statistical study on pre & post monsoon variation of ... · in theni district, tamil nadu ......

INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 1, No 5, 2011

© Copyright 2010 All rights reserved Integrated Publishing Association

Research article ISSN 0976 – 4402

Received on December, 2010 Published on January, 2011 798

Statistical Study on Pre & Post Monsoon Variation of Groundwater Level in Theni District, Tamil Nadu – India

Sukumar.S 1 , Sankar.K 2 1 Research Scholar, Department of Industries & Earth Sciences, Tamil University,

Thanjavur 613005, TN, India 2 Associate Professor, Department of Industries & Earth Sciences, Tamil University,

Thanjavur 613005, TN, India. [email protected]

ABSTRACT

The water table is the level at which the groundwater pressure is equal to atmospheric pressure. It may be conveniently visualized as the 'surface' of the groundwater in given vicinity. It usually coincides approximately with the 'phreatic surface', but can be many feet above it. As water infiltrates through pore spaces in the soil, it first passes through the zone of aeration, where the soil is unsaturated. At increasing depths water fills in more spaces, until the zone of saturation is reached. The ability of the aquifer to store groundwater is dependent on the primary and secondary porosity and permeability of the rock or soil. The form of a water table may change and vary due to seasonal changes, topography and structural geology. In some regions, winter precipitation is often higher than summer precipitation and so the groundwater storage is not fully recharged in summer.

Keywords: Insufficient rainfall, groundwater fluctuation & groundwater depth variation.

1. Introduction

The groundwater level fluctuation is controlled by recharge and draft of groundwater and the diverse influences on groundwater levels include meteorology, tidal phenomena, urbanization, earthquakes and external loads Stress and strain in water level due to groundwater recharge, discharge and intensity of rainfall are reflected in groundwater level fluctuation with time (Gopinath & Seralathan., 2008). The mean annual rainfall over India is about 105 cm and exceeds the global average rainfall of 70 cm. Even then, about 80% of the Indian territories fall under semiarid conditions. This is because of spatial and tempral distribution of rainfall, overall variabilities of monsoon, topographic variations, prevailing semiarid to arid climatic conditions and varied nature of hydrogeology (S.N. Rai). Moreover, overexploitation, excessive agriculture, untreated effluents and wastes have caused deterioration in groundwater quality. Whereas paucity of clean drinking water can affect the general health and life expectancy of people (Nash & McCall 1995), the use of poor quality water in irrigation can degrade the soils due to contamination (Palaniswami & Ramulu 1994; Datta et al., 2000; Patel et al., 2004; Marechal et al., 2006). The lowering of groundwater levels has resulted in reduction in individual well yield, growth in well population, failure of bore wells, drying up of dug wells and increase in power consumption (Imtiyaz & Rao 2008). Groundwater is often developed without proper understanding of its occurrence in time and space and is, therefore, threatened by overexploitation and contamination. For that reason, groundwater management is the key to combat the emerging problem of water security. Knowledge of water table depth is a crucial element in many hydrological investigations,

http://en.wikipedia.org/wiki/Precipitation_(meteorology)


S. Sukumar, K. Sankar International Journal of Environmental Sciences Volume 1 No.5, 2011

799

including agricultural salinity management, landfill characterization, chemical seepage movement, and water supply studies (Buchanan &Triantafilis 2009).

1.1 Material and Methodology

Theni district is bordered by the Kerala State on the west, Madurai district in the east. Dindigul district in the north and Kerala and Virudhunagar district in the south. The district is part of composite cape comerin to Cauvery basin and a part of vaigai sub basin. Vaigai river has its origin in the eastern slope of Western Ghat at Gandamanayakanur. Suruliar, Theniar, Varahanadhi and Manjalar are its main tributaries. The preparation of Statistical Study on Pre & Post Monsoon Variation of Groundwater level is done by collection and analysis of various information from the study area such as Location Map ( Prepared from Survey of India, 50;000 scale toposheets) drainage Map (prepared from Using ASTER DEM imgery, Metrological & Rainfall data ( collected from Indian Meteorological Dept ) , Pre and Post monsoon Depth to Water Level and Water Level Fluctuation Map ( Collected from Central Groundwater Board Chennai) etc., using Arc Map 9.3 and ENVI 4.6 software for Remote sensing and GIS technology.

