International Journal of Engineering Trends and Technology (IJETT) – Volume 3 Issue 3 No 3 – May 2012
An Assessment of Groundwater Quality and its parameters
around Perungudi, the southern part of Chennai, India.
A. Ambica* , Saritha Banuraman, K. Ilayaraja
Department of Civil Engineering, Bharath University, Chennai
Abstract
Groundwater quality has a special significance for domestic, industrial and drinking water supply. In this
paper we here summarized the laboratory results of all the samples collected from the study area and the
spatial distribution of their hydro geochemical parameters were shown as maps. Water Quality Index (WQI)
was then calculated to find the aptness of water for drinking purpose. The overall view of the water quality
index of the present study area reveals that most of the study area are around <75 standard rating of water
quality.
Keywords: Groundwater quality, Spatial distribution, Inverse Distance Weighting (IDW), Geographical Information
System (GIS).
1. Introduction:
As the growth rate of urbanization and industrialization in the metropolitan cities such as Chennai are too
fast, there is an increasing demand on water and equivalent increase on pollution of the groundwater and the
degradation of the existing wetlands is noted overall. The pollution (Shanmugam et al. 2005) gets increasing day by
day due to the ever increase of population. Thus the quality of the water must be expressed in mathematical or any
other physical form in order to explore the character of the water. The water quality index (WQI) is an efficient
method (Mishra et al. 2001, Naik et al. 2001, Singh 1992, Tiwari et al. 1985) in defining the characteristics of the
water (Brown et al. 1972). In groundwater study, WQI helps in categorizing the water whether it is fit or unfit for
drinking. The calculation of the water quality index originally started with Horton (1965) and Landwehr (1974).
Indexing a perfect definition for the water quality was further developed by several researchers there onward. Brown
and his colleagues (1972) developed a water quality index by assigning proper weightage for the parameters based
on their analysis. The contaminants which alter the groundwater both physically and chemically can be altogether
expressed in WQI. This index is the reduction of large amount of water quality data into a single numerical value
(Ratnakanth Babu et al. 2011, Ramakrishniah et al. 2009).
In order to estimate the groundwater quality index, several parameters has to be analyzed and proper
weightage must be assigned for each one. The most important parameters of the groundwater are pH, electrical
conductivity, turbidity, total hardness, total dissolved solids, dissolved oxygen, total alkalinity, sodium, chlorides
and iron. pH is the measure of hydrogen ion activity in the water or other solutions. Pure water has pH value close to
7 at 25°C. Solutions with pH less than 7 are termed as acidic and solutions with pH greater than 7 are termed as
basic or alkaline. Exposure to extreme pH values (both low and high pH) results in irritation to the eyes, skin and
mucous membrane for humans (WHO Guidelines for drinking water quality). Electrical conductivity is generally
used as an indicator of the amount of salt and ion contents present in the water. The purer the water, lower the
conductivity and higher the resistivity. Groundwater conductivity is measured in micro-mhos/cm.
Turbidity is the haziness of the water caused by the suspended individual particles. Groundwater can
contain suspended solid mater of varying sizes. The heavier particles can quickly settle at the bottom whereas the
suspended solids are not enough heavy to get settled up remain in suspension and lead to appear as turbid. The unit
of turbidity is NTU (Nephelometric Turbidity Unit). The hardness of the water depends on the amount of minerals
present in it. Hardness is caused by the compounds of calcium and magnesium and also by several other minerals.
Water is an excellent solvent and readily dissolves the minerals which come in contact with it. As the groundwater
moves through the soil and rocks, it dissolves very small amounts of minerals and holds them in solution. The
