International Journal of Scientific & Engineering Re search Volume 3, Issue 7, July-2012 1

ISSN 2229-5518

Assessment of Groundwater Quality Index for

Upper Pincha Basin, Chittoor District, Andhra Pradesh, India using GIS

Hema Latha. T., Pradeep Kumar G.N., Lakshminarayana. P, Anil. A.

ABSTRACT:

Present work is aimed at assessing Water Quality Index (W QI) for groundwater of Upper Pincha Basin, Chittoor District, Andhra Pradesh. This has been carried out by collecting groundwater samples and subjecting them to comprehensive physico-chemical analysis. Results obtained were compared with standard values recommended by W HO for drinking and public health. For computing WQI, eleven parameters viz., pH, TH, Cl, TDS, Ca, Mg, So4, No3, F, HCO3 and Na have been considered. W QI values for the groundwater samples from the study area ranges from 71.99 to 273.82. High value of W QI has been found to be mainly from excess presence of TH, Cl, TDS, Mg and HCO3. Using GIS contouring methods with Arc/View GIS 9.3, spatial distribution maps of pH, TH, Cl, TDS , Ca , Mg , So4

, No3 , F , HCO3 , Na and W QI have been created. W QI is used to assess the suitability of groundwater from the study area for human consumption. From the W QI assessment over 90% of the water samples are found to fall under poor water category. Analysis reveals that

groundwater of the area needs field specific treatment before put to use.

INDEX TERMS: Physico-chemical analysis, Water Quality Index (W QI), Spatial analysis, GIS, Groundwater, Upper Pincha Basin, Inverse Distance Weightage (IDW ).

1. INTRODUCTION

roundwater occurs almost everywhere beneath the earth surface. Knowledge of occurrence, replenishment and recovery of groundwater has special significance in arid and semiarid regions due to spatial and timely variations in monsoon rainfall, insufficient surface waters and over drafting of groundwater resources. Groundwater quality depends on the quality of recharged water, atmospheric precipitation and inland surface water. Temporal changes in the origin and constitution of the recharged water, hydrological and human factors, may cause periodic changes in groundwater quality. Ascertaining the quality is crucial before its use for various purposes such as drinking, agricultural,
recreational and industrial use [1,2,3].
Water Quality Index (WQI) is an important parameter for ascertaining groundwater quality and its suitability for drinking purpose. It is one of the most effective tools to communicate information on the quality of water. It is simple and easy to understand water quality issues by integrating complex data and generating a score that describes water quality status. It is also defined as a
rating that provides the composite influence of water quality parameters on the overall quality of water for human consumption. Standards for drinking purposes as recommended by WHO [4,5] have been considered for the calculation of WQI.
Main objective of the present experimental study is to assess groundwater quality of Upper Pincha Basin by an integrated approach of traditional water quality analysis and Geographical Information System and to generate water quality index map.

1.1 STUDY AREA

Upper Pincha Basin lies between North Latitude
13042’ to 13028’ and East Longitude 78054’ to 780 45’ with a
total drainage 146.26 km2 (Figure 1), and is spread over three mandals; Somala, Sodumu and Chowdapalle. This region is influenced by semi arid climate with temperature varying between 30 0C and 42 0C. Normal annual rainfall over the study area is about 860 mm. Major Industries

Hemalatha T, Assistant professor , Department of Civil Engineering, S.V University College of Engineering, Tirupati.-517502,Andhra Pradesh, India. PH:09640862212 Email: t_hemalata@yahoo.co.in.

Pradeep Kumar G.N, Professor, Department of Civil Engineering, S.V University College of Engineering, Tirupati -517502, Andhra Pradesh, India .Email:

saignp@gmail.com

Lakshminarayana P, Academic Assistant, Centre for Earth, Atmospheric and Weather, JNTUH, Hyderabad, India. Email: narayan_polak@yahoo.co.in

Anil A., Post Graduate student, Department of Civil Engineering, S.V University College of Engineering, Tirupati, India.

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ISSN 2229-5518


located in the study area is sugar, chemicals, food and food processing.
Occurrence, movement and storage of groundwater are influenced by lithology, thickness and structure of the rock formation. Major part of study area covers weathered and fractured rocks of biotite-hornblend gneiss, biotite granite(Hbgn) (Figure 2). Ground water conditions in these types of rocks are mainly controlled by fractured and intergranular porosities. Red loamy soils and black clay soils are found in the study area.