1.2 Description of the Study Area

The study area covers 2889 sq. km falling in parts of Tamil Nadu State (India), Theni districts. It occurs between North Latitudes 09º 30' and 10º 00 and east longitude 77º 10' and 77º 30'. It comprises five taluks, namely, Bodinayakkanur, Periyakulam, Theni, Andipatti and Uthamapalayam with Theni as its district headquarters and occupies an area about 2700 sq.km (Fig.1). The region is entirely covered by alluvial deposits of quaternary to recent age consisting of clay and sand. Kankar, gravel, cemented and unconsolidated sand are also found in the beds. The elevation varies from 1 to 80 degree from mean sea level; the district may be divided in hilly terrain units.

1.3 Temperature

The mean daily temperature is highest during the month of May and it is lowest in the month of January. The mean daily maximum and minimum temperature observed at Madurai IMD station are 37.5ºC during the month of May and 20.9ºC during January.

1.4 Relative Humidity

In general, the humidity is high and is highest during the month of November. The relative humidity in the catchment ranges from 37 to 75 percent.

1.5 Wind Speed

Winds are generally light to moderate with some strengthening in monsoon season. The catchment is influenced by winds from south – west and north – west during June to September and from north – east and southeast during October to April. The average wind speed in the catchment varies from 4.9 to 9.6 km/hr.



800

Figure 1: Location map of Study Area

1.6 Cloud Cover

Sky is generally heavily clouded during the monsoon months. In t he post – monsoon, cloudiness decreases. During the rest of the year, the sky is clear or lightly clouded. The cloud cover in the catchment ranges from 3.7 to 6.8 okras.



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1.7 Rainfall and Climate

The district receives rainfall under the influence of both southwest and northeast monsoon. The rainfall data from 3 stations viz. Periyakulam, Bodinayakanur and Uthamapalayam for the period 99 years (19011999) have been considered for the analysis (Table.1). Normal annual rainfall is of the order of 791.2 mm out of which 47% (375.5) received during NE Monsoon and 22% (172.7) is received during SW monsoon. The mean daily minimum temperature varies from 20.9°C (January) to 26.3°C (May) and mean daily maximum temperature varies from 29.7°C (December) to 37.5°C (May).

Figure 2: Drainage Map

2. Basin and subbasin

The district is part of composite cape comerin to cauvery basin and a part of vaigai sub basin.

2.1 Drainage

Vaigai river has its origin in the eastern slope of Western Ghat at Gandamanayakanur. Suruliar, Theniar, Varahanadhi and Manjalar are its main tributaries. The regional drainage pattern is dentritic and major direction of the flow of river is easterly (east, southeast and northeast) from this Western Ghat hills (fig.2).



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2.2 Geomorphology

The study area is characterised predominantly by structural and denudational land forms viz., structural hills, residual hills, linear ridges and pediment. Bazada zone is found well developed at the foot hills on the western and northern part of the district. The valleys are characterised by colluviofluvial sediments. The hilly terrain act as catchment area and runoff zones while the bazada zone bordering the hills form a good recharge zones.

2.3 Soils

The study area is characterised by Red, Black and Brown soils. The major part of the area is characterised by red soil, which can be either transported. These are medium to heavy textured soils with moderate to higher permeability. The black soils are limited to less than 1% of the area. They are fine textured with low permeability. The brown soils are limited to less than 1% of the area and they characterised by low permeability.

2.4 Regional Geology

The study area having following lithology, Calc Granulite and lime stone, Calcareous gritty sandstone and clay, Charnockite, Garnet biotite gneiss, Granite and Hornblende biotite gneiss.