dissolved calcium and magnesium in water are the two most common minerals that make the water ‘hard’.
Generally total hardness is measured in mg/l. Total dissolved solids are the inorganic substances that are present in
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International Journal of Engineering Trends and Technology (IJETT) – Volume 3 Issue 3 No 3 – May 2012
the dissolved form. The sizes of these dissolved substances are even less than two micrometer and cannot be
detected in the sieve tests. TDS is measured in parts per million (ppm).
Dissolved oxygen is a measure of the amount of gaseous oxygen (O2) dissolved in the water. Oxygen gets
into water by diffusion from the surrounding air, by aeration. Open wells contain high dissolved oxygen as they are
exposed to open air whereas the bore wells have comparatively less exposed has low level of dissolved oxygen.
Alkalinity can neutralize the acid nature of the water. It is the sum of addition of all the bases present in the water.
Bicarbonate is the dominant anion which contributes much larger part to alkalinity.
Sodium compounds are commonly found in the rocks and soil about a significant percentage. The
groundwater gets sodium as they flow through it by dissolving. The rise in sodium in the groundwater acts one of
the key components for the finding of saltwater intrusion in the coastal areas. It is measured in mg/l. Chlorine is
never found in free form in nature and most commonly occurs as sodium chloride. As like sodium, the chlorine
compounds are highly soluble in water and thus the groundwater gets chlorides by dissolving it. It is measured in
mg/l. Iron is also an important composition of groundwater which is essential for drinking in small amounts. It is a
naturally occurring metal present in many types of rock. Concentrations of iron in groundwater are often higher than
those of measured in surface waters proves that the metal got in groundwater by dissolution. The drinking water
limit of iron must be less than 0.3mg/l.
No such studies on ground water in and around Perungudi have been carried out and this led to carry out
our research. The objective of the current study is to discuss drinking water quality based on the water quality index.
2. Study Area
Perungudi is situated about 20 kilometers from the heart of the Chennai city and 4 kilometers away from
the coast (Figure 1). It is surrounded by the old Mahabalipuram Road and the Perungudi lake. The neighbouring
areas include Kandhan Chavadi to the north, Thoraipakkam to the south and Palavakkam the east side. The natural
landscapes such as Perungudi lake and Pallikaranai marsh land are situated on the western part. The study area is
elevated 9m from the mean sea level and the population in and around is highly increasing each year. It is roughly
said that there was population around 2000 before two decades, and now it is estimated around more the 50000
residents live in it.
3. Data and Methods:
3.1 Insitu data
The water samples were collected from fifteen different open and tube wells in the summer of 2012. During
sampling care was taken as told in the standard procedures of measurement (APHA 1994). Ten parameters such as
pH, electrical conductivity, turbidity, total hardness, total dissolved solids, dissolved oxygen, total alkalinity,
sodium, chlorides and iron were analyzed to find the water quality index.
3.2 Determination of Water Quality Index:
Water Quality Index (WQI) is a most efficient method for assessing the quality of water. Water Quality
Index (WQI) is a tool for communicating the information on overall quality of water and rates the quality of each
sample locations. It acts as the perfect indicator of the quality of the water. It was first proposed by Horton (1965) to
determine the suitability of the groundwater for drinking purposes. Analyzed groundwater sample data are tabulated
in Table1. WQI is computed adopting the following formula.
n
WQI 
 Wi qi
i 1
n
 Wi
i 1
Where, W is the unit weightage factor computed using the following equation, Wn  K / S n and K is the
proportionality constant derived from,
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International Journal of Engineering Trends and Technology (IJETT) – Volume 3 Issue 3 No 3 – May 2012


