an appraisal of groundwater chemistry … appraisal of groundwater chemistry and interpretation of...

International Journal of Environmental Science and Ecotechnology1(1) January-June 2011; pp. 67-80

AN APPRAISAL OF GROUNDWATER CHEMISTRY AND INTERPRETATION OF HYDROCHEMICAL FACIES — A CASE STUDY OF BOMMANAHALLI INDUSTRIAL AREA INBANGALORE, INDIA

B.S. ShankarDepartment of Civil Engineering, East Point College of Engineering and Technology, Bidarahalli, VirgonagarPost, Bangalore-560049, Karnataka, India. E-mail: [email protected]

Abstract: The present study aims at the evaluation of hydrochemistry and the interpretation ofhydrochemical facies for the groundwaters of Bommanahalli industrial area of Bangalore using a computertechnique. Hydrochemical facies represent distinct zones with definite cation and anion concentrationsand depicts the diagnostic chemical characteristics of water in various parts of the system. Hydrochemicalfacies reflect the effects of chemical processes occurring between the minerals with in the lithologicalframework and groundwater. In this connection, 60 groundwater samples (30 each in the pre andpost-monsoon seasons of 2008) have been drawn from the area and subjected to a comprehensive physico-chemical analysis. From the results of the study, a detailed assessment of the existing hydrochemistry ofits ground waters has been made and hydrochemical facies have been derived and discussed for all thesamples. Further, their suitability for different purposes based on the above has been highlighted.

Keywords: Groundwater, Hydrochemical facies, Potability, Salinity, Sodium hazard.

1. INTRODUCTION

The ionic quality changes as water descends into the soil because of its interaction with the rocksubstrate. Groundwaters in a system that differ in their chemical composition are often describedas hydro-chemical facies. The concept of hydrochemical facies is to understand the chemicalcharacteristics of groundwater and has been used by many workers (Back and Sanshaw, 1965;Davis and Dewiest, 1966; Walton, 1970). ‘They pointed out that facies reflect the effects ofchemical processes occurring between the minerals within the lithological framework andgroundwater. In general, the hydrochemical facies at a place is influenced by the geology andthe distribution of facies by the hydrological control’.

Mere discussions of the physical and chemical characteristics of groundwater do not yielda comprehensive account of the waters. One element may appear to be high, while the otherlow, but the interaction of a high cation with that of a low anion may produce a specific qualityof water that may be fit for domestic or agricultural use or may not be of use for any specificpurpose. Hence an integrated and composite approach of the entire physico-chemical characte-ristic of the samples would yield a better and concise output of the data (Meenakumari, 2004).

To overcome the adverse effects due to the presence of higher concentrations of dissolvedions, the health hazards they pose and also for effective planning, management and utilizationof groundwater resources, it is essential to know the associated hydrogeochemical processes

© International Science Press

mailto:[email protected]:

68 / INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE & ECOTECHNOLOGY

contributing to increase the salinity in the groundwater. Once the processes are evaluated, itmay easy for managers to take the remedial measures for mitigating the degree of salinity inthe groundwater and thereby improving the standards of living conditions (Subba Rao, 2008).

Literature suggests that little work on this aspect has so far been done in India (Durvey etal. 1991; Agrawal and Jagetia 1997; Niranjan Babu et al. 1997; Majumdar and Gupta 2000;Khurshid et al. 2002; Sreedevi 2004; Subba Rao and John Devadas 2005). An attempt is,therefore, made in this paper to examine the associated hydrogeochemical processes.

2. MATERIALS AND METHODS

2.1 Computer Techniques for Evaluation of Facies

There are many systems of classifying groundwater as hydrochemical facies. Each system hasa specific formula for its evaluation. To obtain results by manual calculations would be tootedious and the possibility of committing errors is also high. Therefore the entire samplingdata has been processed using the computer programme “HYCH” (Hydrochemical FaciesClasses Software) in BASIC language, developed by Balasubramanian et al. (1991). The HYCHflow chart is shown in Fig. 1.