Table 1: Theni District Rainfall (mm) for Last Five Years

2005 2006 2007 2008 2009

JAN

R/F 0.0

%DEP 100

JAN

R/F 12.5

%DEP 30

JAN

R/F 0.0

%DEP 100

JAN

R/F 0.0

%DEP 100

JAN

R/F 3.7

%DEP 79

FEB

R/F 40.05

%DEP 33

FEB

R/F 0.0

%DEP 100

FEB

R/F 0.0

%DEP 100

FEB

R/F 36.3

%DEP 19

FEB

R/F 0.0

%DEP 100

MARCH

R/F 73.1

%DEP 23

MARCH

R/F 58.7

%DEP 1

MARCH

R/F 0.0

%DEP 100

MARCH

R/F 256.2

%DEP 333

MARCH

R/F 41.7

%DEP 30

APRIL

R/F 146.7

%DEP 48

APRIL

R/F 55.7

%DEP 44

APRIL

R/F 49.3

%DEP 50

APRIL

R/F 38.5

%DEP 61

APRIL

R/F 54.3

%DEP 45

MAY MAY MAY MAY MAY



803

R/F 76.8

%DEP 19

R/F 79.9

%DEP 24

R/F 10.8

%DEP 83

R/F 29.8

%DEP 54

R/F 61.2

%DEP 5

JUNE

R/F 34.9

%DEP 91

JUNE

R/F 26.8

%DEP 46

JUNE

R/F 81.4

%DEP 345

JUNE

R/F 60.5

%DEP 231

JUNE

R/F 42.3

%DEP 131

JULY

R/F 50.4

%DEP 86

JULY

R/F 3.0

%DEP 89

JULY

R/F 50.8

%DEP 87

JULY

R/F 70.9

%DEP 162

JULY

R/F 103.7

%DEP 283

AUGUST

R/F 27.9

%DEP 23

AUGUST

R/F 25.4

%DEP 30

AUGUST

R/F 53.4

%DEP 48

AUGUST

R/F 140.3

%DEP 288

AUGUST

R/F 42.7

%DEP 18

SEPTEMBER

R/F 34.6

%DEP 64

SEPT

R/F 62.1

%DEP 36

SEPT

R/F 51.7

%DEP 47

SEPT

R/F 73.3

%DEP 24

SEPT

R/F 81.9

%DEP 15

OCTOBER

R/F 275.5

%DEP 47

OCTOBER

R/F 221.8

%DEP 19

OCTOBER

R/F 263.2

%DEP 41

OCTOBER

R/F 257.1

%DEP 38

OCTOBER

R/F 80.0

%DEP 57

NOVEMBER

R/F 204.0

%DEP 47

NOVEMBER

R/F 194.6

%DEP 40

NOVEMBER

R/F 108.6

%DEP 22

NOVEMBER

R/F 59.8

%DEP 57

NOVEMBER

R/F 274.7

%DEP 97

DECEMBER

R/F 158.1

%DEP 173

DECEMBER

R/F 0.0

%DEP 100

DECEMBER

R/F 204.9

%DEP 253

DECEMBER

R/F 20.3

%DEP 65

DECEMBER

R/F 27.8

%DEP 52

(Source: India Meteorological Dept, Hydromet Division)

Note: R/F Arithmetic averages of Rainfall of Stations under the District.

%DEP Departures of rainfall from the long period averages of rainfall.



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2.5 Water Level Fluctuation

A perched water table (or perched aquifer) is an aquifer that occurs above the regional water table, in the vadose zone. This occur when there is an impermeable layer of rock or sediment (aquiclude) or relatively impermeable layer (aquitard) above the main water table/aquifer but below the surface of the land. If a perched aquifer's flow intersects the Earth's dry surface, at a valley wall for example, the water is discharged as a spring. Seasonal fluctuations occur in the water table and during the dry season, river beds may dry up.

The fluctuation in groundwater level is monitored every month. The groundwater level reached the lowest level in the district or hottest periods after which it starts rising to reach highest peak, a little the end of rainy seasons. The rise and fall depends upon the amount, duration and intensity of precipitation, depth of weathering, specific yield of the formation etc. A general overall view of the water level fluctuation suggests that the water level trends to rise during the year 2004 to reach the peak an starts receding from May onwards to the end of Jan 2005 Figure (3 to 5).

Figure 3:Water Level Fluctuation Map (Decadal Mean 1995 – 2004 & Jan 2005)

http://en.wikipedia.org/wiki/Vadose_zone

http://en.wikipedia.org/wiki/Aquiclude

http://en.wikipedia.org/wiki/Aquitard

http://en.wikipedia.org/wiki/Spring_(hydrosphere)



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Figure 4:Water Level Fluctuation Map (Decadal Mean Jan 2004 – Jan 2005)



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Figure 5: Water Level Fluctuation Map (Decadal Mean May 2004 – Jan 2005)

2.6 Depth to Water Table

Water precipitated as rain reaches ocean in two ways: on the surface as streams and beneath the surface through rocks. Water escaping seepage runs as surface flow and is channelised toward the sea. Water entering into the ground accumulates and slowly finds its way towards oceans. Water, in its hydrologic cycle enters and leaves the ground receiving the name groundwater. Groundwater is available up to 750m from the surface of the earth below which it decreases in amount. The reason is that the rocks are well compacted by pressure due to overburden. The water table may be met within a few meters in humid regions and below a hundreds of meters in desert regions. Water table is at the surface in swamps and lakes. The level of water table and its fluctuation is measured from the wells, springs and rivers (Radhakrishnan 1978).The water table parallels the topography of the region. That is under hills it is mound shaped; under valleys it is valley shaped. This is due to the slow lateral movement of groundwater.