2 MATERIALS AND METHODS

2.1 Chemical Analysis: Water samples, in clean polyethylene bottles, were collected during July 2011 from

50 boreholes capturing the deep aquifer depth ranging
from 300 feet to 600 feet (Figure 3). Before collecting the
samples, bottles were thoroughly rinsed with groundwater
to be sampled. In case of bore wells and hand pumps, water

samples were collected after pumping for 10 min. Eleven characteristics, such as pH, TH, Cl , TDS , Ca , Mg , So4, No3, F , HCO3 and Na, of the groundwater samples were determined using standard procedures recommended by APHA [6]. Parameters including statistical measures, such as minimum, maximum, mean and standard deviation, are presented.
.

Figure 2: Geological map of study area

Figure 3: Groundwater sampling locations

Figure 1: Location map of the study area

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2.2 Estimation of Water Quality Index: For computing WQI, three steps were followed [7]. In the first step, each of the 11 parameters (pH, TDS,TH, Cl, SO4 , HCO3 , NO 3, Ca, Mg, Na and F ) has been assigned a weight () based on their effect on primary health (Table 1).

Table 1: Relative weight of chemical parameters

(2)

is the quality rating, is the concentration of each chemical parameter in each water sample in mg/l and is the WHO standard for each chemical parameter in mg/l
Table 2: Status of Water Quality based on WQI

WQI Range

Status

< 50

Excellent

50-100

Good

100-200

Poor

200-300

Very Poor

>300

Unfit For Drinking

In WQI, the SI is first determined for each chemical parameter using Eq. (3)-which is then used to determine the WQI as per the Eq. (4):

(3)

(4)


Maximum weight of 5 has been assigned to parameters like total dissolved solids, fluorides and nitrate due to their major importance in water quality assessment. Bicarbonate is given the minimum weight of 2 as it plays an insignificant role in the water quality assessment [8]. Other parameters like calcium, magnesium, sodium and sulphate were assigned a weight between 2 and 5 depending on their importance in the overall quality of water for drinking purposes. In the second step, the relative weight ( ) of each parameter is computed using Eq. (1):

(1)

where, is the weight of each parameter, is the number of parameters. Weight (), calculated relative weight () values and the WHO standards for each parameter are given in Table 1. In the third step, quality rating scale (qi) was calculated for each parameter using Eq. (2):
where, is the sub-index of th parameter. Values are usually classified into five categories (Table 2): Excellent, good, poor, very poor and unfit for drinking [9,10].

2.2 WQI Contour Maps through GIS: GIS is a powerful

tool for developing solutions for water resources problems
for assessing water quality, determining water availability,
preventing flooding, understanding the natural
environment, and managing water resources on a local or
regional scale [11]. Visiting every location in a study area to measure the height, magnitude, or concentration of a phenomenon is usually difficult or expensive. Instead, measure the phenomenon at strategically dispersed sample locations, and predicted values can be assigned to all other locations. Input points can be either randomly or regularly spaced or based on a sampling scheme. The interpolation tools are generally divided into deterministic and geostatistical methods. IDW, Spline, and Trend are deterministic, while Kriging is a geostatistical method. The Inverse Distance Weighted (IDW) referred to as deterministic interpolation methods because they assign values to locations based on the surrounding measured values and on specified mathematical formulas that determine the smoothness of the resulting surface. Determines the cell values using a linearly weighted combination of a set of sample points and controls the significance of known points upon the interpolated values.

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The research paper published by IJSER journal is about Assessment of Groundwater Quality Index for Upper Pincha Basin, Chittoor District, Andhra Pradesh, India using GIS 4

ISSN 2229-5518

Groundwater quality classification maps for pH, TH, TDS, Cl, SO 4, HCO3 , NO3 , Ca, Mg, Na and F from thematic
layers, based on the WHO Standards for drinking water, have been created for Upper Pincha Basin.