The following facies have been derived and discussed

1. Handa’s Classification (1964)

2. Schoellar’s water type (1965)

3. Stufyzand’s classification (1989)

4. USSL, United States Salinity Laboratory System, (Wilcox, 1955)

5. Classification based on Sodium Absorption Ratio (Todd, 1959)

6. Classification based on Residual Sodium Carbonate (Richards, 1954)

7. Classification based on Corrosivity Ratio, CR (Ryzner, 1944)

8. Classification based on indices of Base Exchange (Schoellar, 1967)

9. Classification based on Gibb’s plot (1970)

10. Classification based on Permeability index (Doneen, 1962)

2.2 Data Input and Programme Description

This programme utilizes the groundwater quality parameters such as pH, EC, TDS, Oxidation-Reduction Potential (ORP), DO, Temperature and the concentrations of Ca, Mg, Na, K, HCO

3,

CO3, Cl, NO

3 and SO

4. However, ORP and DO have been kept constant at laboratory temperature

and the other parameters are utilized in this programme. There is an input provision to print theinput data along with the output results. Such output data sets have been obtained for all the 60samples (30 samples each, during pre and post- monsoon periods of 2008), but only theconsolidated tables including different chemical characteristics of all the groundwater samplesfor pre and post-monsoon periods have been provided in Table 1.

AN APPRAISAL OF GROUNDWATER CHEMISTRY AND INTERPRETATION OF HYDRO ... / 69

Figure 1: Flow Chart of HYCH Programme

70 / INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE & ECOTECHNOLOGYT

able

1 R

esul

ts o

f H

ydro

chem

ical

Fac

ies

for

Gro

undw

ater

No

Han

da’s

Scho

elle

rSt

ufyz

and

USS

LSA

RR

SCC

.R

IB

E

Gib

b’s

D

onee

n’s

P.I

Cla

ssW

ater

Typ

eTy

pe (

Mai

n)

CLA

1C

LA

2P

lot

Pre

Pos

tP

reP

ost

Pre

Pos

tP

reP

ost

Pre

Pos

tP

reP

ost

Pre

Pos

tP

reP

ost

Pre

Pos

tP

reP

ost

Pre

Pos

t

1A

2C3S

1A

2C3S

1II

III

If

fC

3S1

C3S

10.

770.

75–4

.56

–5.4

71.

291.

59 0

.73

0.7

5 0

.64

0.72

RI

RI

35.0

132

.61

2A

2C3S

1A

2C3S

1II

III

If

fC

3S1

C3S

10.

280.

37–5

.21

–5.6

01.

261.

38 0

.89

0.8

7 0

.75

0.84

RI

RI

25.8

626

.44

3A

2C3S

1A

2C3S

1II

III

If

BC

3S1

C3S

11.

221.

00–5

.59

–5.1

61.

652.

19 0

.66

0.6

5 0

.69

–0.8

8R

IR

I37

.69

42.6

14

A1C

3S1

A2C

3S1

III

III

FF

C3S

1C

3S1

1.84

1.88

–1.9

4–3

.05

0.70

0.89

–0.0

6 0

.00

–0.0

30.

00R

IR

I54

.25

51.1

85

B2C

2S1

A1C

3S1

III

III

FF

C2S

1C

2S1

2.72

2.49

–0.9

2–0

.87

0.58

0.83

–0.9

1–0

.54

–0.3

7–0

.26

RI

RI

76.6

169

.67

6A

2C3S

1A

2C3S

1II

III

If

fC

3S1

C3S

11.

351.

42–3

.88

–4.6

11.

431.

89 0

.53

0.5

6 0

.44

0.54

RI

RI

44.0

443

.04

7A

1C3S

1A

2C3S

1II

III

IF

FC

3S1

C3S

11.

251.

26–1

.22

–2.0

40.

630.

84 0

.35

0.4

3 0

.19

0.29

RI

RI

50.8

449

.02

8A

2C3S

1A

2C3S

1II

III

If

FC

3S1

C3S

12.

342.

51–1

.02

–2.3

70.

880.

