the entire country is 399 bcm. The Annual Ground Water Draft is 231 bcm,out of which 213 bcm is for Irrigation use and 18 bcm for Domestic & Industrial use. An analysis of ground water draft figures indicates that in the states of Chhattisgarh, Delhi, Goa, Himachal Pradesh, Jammu & Kashmir, Jharkhand, Kerala, north eastern states of Manipur, Meghalaya, Mizoram, Nagaland and Tripura, Orissa, Sikkim, and Union Territories of Dadra & Nagar Haveli, Daman & Diu, Lakshadweep and Pondicherry, ground water draft for domestic &industrial purposes are more than 15% which is comparatively higher than the national average of 8%(Table1). In general, the irrigation sector remains the main consumer of ground water (92% of total annual ground water draft for all uses).

Contents

Table1:State-Wise Ground Water Resources Availability, Utilization and Stage of Development,India
Table.png

STAGE OF GROUND WATER DEVELOPMENT

The stage of ground water development for the country as a whole is 58%. The status of ground water development is comparatively high in the states of Delhi, Haryana, Punjab and Rajasthan and UT of Daman & Diu and Pondicherry, where the Stage of Ground Water Development is more than 100%, which implies that in these states the average annual ground water consumption is more than average annual ground water recharge. In the states of Gujarat,Karnataka, Tamil Nadu and Uttar Pradesh the average stage of ground water development is 70% and above. In rest of the states / UT's the stage of ground water development is below 70%.

Source: Ground Water Year Book-2011, CGWB,India

GROUND WATER OCCURRENCE

The ground water behavior 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 hydro-chemical 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.

Porous Formations

Porous formations have been further subdivided into Unconsolidated and Semi – consolidated formations.

Unconsolidated Formations

The areas covered by alluvial sediments of river basins, coastal and deltaic tracts constitute the unconsolidated formations. These are by far the most significant ground water reservoirs for large scale and extensive development.The hydrogeological environment and ground water regime in the Indo-Ganga-Brahmaputra basin indicate the existence of potential aquifers having enormous fresh ground water reserve. Bestowed with high incidence of rainfall and covered by a thick pile of porous sediments, these ground water reservoirs get replenished every year and are being used heavily. In these areas, in addition to the Annual Replenishable Ground Water Resources available in the zone of water level fluctuation (Dynamic Ground Water Resource), there exists a huge ground water reserve in the deeper passive recharge zone below the zone of fluctuation as well as in the deeper confined aquifers which remains largely unexplored as yet. Although the mode of development of ground water is primarily through dug wells, dug cum bore well and cavity wells, thousands of tube wells have been constructed during last few decades.

Semi-Consolidated Formations

The semi-consolidated formations normally occur in narrow valleys or structurally faulted basins. The Gondwanas, Lathis, Tipams, Cuddalore sandstones and their equivalents are the most extensive productive aquifers in this category. Under favorable situations, these formations give rise to free flowing wells. In selected tracts of northeastern India, these water-bearing formations are quite productive. The Upper Gondwanas, which are generally arenaceous, in general, constitute prolific aquifers.

Fissured Formations (Consolidated Formations)

The consolidated formations occupy almost two-thirds of the country. These formations, except vesicular volcanic rocks have negligible primary porosity. From the hydrogeological point of view, fissured rocks are broadly classified into four types viz. Igneous and metamorphic rocks excluding volcanic and carbonate rocks, Volcanic rocks,Consolidated sedimentary rocks and Carbonate rocks.

HYDROGEOLOGICAL UNITS AND THEIR GROUND WATER POTENTIAL

Hydrogeological map of India and the geographical distribution of hydrogeological units along with their Ground water potential are given below(Figure2):

Figure 2
Source: Ground Water Year Book – India 2010-11 by CGWB
Table 2:Ground Water Aquifer System in India
SystemCoverageGround Water Potential
Unconsolidated
formations - alluvial
Indo-Gangetic,Brahmaputra plains Enormous reserves down to 600 m depth.