Table 3: Water Quality Parameters Values for Collected Groundwater Samples at Various Locations

TH

SO²¯

Fluoride

CL¯

TDS

Ca²

Mg²

Na²

NO¯

HCO3

Sample

T(°C)

pH

----------------------------------------------------------------------- mg/l -------------------------------------------

1

33.5

6.57

352

130

0.5

140

800

200

152

32

0.1

210

2

30

8.23

264

130

0.6

180

700

133.33

130.7

34

0.1

180

3

33

7.43

172

60

0.4

80

600

66.6

105.4

35

Nil

320

4

33

7.46

468

150

0.4

250

1200

283.3

184.7

43

Nil

360

5

31

7.13

296

95

0.4

130

900

170

126

39

0.2

350

6

30

6.91

520

235

0.2

260

1500

349.9

170.1

52

0.1

450

7

32

7.5

184

45

0.4

64

500

99.9

84.1

34

Nil

280

8

30

6.7

440

145

0.5

200

1000

366.6

73.4

38

0.2

310

9

31

7.5

416

120

0.4

200

1000

133.32

282.68

44

0.1

400

10

31

7.47

192

45

0.3

40

500

83.325

108.67

30

0.2

290

11

31

7.14

380

105

0.6

184

900

206.646

173.35

34

Nil

296

12

34

7.27

400

95

0.4

140

900

183.315

216.68

37

Nil

400

13

30

7.78

320

155

0.2

120

900

99.99

220.01

49

0.1

430

14

30

7.13

460

265

0.2

360

1200

383.2

76.8

48

0.2

380

15

32

7.37

320

135

0.2

150

1000

209.97

110.1

49

0.1

420

16

29

8.25

200

120

0.1

110

700

89.991

110.009

46

0.2

316

17

31

7.45

352

120

0.2

160

1100

105

247

45

Nil

472

18

33

6.43

368

135

0.2

140

800

120

248

48

Nil

184

19

31

7.71

300

145

0.2

184

700

60

240

50

Nil

424

20

31

6.86

248

65

0.2

86

700

30

198

36

Nil

294

21

32

7.26

540

220

0.3

330

1400

240

300

51

Nil

296

22

32

7.2

472

160

0.2

130

1100

201

270

41

Nil

326

23

31

7.18

300

160

0.2

160

1100

80

220

43

Nil

464

24

32

7.7

380

120

0.2

110

1000

85

305

36

Nil

382

25

31

6.66

480

180

0.2

170

1300

102

380

36

Nil

370

26

31

6.6

300

80

0.1

120

700

60

240

26

Nil

200

27

32

6.85

890

130

0.4

216

1700

200

684

40

Nil

428

28

30

6.85

300

50

0.1

60

1000

50

250

26

Nil

256

29

30

6.9

380

140

0.2

148

1200

70

310

48

Nil

516

30

30

7.5

520

150

0.2

150

1200

205

315

34

Nil

380

31

32

6.84

600

200

0.2

220

1300

240

360

47

Nil

482

32

30

7.59

240

20

0.2

24

500

40

200

34

Nil

308

33

32

6.83

640

230

0.1

144

1600

210

430

39

Nil

512

34

31

7.11

560

220

0.1

260

1500

160

400

47

Nil

454

35

31

7.33

320

60

0.2

104

800

60

26

35

Nil

324

36

31

6.32

800

70

0.2

380

1600

70

550

39

Nil

320

37

32

6.67

280

80

0.1

42

700

80

248

29

Nil

280

38

30

6.65

400

190

0.1

44

900

190

240

27

Nil

272

39

30

6.42

270

70

0.1

136

700

70

340

27

Nil

202

40

30

6.69

300

85

0.1

40

600

85

220

22

Nil

184

41

30

6.8

260

80

0.1

44

500

80

222

22

Nil

174

42

30

6.51

390

180

0.1

40

900

180

215

27

Nil

264

43

32

7.06

260

105

0.2

120

800

105

304

31

Nil

292

44

31

7.2

400

155

0.2

40

800

155

216

29

Nil

270

45

31

7.15

440

250

0.2

90

1100

250

325

32

Nil

300

46

31

7.06

360

102

0.2

180

900

102

345

36

Nil

266

47

31

7.42

640

120

0.1

96

1200

120

308

36

Nil

380

48

30

6.97

300

200

0.1

284

1100

200

400

41

Nil

274

49

30

7.52

320

97

0.1

104

800

97

350

36

Nil

310

50

30

7.02

560

190

0.1

252

1400

190

380

41

Nil

350

MIN

29

6.32

172

20

0.1

40

500

30

26

22

0.0

174

MAX

33.5

8.25

890

265

0.6

380

1700

383.2

684

52

0.2

516

Mean

31.05

7.123

391.08

131.78

0.23

148.32

980

147.027

252.24

37.62

0.145

332.04

SD

1.089

0.435

149.74

58.149

0.135

84.717

309.706

84.640

123.09

7.917

0.052

89.65

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3 RESULTS AND DISCUSSION

3.1.1 pH

pH is one of the most important operational water quality parameters with the optimum pH required often being in the range of 7.0-8.5. The maximum permissible limit for pH in drinking water as given by the WHO is 8.5. The values of pH in the groundwater samples collected varied from 6.32 to 8.25 with an average value of