1
K
n1
  
 n 1 S i




 
 
where S n and S i are the Bureau of Indian Standard values of the water quality parameter (Table 2). Quality rating is
calculated using the formula,
 V
 Videal  
q ni   actual
 x100


V

V
s
tan
dard
ideal


Where, q ni is the quality rating of ith parameter for a total of n number of water quality parameters. Vactual is the
value of the water quality parameter obtained from laboratory analysis. Videal is the value of the water quality
parameter can be obtained from the standard tables. Videal for pH is 7,and Dissolved Oxygen is 14.6 mg/lit and for
other parameters it is equivalent to zero. Vs tan dard is the BIS standard of the water quality parameter. Based on the
WQI values, the water quality is rated as excellent, good, poor, very poor, and unfit for human consumption (Table
3).
3.3 Spatial distribution of the water quality parameters
Spatial distribution is a graphical display that summarizes the data in two or more axes that is used to draw
many conclusions. Spatial distribution of water quality parameters is a model representation of the water quality
parameters distributed in the study area. The spatial distribution is done here by the Geographical Information
system (GIS) software ArcGIS 9.3. The GIS is the sophisticated tool to describe the spatial analysis of the
distribution of the water quality on the two or more axes. Inverse Distance Weighting (IDW) is used in the spatial
analysis of the groundwater. IDW is a type of deterministic method for multivariate interpolation with a known
scattered set of points. The assigned values to unknown points are calculated with a weighted average of the values
available at the known points.
4. Results
The study area has pH as low as 6.6 and high upto 8.8. Stations 1 & 2 are spotted with high pH and station
15 has low pH (Figure 2). Station 3 to station 11 has more alkaline pH greater than 8 mainly at the verge of fit for
drinking. Stations 12, 13 and 14 fall under the range of normal pH. It is also noted that pH alone cannot be the
ultimate factor which is fit for drinking but also many other parameters contributes to it to state whether the water is
fit or not. Stations 11 to 15 are under low conductivity range and stations 1 to 6 has high conductivity even
exceeding more than 2500 micro-mhos/cm. Stations 7 to 10 having moderate conductivity varying between 1500 to
2150 micro-mhos/cm. The east zone of the study area is comparatively good when compared with the west zone
(Figure 3).
Turbidity varies from as low as 0.1 to the maximum of 12.3 NTU. The stations 13 to 14 have very low
turbidity and stations 1 to 6 have high turbidity. Stations 7 to 12 are spotted with moderate turbidity varying within 3
to 9.7 NTU (Figure 4). Station 1 has the highest amount of hardness as 750 and the station 15 has the lowest of 150
mg/l. Stations 2 to 14 are in moderate range of 630, 610, 600, 600, 550, 470, 400, 385, 385, 330, 160, 215 and 160
mg/l respectively (Figure 5). TDS varying within the range of 100 to 750 mg/l. Stations 13 to 15 are within the range
of 100 and 150 mg/l. Station 1 has the high TDS content of 750mg/l and stations 2 to 12 are decreasing as 600, 550,
450, 400, 350, 350, 300, 300, 250, 200 and 200 mg/l respectively (Figure 6). Stations 1 to 5 have very low dissolved
oxygen ranging 10.5, 11.5, 12.5, 14 and 15 whereas stations 11 to 15 have high as 51, 56, 57.5, 62 and 77.5 mg/l.
Stations 6 to 10 have 17.5, 18, 20, 27.5 and 27.5 mg/l respectively (Figure 7).
Alkalinity of the study area varies from 50 to 390 mg/l whereas the stations 1 to 5 are found to have high
alkaline nature and stations 13 to 15 have very low alkaline. Rest of the stations is moderate and ranges between 300
to 350 mg/l (Figure 8). Sodium in the study area is found to be higher than the permissible limit (>100 mg/l).
Stations 13 to 15 have normal sodium range and the other stations vary from 200 to 370 mg/l (Figure 9). Similarly
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chlorides also have high values and are greater than the permissible limit (250 mg/l). Stations 12 to 15 are normal
and the other stations vary from 800 to 1029.5 mg/l (Figure 10). Thus the level of the high sodium and chlorides
portrays that the sea water has been intruded in this region. Iron content in this region is very low and all the stations
come under the bar limit of 0.3 mg/l (Figure 11).
The water quality index of the study area varies from 25 to 45. This range falls under the category of good
(Table 3). The station 15 has the highest WQI and very close to the poorer range (Figure 12). The study area
groundwater is capable for the human consumption.
Conclusion
The spatial distribution of the groundwater parameters and WQI are studied here. The spatial distribution of the
water quality parameters are obtained by the Inverse Distance Weighting method. Overall contribution of the
parameters says that the groundwater quality is not bad throughout the study area. But the conductivity, dissolved
solids, sodium and chlorides are considerably high and further increase in any parameter may lead to severe water
quality problems. It is seen from the calculation that none of the stations fall under the excellent range and none of
them fall beyond poor range of water quality index. However, at present the study area is consistent but can go
beyond to the poor range due to urbanization around the Perungudi. So that study indicates the water in that area