807

At hill top infiltration is greater. But along flanks surface runoff is greater. However, the water table flattens during drought period. Within the zone of aeration sometimes impermeable rocks occur. It prevents downward movement of this layer. And the water table is known as perched water table.

The depth to water table is closely related to the topography, subsurface lithology, precipitation, and also to the irrigation channels and surface water bodies. The measurement of depth to water table during the year gives an indication of mutual relationships between the discharge and the total recharge from different sources. The changes observed are useful for recording the longterm fluctuation in the water levels and assist in computing the water balance of the area. The depths to water table were observed in both premonsoon and post monsoon periods in the study area (Fig.6, 7 & 8). The minimum depth of water table in the range of 2 to 20 m was mostly recorded in Theni district.

Figure 6: Depth to Water Level – Premonsoon May 2005



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Figure 7: Depth to Water Level – Premonsoon May 2006



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Figure 8: Depth to Water Level – Postmonsoon Jan 2007



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Table.2 (2005 to 2007) Depth to Water Level Status of Theni District

B1 – Andipatti, B2 – Bodinayakanur, B3 – Chinnamanur, B4 – Kambam,

B5 – Myladumparai, B6 – Periyakulam, B7 Theni, B8 – Uthmapalayam.

PreM – Premonsoon, PostM – Postmonsoon.

Water Level & Area in sq/km

Block Name / Year Total Area In

(sq/km) 0 – 2

(m.bgl.) (Area in sq/km)

2 – 5 (m.bgl.) (Area in sq/km)

5 – 10 m.bgl.) (Area in sq/km)

10 – 20 (m.bgl.) (Area in sq/km)

B1 – PreM – May 05 255.98 0 35.15 184.88 0 B1 – PreM – May 06 255.98 0 86.23 133.81 0 B1 – PostM – Jan 07 255.98 0 21.84 214.25 0 B2 – PreM – May 05 450.01 60.40 345.00 100.48 0 B2 – PreM – May 06 450.01 30.37 342.93 132.58 0 B2 – PostM – Jan 07 450.01 0 302.21 240.39 0 B3 – PreM – May 05 234.18 0 146.53 75.51 0 B3 – PreM – May 06 234.18 0 52.78 169.27 0 B3 – PostM – Jan 07 234.18 0 212.62 25.54 0 B4 – PreM – May 05 460.55 0 0 79.52 436.00 B4 – PreM – May 06 460.55 0 0 42.06 473.46 B4 – PostM – Jan 07 460.55 0 7.56 103.21 441.93 B5 – PreM – May 05 590.32 0 28.55 278.82 166.06 B5 – PreM – May 06 590.32 0 0 348.31 125.12 B5– PostM – Jan 07 590.32 0 246.21 224.38 31.52 B6– PreM – May 05 376.18 0 46.80 313.94 0 B6– PreM – May 06 376.18 0 260.38 100.35 0 B6– PostM – Jan 07 376.18 0 29.76 357.33 0 B7– PreM – May 05 182.00 0 169.01 0 0 B7– PreM – May 06 182.00 0 134.32 34.69 0 B7– PostM – Jan 07 182.00 0 87.26 94.04 0 B8 – PreM – May 05 278.12 0 91.89 257.89 0 B8 – PreM – May 06 278.12 0 39.25 276.01 34.53 B8 – PostM – Jan 07 278.12 0 139.91 230.72 4.44



811

0

50

100

150

200

250

Area in sq/km

0 – 2 (m.bgl.)

2 – 5 (m.bgl.)

5 – 10 m.bgl.)

10 – 20 (m.bgl.)

Andipatti

May.2005 May.2006 Jan.2007

0

50

100

150

200

250

300

350

Area in sq/km

0 – 2 (m.bgl.)

2 – 5 (m.bgl.)

5 – 10 m.bgl.)

10 – 20 (m.bgl.)

Bodinayakkanur

May.2005 May.2006 Jan.2007

Figure 9: Variation of depth to water Figure 10: Variation of depth to water Level (2005 – 2007 Andipatii Block) Level (2005 – 2007 Bodinayakkanur Block)

Figure 11: Variation of depth to water Figure 12: Variation of depth to water Level (2005 – 2007 Chinnamanur Block) Level (2005 – 2007 Kambam Block)

0

50

100

150

200

250

Area

in

sq/k

m

0 – 2 (m.bgl.)

2 – 5 (m.bgl.)