7.12 (Table 3). This shows that the quality of groundwater
of the study area is within the desirable limit. Spatial distributions of pH concentrations are shown in Figure.4a.

3.1.2 Electrical Conductivity (EC)

Electrical Conductivity (EC) of water at 30°C is due to the presence of various dissolved salts. The EC varies widely and ranges between 1135 and 1999 µS/cm at
30°C with a mean of 1567 µS/cm. Knowing that the maximum limit of EC in drinking water is prescribed as
1,500 µS/cm at 30°C the interpreted water quality with
respect to EC indicates that more than 98% of the study
area lies in maximum permissible limit for drinking water
purposes. The spatial distribution of EC concentrations are shown in Figure.4b.

3.1.3 Total Dissolved Solids (TDS)

Concentration of dissolved solids in groundwater decides its applicability for drinking, irrigation or industrial purposes. The concentration of dissolved matter in water is given by the weight of the material on evaporation of water to dryness up to a temperature of 1800C. The values are expressed in mg/l. The major constituents of TDS include Bicarbonates (HCO3)
Hardness in water is caused primarily by the presence of carbonates and bicarbonates of calcium and magnesium, sulphates, chlorides and nitrates. Total hardness is a measure of calcium (Ca2+) and magnesium (Mg2+) content in water and is expressed as equivalent of CaCo3. Water with a hardness of less than 75 mg/l is considered as soft. Hardness of 75-150 mg/l is not objectionable for most purposes. Minimum total hardness of 172 mg/l (Table 3) and maximum value of 890 mg/l . In general, hard waters are originates in areas where top soil is thick and limestone formation is present. Hard waters cause excessive consumption of soap used for cleaning purpose. Lathering does not take place until all hardness ions precipitate out. This precipitate adheres to surfaced of tubes, sinks, dish washer and may stain clothing. The spatial distributions of TH concentrations are shown in Figure.4d.
Sulphates (SO4

) and Chlorides (Cl ) of Calcium,

2+ -

Magnesium, Sodium and Silica. Groundwater containing more than 1000 mg/l of total dissolved solids is generally referred as brackish water. In the study area, the TDS amount ranges from 500 mg/l to 1700 mg/l with an average of 1000 mg/l (Table 3). About 48% of the water samples fall under higher solids content often has a laxative and sometimes reverse effect upon people whose bodies are not adjusted to them. The spatial distribution of TDS concentrations are shown in Figure.4c.

3.1.4 Total Hardness (TH)

Figure 4: Spatial distribution of a. pH, b. EC, c. TDS, d. TH

3.1.5 Sulphate (So4)

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Sulphates occur in natural waters at concentration up 50 mg/l. concentration of 1000 mg/l can found in water having contact with certain geological formations such as concentrations of sulphate may be due to the presence of sulphide ore bodies like pyrite, lignite and coal. Rain water has quite high concentration of sulphates particularly in areas with high atmospheric pollution. Higher concentration of sodium sulphate in water can cause malfunctioning of the alimentary canal. The recommended upper limit is 200 mg/l in water intended to human consumption. Sulphate concentration ranges from 20 mg/l to 265.4 mg/l. The spatial distribution of chloride concentrations are shown in Figure.5a

3.1.6 Chloride (Cl)

Chloride is present in all natural waters at greatly varying concentration depending on the geochemical conditions. Major sources of chloride in groundwater are the constituents of igneous and metamorphic rocks like gneisse and granite etc. Because of sewerage disposal and leaching of saline residues in the soil, abnormal chloride concentrations may occur. Chlorides can only be removed by reverse osmosis process and electrolysis. Water quality analysis of the samples collected indicates that the chloride concentration ranges from 40 mg/l to 380 mg/l. The spatial distribution of chloride concentrations are shown in Figure.5b