needs some purification process for drinking purpose.
References
1. APHA (American Public Health Association). (1994). Standard method for examination of water and wastewater,
NW, DC 20036.
2. BIS: Standards for water for drinking and other purposes. Bureau of Indian standards publication, New Delhi
(1983).
3. Brown, R. M., McLelland, N. I., Deininger, R. A. & O'Connor, M. F. (1972). A water quality index - crashing the
psychological barrier. Indicators of Environmental quality.
4. Horton R.K. (1965). An index number system for rating water quality. J. Water Poll.Cont. fed., 37, pp 300.
5. Landwehr, J. M., (1974), Water Quality Indices Construction and Analysis, Ph.D. Thesis, University of Michigan,
Ann Arbor, Michigan, USA.
6. Mishra, P.C., & Patel, R.K. (2001). Study of the pollution load in the drinking water of Rairangpur, a small tribal
dominated town of North Orissa. Indian J. Environ. Ecoplanning, 5(2): 293-298.
7. Naik, S. & Purohit, K.M. (2001). Studies on water quality of river Brahmani in Sundargarh district, Orissa. Indian
J. Environ. Ecoplanning, 5(2): 397-402.
8. pH in Drinking-water, WHO Guidelines for Drinking-water Quality. WHO/SDE/WHO/03.04/12
9. Ramakrishniah, C.R., Sadashivaiah, C., & Ranganna, G. (2009). Assessment of Water Quality Index for the
Groundwater in Tumkur Taluk. E-Journal of Chemistry. 6(2), 523-530.
10. Ratnakanth Babu, M.J. (2011). Assessment of Groundwater Pollution in Parts of Guntur District Using Remote
Sensing & GIS, International Journal of Earth Sciences and Engineering, Volume 04, No 06 SPL, pp 1024-1030.
11. Shanmugam, P., Neelamani, S, Ahn, Y. H, Philip. L., Hong G. H. (2007). Assessment of the levels of coastal
marine pollution of Chennai city, Southern India. Water Resour Manage 21:1187–1206 DOI 10.1007/s11269-0069075-6
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International Journal of Engineering Trends and Technology (IJETT) – Volume 3 Issue 3 No 3 – May 2012
12. Singh, D.F. (1992). Studies on the water quality index of some major rivers of Pune, Maharashtra. In the
Proceedings of the Academy of Environ. Biol., 1(1): 61-66.
13. Tiwari, T.N. & Mishra, M.A. (1985). A preliminary assignment of water quality index of major Indian rivers.
Indian J. Environ. Protection, (5): 276-279.
14. WHO (World Health Organization). (1993). Guidelines for drinking water quality, 2nd Ed., Vol 1, p 188.
Table 1: Groundwater sample analysis results of Perungudi region
Sample
Stations
pH
Chlorides
Total
Alkalinity
DO
Total
Hardness
Iron
Sodium
TDS
EC
Turbidity
s1
8.8
1029.5
390
10.5
675
0.0402
370
750
3144
12.3
s2
8.6
994
375
11.5
630
0.0402
368
600
3012
12.8
s3
8.6
958
370
12.5
610
0.031
366
550
2882
11.1
s4
8.5
940.75
360
14
600
0.0312
366
450
2616
10.5
s5
8.4
937
350
15
600
0.037
345
400
2501
10
s6
8.3
923
350
17.5
550
0.038
311
350
2330
10.2
s7
8.3
937.7
350
18
470
0.03
325
350
2114
9.7
s8
8.2
905.25
350
20
400
0.0336
301
300
1971
9.4
s9
8.2
900
300
27.5
385
0.034
228
300
1667
9.4
s10
8.2
905.25
345
27.5
385
0.034
227
250
1610
7.4
s11
8.2
887.5
325
51
330
0.022
260
200
1237
3.4
s12
7.1
881.3
300
56
160
0.021
200
200
1100
3
s13
7.1
159.75
75
57.5
215
0.021
180
150
997
1.3
s14
7.1
147.32
60
62
160
0.02
155
150
981
1.3
s15
6.6
124.25
50
77.5
150
0.02
140
100
860
pH -No Unit, Electrical Conductivity – micro-mhos/cm,Turbidity-NTU For all other parameters are assigned mg/lit
Table 2: Unit weightage based on the Bureau of Indian drinking water standard (IS: 10500, 1993)
Parameters
pH
Chlorides
Total Alkanity
Dissolved Oxygen
Total Hardness
Iron
Sodium
TDS
Electrical Conductivity
Turbidity
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Standard Values (Si)
6.5-8.5
250
200
4
300
0.3
100
500
300
5
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Unit Weight (Wi )
0.029948
0.0010182
0.0012728
0.06364
0.0008485
0.84854
0.0025456
0.00050912
0.0008485
0.0509124
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International Journal of Engineering Trends and Technology (IJETT) – Volume 3 Issue 3 No 3 – May 2012
Table 3: Water quality index categories
WATER QUALITY INDEX
DESCRIPTION
0-25
Excellent
26-50
Good
51-75
Poor
76-100
Very Poor
>100
Unfit For Drinking
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International Journal of Engineering Trends and Technology (IJETT) – Volume 3 Issue 3 No 3 – May 2012
Figure 1: Study area Map
Figure 2: Spatial
distribution of pH
Figure 3: Spatial
Conductivity (micro-
distribution of Electrical
mhos/cm)
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Figure 4: Spatial
distribution of Turbidity (NTU)
Figure 5: Spatial
(mg/l)
distribution of Total Hardness
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Figure 6: Spatial distribution of Total Dissolved Solids (mg/l)
Figure 7: Spatial
Oxygen (mg/l)
distribution of Dissolved
Figure 8: Spatial
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distribution of Total Alkalinity
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International Journal of Engineering Trends and Technology (IJETT) – Volume 3 Issue 3 No 3 – May 2012
Figure 9: Spatial distribution of Sodium (mg/l)
Figure 10: Spatial
(mg/l)
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distribution of chlorides
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International Journal of Engineering Trends and Technology (IJETT) – Volume 3 Issue 3 No 3 – May 2012
Figure 11: Spatial distribution of Iron (mg/l)
Figure 12: Spatial
Quality Index
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