High rain fall and hence recharge is ensured. Can support

large-scale development through deep tube wells
Coastal AreasReasonably extensive aquifers but risk of saline water intrusion
Part of Desert area– Rajasthan and GujaratScanty rainfall. Negligible recharge. Salinity hazards. Availability at great depths
Consolidated/semi-consolidated formations - sedimentaries, basalts and
crystalline rocks
Peninsular AreasAvailability depends on secondary porosity developed due to weathering,fracturing etc. Scope for GW availability at

shallow depths (20-40 m) in some areas and deeper depths

(100-200 m) in other areas. Varying yields.
HillyHilly statesLow storage capacity due to quick runoff

GROUND WATER LEVEL SCENARIO

Monitoring of ground water regime is an effort to obtain information on ground water levels and chemical quality through representative sampling. The important attributes of ground water regime monitoring are ground water level, ground water quality and temperature. The primary objective of establishing the ground water monitoring network stations is to record the response of ground regime to the natural and anthropogenic stresses of recharge and discharge parameters with reference to geology, climate, physiography, land use pattern and hydrologic characteristics. The natural conditions affecting the regime involve climatic parameters like rainfall,evapotranspiration etc., whereas anthropogenic influences include pumpage from the aquifer, recharge due to irrigation systems and other practices like waste disposal etc.Ground water levels are being measured four times a year during January, April/ May, August and November. The regime monitoring started in the year 1969 by Central Ground Water Board. At present a network of 15640 observation wells (Figure3) located all over the country is being monitored (CGWB Report, 2011). State-wise distribution of observation wells is given in Table3. Ground water samples are collected from these observation wells once a year during the month of April/ May to obtain background information of ground water quality changes on regional scale. The database thus generated forms the basis for planning the ground water development and management programme. 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.

Figure 3: Location of Ground Water Monitoring Wells
Source: Ground Water Year Book – India 2010-11 by CGWB

Table 3:State-wise distribution of the ground water observation wells
S.No.Name of the StateTotal No. of
Observation Wells
(as on 31.03.2010)
States
1Andhra Pradesh981
2Arunachal Pradesh19
3Assam381
4Bihar373
5Chhattisgarh516
6Delhi87
7Goa53
8Gujarat966
9Haryana426
10Himachal Pradesh85
11Jammu & Kashmir206
12Jharkhand208
13Karnataka1499
14Kerala864
15Madhya Pradesh1325
16Maharashtra1496
17Manipur25
18Meghalaya38
19Nagaland17
20Orissa1214
21Punjab261
22Rajasthan1373
23Tamil Nadu906
24Tripura42
25Uttar Pradesh1218
26Uttaranchal44
27West Bengal909
UT's
1Andaman & Nicober63
2Chandigarh16
3Dadra & nagar Haveli10
4Daman & Diu4
5Pondicherry15
Total15,640

GROUND WATER LEVEL SCENARIO

Depth to Water Level – Pre Monsoon (April/May) 2010

Perusal of the ground water level data for the period May 2010 (Figure 4) indicates that in Sub-Himalayan area, north of river Ganges and in the eastern part of the country in the Brahmaputra valley, generally the depth to water level varies from 2-10 meter below ground level (m bgl). In major parts of north-western states (Indus basin), depth to water level generally varies from 10-20 m bgl with pockets of deeper water level of more than 20 m bgl. In the western parts of the country covering the states of Rajasthan and Gujarat deeper water level is recorded in the range of 10-20 m bgl. In western Rajasthan and north Gujarat deeper water level in the range of 20-40 m bgl and > 40 m bgl have also been also recorded. In the west coast water level is generally less than 10 m and in western parts of Maharashtra State in isolated pockets water level in the range of 2-5 m has also been observed. In the east coast i.e. coastal Andhra Pradesh, Tamil Nadu and Orissa, water level in the range of 2-5 m bgl have been recorded. However South-eastern part of West Bengal recorded water level in the range of 5-10 m bgl. In central India water level generally varies between 5-10 m bgl, with patches where deeper water level more than 10 m bgl has been observed. The peninsular part of country generally recorded a water level in the range 5-10 m bgl. In some patches water level ranges from 10-20 m bgl. Isolated patches of water level of 10-20 m bgl and 20-40 m bgl have been observed.Out of total monitored wells 4.36% wells are showing water level less than 2 m bgl, 24.19 % wells are showing water in the 2-5 m depth range, 41.21% wells are showing water level in the depth range of 5-10 m bgl, 22.67% wells are showing water level in the depth range of 10-20 m bgl, 5.48% wells are showing water level in the depth range of 20-40 m bgl and remaining 2.10 % wells are showing water level more than 40 m bgl.