93 0

.07

–0.2

1 0

.05

–0.1

3R

IR

I61

.66

58.6

19

A3C

2S1

A3C

2S1

III

III

Ff

C2S

1C

2S1

2.40

2.79

0.2

5–1

.43

0.73

1.44

–0.5

1–0

.42

–0.2

2–0

.29

RI

RI

82.9

071

.35

10A

2C3S

1A

2C3S

1II

III

If

fC

3S1

C3S

13.

003.

04–8

.11

–10.

312.

373.

22 0

.01

0.0

4 0

.01

0.03

RI

RI

48.1

045

.23

11A

1C3S

1A

2C3S

1II

III

IF

FC

3S1

C3S

11.

191.

09–0

.08

–2.5

20.

590.

90 0

.09

0.2

1 0

.02

0.07

RI

RI

52.8

845

.07

12A

1C3S

1A

2C3S

1II

III

IF

FC

3S1

C3S

11.

411.

39–2

.70

–3.2

20.

771.

00 0

.05

0.1

9 0

.02

0.84

RI

RI

49.4

647

.64

13A

2C3S

1A

2C3S

1II

III

If

fC

3S1

C4S

11.

340.

98–1

.23

–1.8

40.

840.

96 0

.47

0.8

4 0

.36

0.54

RI

RI

54.0

047

.21

14A

2C3S

1A

2C3S

1II

III

If

fC

3S1

C3S

13.

022.

74–2

.66

–2.5

50.

941.

15–0

.26

–0.0

2–0

.15

–0.1

4R

IR

I58

.05

58.2

615

A2C

4S2

A2C

3S1

III

III

BB

C3S

1C

3S1

3.50

3.04

–5.9

1–5

.95

1.33

1.12

0.0

2 0

.04

0.1

40.

02R

IE

VP

51.9

148

.22

16A

2C3S

1A

2C3S

1I

III

BB

C3S

1C

3S1

1.57

1.51

–5.6

1–8

.49

1.35

1.74

0.6

8 0

.70

0.9

31.

17R

IR

I38

.53

34.3

817

A2C

3S1

A2C

3S1

IVIV

BB

C3S

1C

3S1

2.69

2.84

–3.9

6–4

.96

1.59

2.04

0.4

5 0

.46

0.6

30.

75R

IR

I53

.15

52.0

818

A2C

3S1

A2C

3S1

III

III

ff

C3S

1C

3S1

1.19

1.23

–4.9

1–6

.00

0.95

1.14

0.4

8 0

.50

0.3

80.

46R

IR

I38

.68

36.9

519

A2C

3S1

A2C

3S1

III

III

BB

C3S

1C

3S1

1.13

0.94

–5.8

9–8

.09

1.92

2.97

0.7

6 0

.84

1.6

52.

77R

IR

I36

.09

29.8

920

A2C

5S2

A2C

5S2

III

III

bB

C4S

1C

3S1

1.58

1.47

–30.

16–3

3.19

16.7

719

.98

0.8

5 0

.87

7.5

77.

48R

IR

I20

.19

18.5

221

A2C

5S2

A2C

5S2

III

III

bb

C4S

1C

4S1

2.58

2.72

–18.

6620

.97

10.9

612

.78

0.7

1 0

.73

3.0

33.

32R

IR

I33

.66

33.1

322

A2C

3S1

A2C

3S1

III

III

FF

C3S

1C

3S1

1.75

1.79

–3.9

3–5

.27

0.87

0.99

0.0

7 0

.06

0.0

40.

04R

IR

I47

.67

44.4

223

A3C

4S3

A3C

4S3

III

III

BB

C4S

2C

4S2

6.53

6.34

–3.8

1–4

.86

2.30

2.91

–0.2

7–0

.12

–0.1

8–0

.09

RI

RI

68.8

767

.43

24A

2C5S

2A

2C5S

2II

III

Ib

bC

4S1

C4S

12.

572.

56–1

9.75

–21.

296.

938.

42 0

.69

0.74

2.0

52.

54R

IR

I33

.32

32.2

725

A2C

3S1

A2C

3S1

III

III

ff

C3S

1C

3S1

4.03

3.96

–5.1

7

5.1

52.

132.

11–0

.37

–0.3

8–0

.21

–0.2

2R

IR

I59

.90

59.6

826

B1C

3S1

A1C

3S1

III

IF

fC

3S1

C3S

12.