5 – 10 m.bgl.)

10 – 20 (m.bgl.)

Chinnamanur

May.2005 May.2006 Jan.2007

0 50

100 150 200 250 300 350 400 450 500

Are

a sq

/km

0 – 2 (m.bgl.)

2 – 5 (m.bgl.)

5 – 10 m.bgl.)

10 – 20 (m.bgl.)

Kambam

May.2005 May.2006 Jan.2007



812

Figure 13: Variation of depth to water Figure 14: Variation of depth to Level (2005 – 2007 Myladumparai Block) Level (2005 – 2007 Periyakulam Block

Figure 15: Variation of depth to water Figure 16: Variation of depth to water Level (2005 – 2007 Theni Block) Level (2005 – 07) Uthmapalayam Block

0

50

100

150

200

250

300

350

400

Area

in s

q/km

0 – 2

(m.bgl.) 2 – 5

(m.bgl.) 5 – 10 m.bgl.)

10 – 20 (m.bgl.)

P eyiakulam

May.2005 May.2006 Jan .2007

0

50

100

150

200

250

300

Are

a in

sq/

km

0 – 2 (m.bgl.)

2 – 5 (m.bgl.)

5 – 10 m.bgl.)

10 – 20 (m.bgl.)

Uthamapalayam

May.2005 May.2006 Jan.2007

0

50

100

150

200

250

300

350

Area

in s

q/k

m

0 – 2 (m.bgl.)

2 – 5 (m.bgl.)

5 – 10 m.bgl.)

10 – 20 (m.bgl.)

M yladumparai

M ay.2005 M ay.2006 Jan.2007

0 20 40 60 80

100 120 140 160 180

Are

a in

sq/

km

0 – 2 (m.bgl.) 2 – 5 (m.bgl.) 5 – 10 m.bgl.)

10 – 20 (m.bgl.)

Theni M ay.2005 M ay.2006 Jan.2007



813

3. Conclusions

The district depth to water level is not uniform in the period of 2005 to 2007 (Table.2) and is limited to areas having 2 – 5 (m.bgl) meter blow ground level. Out of 8 blocks, 5 blocks have been categorised as over exploited and 3 blocks as critical (Figure 9 to 16). The type of water level 2 – 5 (m.bgl) predominates in the study area having charnockite rock type. The artificial groundwater recharge; it is essential and their importance in the study area.

4. References 1. Imtiyaz, M. and Rao, D.J.M., (2008), Influence of overexploitation on

groundwater

2. Ecosystem in hard rock terrain. Proceedings of International Groundwater Conference, Jaipur, India.March. 2008. pp 1922.

3. Nash, H. and McCall, G.J.H., (1995), Groundwater quality. In 17th Special Report,Chapman and Hall, London.

4. Buchanan, S. and Triantafilis, J., (2009), Mapping water table depth using geophysical and environmental variables Groundwater, pp.8096.

5. Rai, S.N. Hydrological Studies, National Geophysical Research Institute, Hyderabad , Hydrological Studies, pp 17 27.

6. Gopinath, G and Seralathan, P (2008), Studies on Longterm Variability of Groundwater Level in the Hard Rock Crystalline Terrains of a Central Kerala River Basin, IE (I) JournalAGriver. June.2008. Vol.89, pp 4753.

7. Briz Kishore, B.H and Bhimasankaram, V.L.S (1981), Analysis of Groundwater Hydrographs for Defining a Crystalline Hydrogeological Environment, Journal of Ground Water, SepOct 1981. Vol.19, pp 476481.

8. Goyal, S.K and Chaudhary, B.S (2010), GIS based study of SpatioTemporal changes in Groundwater depth and quality in Kaithal district of Haryana, India, journal of Indian Geophysics Union, April 2010. Vol.14, No.2, pp 7587.

9. Sitarama Prasad Kudarvalli, Ramakoteswara Prasad Kuchipudi and Udaya Bhaskar Pinnamanen. (2010), Hydrological Variations of Groundwater in Different Geomorphic Units of Krishna Eastern Delta, Andhra Pradesh, International Journal of Engineering Science and Technology, 2010, Vol.2 (9), pp 40074012.

10. District groundwater brochure, Central groundwater board, Chennai. Feb 2008.

11. State Environmental Report of Tamilnadu, 2010, 1 st edition.

12. Government of India & Government of The Netherlands Groundwater Year book of Hydrology Project, 2010.

statistical study on pre & post monsoon variation of ... · in theni district, tamil nadu ......

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