Figure 4
Source: Ground Water Year Book – India 2010-11 by CGWB

Depth to Water Level – Monsoon (August) 2010

A perusal of depth to water level map of India for August 2010 (Figure 5) reveals that that in sub-Himalayan area, north of river Ganges, generally the depth to water level ranges from 0 to 5 meter below ground level. In the eastern part of the country in the Brahmaputra valley water level generally less than 2 m bgl, except in isolated pockets where depth to water level is in the range of 2 to 5 m bgl. However, in upper Assam, isolated pocket of deeper water level, 5-10 m bgl has been observed. In major parts of Indus basin, depth to water level generally ranges from 5-20 m bgl. In the western part of the country covering states of Gujarat and Rajasthan deeper water level is recorded in the range of20-40 m bgl. Relatively deeper water level in the range of 20-40 m bgl and > 40 m bgl has been observed in Rajasthan,Punjab and Haryana and also in central and north Gujarat. In Maharashtra water level recorded is mostly in the range of 2-5 m bgl except western Maharashtra, where water level is generally less than 2 m bgl. In the east coast i.e. coastal Andhra Pradesh and Tamil Nadu, generally the water level ranges between 5-10 m bgl. In Orissa water level generally is less than 2 m bgl with isolated pockets showing water level in the range of 2-5 m bgl. West Bengal recorded water level in the range of 2-5 m bgl except in coastal parts where water level is in the range of 5-10 m bgl. In central India water level generally varies between 2-10 m bgl, except in isolated pockets where water level is more than 10 m bgl.The peninsular part of country generally water level ranges between 5-10 m bgl except in isolated patches where water level is more than 10 m bgl. Isolated patches of deeper water level in the range of 20-40 m bgl have also been observed in various parts of the country. About 28.25% wells have water level less than 2 m bgl. About 29.85% wells have in the depth range of 2-5 m bgl.24.39% wells have water level in the depth range of 5-10 m bgl. 11.98% wells have water level in the depth range of10-20 m bgl. 3.78 wells have water level in the depth range of 20.40 m bgl. Only 1.74 % wells are showing water level more than 40 m bgl.

Figure 5
Source: Ground Water Year Book – India 2010-11 by CGWB

Depth to Water Level – Post Monsoon (November) 2010

Perusal of the ground water level data for the period November 2010 (Figure 6) indicates that in Sub-Himalayan area, north of river Ganges and in the eastern part of the country in the Brahmaputra valley, generally the depth to water level varies from 2-5 meter below ground level ( m bgl). Isolated pockets of shallow water level less than 2 m bgl have also been observed. In major parts of north-western states depth to water level generally ranges from 10-20 m bgl. In the western parts of the country deeper water level is recorded in the depth range of 20-40 m bgl. In North Gujarat, partof Haryana and western Rajasthan water level more than 40 m bgl is recorded. In the west coast water level is generally less than 5 m and in western parts of Maharashtra State isolated pockets of water level less than 2 m has also been observed. In the east coast i.e. coastal Andhra Pradesh and Orissa, shallow water level of less than 2 m have been recorded. In eastern states, water level in general ranges from 2-5 m bgl. However South-eastern part of West Bengal recorded water level in the range of 5-10 m bgl. In central India water level generally varies between 2-5m bgl, except in isolated pockets where water level more than 5 m bgl has been observed. Similarly pockets of shallow water level less than 2 m bgl is also observed along the west coast. The peninsular part of country generally recorded a water level in the range 2-5 m bgl. In some patches water level ranges from 5-10 m bgl.Out of total monitored wells 23.21% wells are showing water level less than m bgl, 34.75 % wells are showing water in the depth range of 2-5 m bgl, 24.7% wells are showing water level in the depth range of 5-10 m bgl, 11.85% wells are showing water level in the depth range of 10-20 m bgl, 3.73% wells are showing water level in the depth range of 20-40 m and remaining 1.76 % wells are showing water level more than 40 m bgl.