361.

96 1

.15

–0.9

50.

590.

82–0

.01

–0.3

0–0

.01

0.20

RI

RI

64.6

260

.14

27A

1C2S

1A

1C2S

1II

III

IF

FC

2S1

C2S

11.

411.

50–0

.66

–1.0

40.

600.

71–0

.76

–0.6

9–0

.23

–0.2

3R

IR

I68

.60

64.6

728

A2C

3S1

A2C

3S1

III

III

BB

C3S

1C

3S1

1.41

1.46

–78.

00–7

.91

1.65

1.88

0.6

1 0

.62

0.5

20.

62R

IR

I37

.20

35.1

329

A2C

5S2

A2C

5S2

III

III

BB

C4S

2C

4S2

4.05

4.25

–11.

55–1

3.65

1.88

2.35

0.0

4 0

.03

0.0

30.

03R

IR

I48

.21

47.6

430

A2C

3S1

A2C

3S1

III

III

ff

C3S

1C

3S1

2.52

2.64

–6.4

3–7

.27

1.80

2.18

0.2

1 0

.23

0.1

90.

22R

IR

I47

.89

47.2

5


2.3 Details of The Study Area

The Bommanahalli City Municipal Corporation (CMC) is a cluster of villages located in betweenSarjapur road and Kanakapura road of Bangalore city in Karnataka. The area covers 43.57Sq. km and has a population of around 3.5 lakh. It has a large percentage of migrants whocame to Bangalore in the wake of the software boom in the 1990’s. Lying adjacent to the westof the Bangalore- Hosur road and adjacent to the IT corridor, the area has a number of industries,corporate offices of leading software companies and a few upscale residential layouts. Drinkingwater from the CMC borewells has become a scarcity and there is a thriving private market forwater, with the people paying huge amount to private borewell owners to meet their needs.There are several areas where the sewage and drainage have merged and the huge number ofindustries in the area is blatantly disposing off their untreated/improperly treated effluents,which have been steadily making their way into the already depleted and contaminatedgroundwaters of the area.

2.4 Collection of Sample and Analysis

Sixty water samples (thirty in each season) were collected from both the borewells and openwells in the industrial area during March and October periods of 2008 in two litre PVC containersand sealed and were analyzed for the major physico-chemical parameters in the lab .The locationmap of the study area showing the sampling locations is shown in Fig. 2. The physical parameterssuch as pH and electrical Conductivity were determined in the field at the time of samplecollection. The chemical characteristics including metals were determined as per the Standardmethods for examination of water and wastewater in accordance with the ‘American PublicHealth Association’ (APHA, 2002).

3. RESULTS AND DISCUSSION

Based on the analysis of groundwater samples, the following hydrochemical facies have beenderived and explained. The details of all the hydrochemical facies for the groundwater sampleshave been presented in Table 1. The groundwater facies have been presented below.

3.1 Handa’s System of Classifying Groundwater

Utilizing Handa’s system of classification two facies, namely groundwater hardness andgroundwater salinity- sodium hazard have been developed (Handa, 1964) for the groundwatersof the study area and have been briefly discussed below.

3.1.1 Groundwater Hardness

Based on Handa’s system of classification, the groundwater has been classified into permanent(A

1, A

2, A

3) and temporary hard water (B

1, B

2, B

3). A

1 to A

3 indicates permanent hardness based

on the richness of calcium and magnesium and its relation to bicarbonates, while B1 to B

3

indicates temporary hardness based on the same ions used in the classification of permanenthardness. In the present study, it is found that water belonging to permanent hardness occupies


a major part of the study areas, with 28 out of the 30 samples, i.e. 93.33% of the samples fall inthis category during pre-monsoon and all the 30 samples (100%) fall in this permanent categorypost-monsoon seasons.

Figure 2: Location map of Bommanahalli industrial area showing the sampling stations.