3.1.7 Bicarbonates (HCO3)

Alkalinity is caused due to the presence of carbonates, bicarbonates and hydroxides of calcium, magnesium, potassium and sodium. Calcium carbonate is the most usual constituent that causes alkalinity. Bicarbonate is expressed in mg/l as caco3 and the limit for drinking water is 100 mg/l as caco3. Total Bicarbonate in the groundwater in the basin ranges between 174 mg/l to
516 mg/l (Table 3). Excess bicarbonate in water is harmful
for irrigation which leads to soil damage and reduce crop yield. Water having bicarbonate less than 100 mg/l as caco3 is desirable for domestic consumption. High alkalinity in natural waters will favour of producers (algae and phytoplankton groups) The spatial distribution of bicarbonate concentrations are shown in Figure.5c.

Figure 5: Spatial distribution of a. sulphate, b. chlorides, c.

bicarbonate

3.1.8 Sodium (Na+)

Major source of sodium content in the ground water is due to presence of salts. Desirable limit of sodium content in the ground water is 200 mg/l . Sodium in the ground water basin ranges between 22 mg/l to 52 mg/l. Spatial distribution of Sodium concentrations are shown in Figure 6a.

3.1.9 Calcium (Ca 2+ )

Calcium occurs in water mainly due to the presence of limestone, gypsum, dolomite and gypsiferrous minerals. Permissible limit of calcium is 75 mg/l. Calcium concentration ranges from 30 mg/l to 383.2 mg/l. The spatial distribution of calcium concentrations are shown in Figure.6b.

3.1.10 Magnesium (Mg 2+)

Magnesium occurs in water mainly due to the presence of olivine, biotite, augite and talc minerals. Permissible limit of magnesium is 30 mg/l. Water quality analysis of the samples collected indicates that the magnesium concentration ranges from 26 mg/l to 684 mg/l. The spatial distribution of magnesium concentrations are shown in Figure.6c.

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understand the status of the groundwater quality; and to have the opportunity for better use in future as well. The overall view of the WQI (Table 4) of the present study zone shows a higher WQI. But, only eleven locations had a satisfactory result with a WQI below 100. This study demonstrates that the use of GIS and WQI methods could provide useful information for water quality assessment.

Figure 6: Spatial distribution of a. sodium, b. calcium, c. magnesium

Figure 7: Spatial distribution of Water Quality Index

4 .0 Conclusions

In the present investigation, an attempt was made to evaluate and to map the groundwater quality of Upper Pincha Basin. GIS makes the groundwater quality maps in an easily understood format. It is shown that the majority of the samples presented a pH value within the maximum permissible limit; water quality with respect to EC indicates that reflected a pH value is within the limit. The TDS value of Upper Pincha Basin is very high which results it is brackish water. In our study, spatial distribution map of TH shows that a majority of the groundwater samples falls in the very hard category causes excessive consumption of soap used for cleaning purpose. Lathering does not take place until all the ions causing hardness are precipitated. This precipitate adheres to surfaced of tubes, sinks, dish washer and may stain clothing. The predominant cation trend in Upper Pincha Basin is Ca 2+
>Mg 2+ >Na +. Almost all groundwater samples exceed the maximum permissible limit of magnesium; Sodium(Na) concentrations are within the maximum permissible limit. The abundance of the major anions in Upper Pincha Basin is in the following order: HCO3- >Cl->SO4 - . HCO3 concentration is above the maximum permissible limit. Excess bicarbonate in water is harmful for irrigation which leads to soil damage and reduce crop yield.
The Water Quality Index is a very useful and an efficient tool to summarize and to report on the monitoring data to the decision makers in order to be able to

Table 4. Water Quality Index Values for different samples

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30

166.99

Poor

31

194.89

Poor

32

88.772

Good

33

214.292

Very poor

34

200.689

Very poor

35

76.77

Good

36

230.492

Very poor

37

107.194

Poor

38

127.89

Poor

39

121.703

Poor

40

95.476

Good

41

90.135

Good

42

121.254

Poor

43

126.645

Poor

44

118.745

Poor

45

161.615

Poor

46

149.217

Poor

47

162.851

Poor

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