Figure 6
Source: Ground Water Year Book – India 2010-11 by CGWB

Depth to Water Level – Post Monsoon (January) 2011

Perusal of the ground water level data for the period January 2011 (Figure 7) indicates that in Sub-Himalayan area, north of river Ganges and in the eastern part of the country in the Brahmaputra valley, generally the depth to water level varies from 2-5 meter below ground level. Isolated pockets of shallow water level less than 2 m bgl have also been observed. In major parts of north-western states depth to water level generally ranges from 10-20 m bgl. In the western parts of the country deeper water level is recorded in the depth range of 20-40 m bgl. In North Gujarat, part of Haryana and western Rajasthan water level more than 40 m bgl is recorded. In the west coast water level is generally less than 5 m and in western parts of Maharashtra State isolated pockets of water level less than 2 m has also been observed. In the east coast i.e. coastal Andhra Pradesh and Orissa, shallow water level of less than 2 m have been recorded. In eastern states, water level in general ranges from 2-5 m bgl. However South-eastern part of West Bengal recorded water level in the range of 10-20 m bgl. In central India water level generally varies between 5-10 m bgl, except in isolated pockets where water level less than 5 m bgl has been observed. Similarly pockets of shallow water level less than 2 m bgl is also observed along the west coast. The peninsular part of country generally recorded a water level in the range 5-10 m bgl. In some patches water level ranges from 10-20 m bgl.Out of total monitored wells 15.35% wells are showing water level less than 2 m bgl, 35.85 % wells are showing water in the depth range of 2-5 m bgl, 30.27% wells are showing water level in the depth range of 5-10 m bgl, 12.96%wells are showing water level in the depth range of 10-20 m bgl, 3.87% wells are showing water level in the depth range of 20-40 m and remaining 1.71 % wells are showing water level more than 40 m bgl.

Figure 7
Source: Ground Water Year Book – India 2010-11 by CGWB

ANNUAL WATER LEVEL FLUCTUATION

Annual Water Level Fluctuation (May 2009-May 2010)

A comparison of depth to water level during May 2010 with May 2009 (Figure 8) reveals that, in general there is fall in water level in various states of India except in parts of the states of Andhra Pradesh, Karnataka, Kerala and Madhya Pradesh where majority of wells analysed showing rise in water level mostly in the range of 0-2 m. The rise in water level in the range of 2-4 m and greater than 4 m is observed only in few pockets in the state of Madhya Pradesh, Karnataka and Maharastra. About 41.40% wells are showing rise in water level. Out of which 32.88% wells are shoring rise in water level less than 2 m range. 5.55% wells are showing rise in water level in 2-4 m range and 2.97% wells showing rise in water level more than 4 m. About 58.60 % wells are showing decline in water level, out of which 44.34% wells are showing decline in water level in less than 2 m range. 8.77% wells are showing decline in water level in 2-4 m range. Only 5.49% wells are showing decline in water level more than 4 m.

Figure 8
Source: Ground Water Year Book – India 2010-11 by CGWB

Annual Water Level Fluctuation (August 2009- August 2010)

A comparison of depth to water level during August 2010 with August 2009 (Figure 9) reveals that in general, there is decline in the water level in eastern part of the country. Most of the wells have been showing fall of water level in the range of 0-2 m and are common in all the eastern states. Rise / fall in water level in the range of 0-2 meters may not be significant in view of dynamic nature of groundwater resources. Fall in water level more than 2 meters on long term basis has also been observed in various parts of the states such as Andhra Pradesh, Delhi, Madhya Pradesh, Uttar Pradesh, eastern Rajasthan, Haryana and Punjab. Rise in water level in the range of 0-2 m and 2-4 m is observed in Central Maharashtra, Andhra Pradesh, Madhya Pradesh and Gujarat states. About 52.6% wells are showing rise in water level. Out of which 38.88% wells are shoring rise in water level less than 2 m range. 8.66% wells are showing rise in water level in 2-4 m range and 5.0% wells showing rise in water level more than 4 m. About 47.45 % wells are showing decline in water level, out of which 37.39% wells are showing decline in water level in less than 2 m range.5.29% wells are showing decline in water level in 2-4 m range. Only 4.44% wells are showing decline in water level more than 4 m.

Figure 9
Source: Ground Water Year Book – India 2010-11 by CGWB

Annual Water Level Fluctuation (November 2009- November 2010)

A comparison of depth to water level during November 2009 with November 2010 (Figure 10) reveals that in general, there is decline in the water level in eastern part of the country. Most of the wells have been showing fall of water level in the range of 0-2 m and are common in all the eastern states. Fall in water level more than 2 meters has also been observed in various parts of the states such as Delhi, Madhya eastern Uttar Pradesh, Bihar, Jharkhand, West Bengaland western Maharashtra, Gujarat state. Rise in water level in the range of 0-2 m and 2-4 m is observed any Central Maharashtra, Andhra Pradesh, southern Rajasthan and Gujarat states. About 57.48% wells are showing rise in water level. Out of which 43.47% wells are shoring rise in water level less than 2 m. About 8.20% wells are showing rise in water level in 2-4 m range and 5.8% wells showing rise in water level more than 4 m. About 42.52 % wells are showing decline in water level, out of which 34.33% wells are showing decline in water level in less than 2 m range.About 5.98% wells are showing decline in water level in 2-4 m range. Only 2.21% wells are showing decline in water level more than 4 m range.

Figure 10
Source: Ground Water Year Book – India 2010-11 by CGWB

Annual Water Level Fluctuation (January 2010- January 2011)

A comparison of depth to water level during January 2010 with January 2011 (Figure 11) reveals that in general, there is decline in the water level in north eastern part, and south western parts of the country. Most of the wells have been showing fall of water level in the range of 0-2 m and are common in all the eastern states. Fall in water level more than 2meters has also been observed in various parts of the states such as Delhi, Madhya Pradesh, Bihar, Jharkhand, Punjab, Haryana and Gujarat state. Rise in water level in the range of 0-2 m and 2-4 m is observed any Central Maharashtra, Andhra Pradesh, southern Rajasthan and Gujarat states. About 58.92% wells are showing rise in water level. Out of which 41.43% wells are shoring rise in water level less than 2 m. About 9.86% wells are showing rise in water level in 2-4 m range and 7.63% wells showing rise in water level more than 4 m. About 41.08 % wells are showing decline in water level, out of which 33.73% wells are showing decline in water level in less than 2 m range.About 5.1% wells are showing decline in water level in 2-4 m range. Only 2.25% wells are showing decline in water level more than 4 m range.

Figure 11
Source: Ground Water Year Book – India 2010-11 by CGWB

SEASONAL WATER LEVEL FLUCTUATIONS

Seasonal Water Level Fluctuation (May 2010 – August 2010)

A comparison of depth to water level during August 2010 with May 2010 (Figure 12) reveals that in general, there is rise in the water level throughout the country except in Tamil Nadu, Western Rajasthan, Punjab and Haryana states. Most of the wells have been showing rise water level in the range of >4 m and are common in all the states except in Tamil Nadu,Western Rajasthan, Punjab and Haryana states. Rise in water level more than 2 meters has also been observed in various parts of the states such as Andhra Pradesh, Madhya Pradesh, Uttar Pradesh, Gujarat, Eastern Rajasthan, Haryana, Punjab and Eastern Maharashtra. About 87% of wells are showing rise in water level. Out of which 39.47%well are showing rise in water less than 2 m. 24.91% wells are shoeing rise in water level in the range of 2-4 m and22.49% wells are showing rise in water level more than 4 m. About 12.95% of well are showing decline in water level.Out of which 10.95% well are showing decline in water less than 2 m.

Figure 12
Source: Ground Water Year Book – India 2010-11 by CGWB

Seasonal Water Level Fluctuation (May 2010 – November 2010)

A comparison of depth to water level data of November 2010 with May 2010 (Figure 13) reveals that, in general there is a rise in water level in almost all states of India except in Rajasthan, Punjab Haryana and Tamil Nadu States. Isolated pockets of fall in water level in the range of 0-2 m have been observed in Rajasthan, Punjab, Haryana and Tamil Nadu. Fall in water level more than 2 m also has been observed Rajasthan and Tamil Nadu states. Out of the total observation wells only 9.6% wells are showing fall in water. Out of this 8% wells are showing fall in water level in less than 2 m range and remaining 1.6% wells are showing fall in water level in the more than 2 m range. Most of the north and north east states showing rise in water level in the range of 0-2 m. Eastern Uttar Pradesh, Bihar and Jharkhand states are showing rise in water level in the range of 2-4 m. Gujarat, Maharashtra, Andhra Pradesh, Orissa, Karnataka and North Tamil Nadu State are showing rise in water level more than 4 m. Out of total monitored wells, 94.4% wells are showing rise in water level. Out of this 46.57% wells are showing rise in water level in 0-2 m range. 24.41% wells are showing rise in 2-4 m range in water level. Remaining 19.4% of monitoring wells are showing rise in water level more than 4 m.

Figure 13
Source: Ground Water Year Book – India 2010-11 by CGWB

Seasonal Water Level Fluctuation (May 2010 – January 2011)

A comparison of depth to water level data of January 2011 with May 2010 (Figure 14) reveals that, in general there is a rise in water level in almost all the states of India except in Rajasthan, Punjab and Haryana States. Isolated pockets of fall in water level in the range of 0-2 m have been observed in Rajasthan, Punjab, Haryana and Madhya Pradesh states. Fall in water level more than 2 m also has been observed Rajasthan, Punjab, Haryana, Madhya Pradesh and Tripura states.Out of the total observation wells only 13.16% wells are showing fall in water. Out of this 10.7% wells are showing fall in water level in less than 2 m range and remaining 2.46% wells are showing fall in water level in the more than 2 m.Most of the north and north east states showing rise in water level in the range of 0-2 m. Eastern Uttar Pradesh, Bihar and Jharkhand states are showing rise in water level in the range of 0-2 m. Gujarat, Maharashtra, Andhra Pradesh, Orissa, Karnataka and North Tamil Nadu State are showing rise in water level more than 4 m. Out of total monitored wells, 86.83% wells are showing rise in water level. Out of this 44.72% wells are showing rise in water level in 0-2 m range. 22.99% wells are showing rise in 2-4 m range in water level. Remaining 19.12% of monitoring wells are showing rise in water level more than 4 m range.

Figure 14
Source: Ground Water Year Book – India 2010-11 by CGWB

RAINFALL VARIATIONS

In India, rainfall is unevenly distributed spatially and temporally. The average annual rainfall of the country for 2010 is almost equal to the Normal rainfall of India. From the perusal of Average Annual Rainfall 2010 map given as Figure 15, it can be observed that the rainfall is excess in southern states except in Kerala, parts of western Tamil Nadu and southern Karnataka. In the northern and northwestern part of the country rainfall is in excess. The Madhya Pradesh, south-eastern Rajas, Madhya Pradesh, Chhattisgarh, Orissa, western Uttar Pradesh, western Gujarat, Punjab,Himachal Pradesh north-east states except Assam and Meghalaya has receive normal rainfall. Rainfall is deficient in eastern Uttar Pradesh, Bihar, Jharkhand south and central west Bengal, Assam and Meghalaya States. A review of annual ground water availability, contribution from monsoon rainfall recharge and annual ground water draft indifferent states falling under over exploited category and the rainfall distribution in space brings a paradoxical situation in the sense that, withdrawal of ground water is not solely responsible for declining trends, the scantly and low rainfall resulting in meager monsoon recharge is equally important. Majority of the ground water stress are as categorized as over exploited and critical units also lies in these states.

Figure 15
Source: Ground Water Year Book – India 2010-11 by CGWB

CATEGORIZATION OF ASSESSMENT UNITS

Out of 5723 assessed administrative units (Blocks/ Talukas/ Mandals/ Districts), 4078 units are 'Safe', 550 units are 'Semi-critical', 226 units are 'Critical', 839 units are 'Over-exploited' and 30 units are 'Saline'. Number of Over-Exploited and Critical administrative units are significantly higher (more than 15% of the total assessed units) in Andhra Pradesh (where categorization was done up to sub-unit level i.e. within Mandal – command and non command-wise), Delhi, Gujarat, Haryana, Karnataka, Punjab, Rajasthan and Tamil Nadu and also the UTs of Daman & Diu and Pondicherry (Figure 16).

Figure 16
Source: Ground Water Year Book – India 2010-11 by CGWB

REFERENCES

  1. Central Ground Water Board Website
  2. CGWB (December 2011) Ground Water Year Book – India 2010-11Download
  3. CGWB Annual Report of 2008-2009


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