3.1.2 Groundwater Salinity-sodium Hazard

Based on the degree of salinity-sodium hazard, the groundwater has been classified intocategories (C

1, C

2, C

3, C

4, C

5) and (S

1, S

2, S

3, S

4, S

5). Among these, all the waters up to C

3 could

be suitably used for crops, where as C4 type could be used to some extent for salt-tolerant


crops and the extreme salinity class C5 is not suitable for any crop cultivation. Based on this

classification, 80% and 83.33% of the samples fall under safe category for crop cultivationduring pre and post-monsoon seasons respectively.

3.2 Schoeller’s System of Classification

Schoeller based on the movement of water into the soil proposed this classification, which ismainly based on the percolation of water into the soil and changes in the anion concentration(Schoeller, 1967).

Schoeller has pointed out that the first and foremost type of water is one in which

γHCO3 > γSO

4Type I

As concentration increases, the above relation changes to

γSO4 > γCl Type II

Still at a higher concentration, the water may change to

γCl > γSO4 > γCO

3Type III

And in the final stage, γCl > γSO4 > γCO

3 and

γNa > γMgSO4> γCa Type IV

where γ represents the epm (equivalents per million) concentration of ions.

The groundwater types prevailing in this region are given in Table 2a and 2b, accordingto which 27 out of 30 samples in pre-monsoon and 29 out of 30 samples in post-monsoon fallunder type III, thus the groundwaters of the area indicate a total dominance of Type III class.

Table 2bClassification of Samples Based on Schoeller Type During Post-monsoon

Total number of Schoeller type Dominance of Schoeller type

I II III IV

Nil Nil 29 01 Type III

Table 2aClassification of Samples Based on Schoeller Type During Pre-monsoon

Total number of Schoeller type Dominance of Schoeller type

I II III IV

2 Nil 27 1 Type III

3.3 Indices of Base Exchange

Knowledge of the changes brought about in the chemical composition of the groundwaterduring its travel underground is essential (Sastri, 1994). Schoeller (1967) proposed an index of


base exchange called Chloro-alkaline indices, CLA1 and CLA2 to indicate the exchange ofions between the groundwater and the host environment. If there is an exchange of Na+ and K+

from water with Ca2+ and Mg2+ in the rock, the exchange is designated as direct exchange andif the exchange is reversible ,that is, Ca2+ and Mg2+ of the rock exchanging with the Na+ and K+

of water, it is known as reverse exchange. This may be represented as a reversible chemicalreaction:

2 2DirectNa K Ca Mg+ + + ++ → +

Water RockReverse

←

These indices are determined based on the exchange phenomenon of Cl–, Na+ and K+ andthe use of 2

4 3 3SO , HCO , CO−− − − and3NO− (anions) expressed as epm values. These in turn determine

the quality of water. In some, the capacity exchange of ions is low and in others, it is high.

CLA1 is determined as Cl (Na K)

Cl

− +

and CLA2 as4 3 3

Cl (Na K)

SO HCO NO

− ++ +

The values indicate the nature of rocks. If the values of the indices are positive, it denotes adirect exchange, while in case of reverse exchange, the indices are negative. ‘Negative valuesindicate that the water samples do not have long residence time in the aquifers and vice-versa’(Freeze and Cherry, 1979; Fetter, 1980). During both the pre-monsoon and post-monsoon periods,8 samples had negative indices and 22 samples have positive indices, indicating that the majorportion of samples in the study area have long residence time in the aquifer.

4. STUFYZAND’S CLASSIFICATION

The hydrochemistry of groundwater of different environments could be assessed by usingStufyzand’s classification. This system helps in the determination of the type of water that belongsto the main type or subtype (Stufyzand, 1989). The main criterion used in this system is chloridity.The classification based on chloride content for the determination of main type is indicatedin Table 3.

Table 3Stufyzand’s Classification Based on Chloride During Pre and Post-monsoon

Main type Code Chloride, mg/L

Extremely fresh G < 5Very fresh or Oligohaline G 5 to 30Fresh F 30 to 150Fresh- brackish f 150 to 300Brackish B 300 to 1000Brackish- salt b 1000 to 10,000Salt S 10,000 to 20,000Hyperhaline H > 20,000


Based on this category, 40% the groundwater samples of the area fall under the fresh-brackish category, 23% under brackish category and 27% under fresh category duringpre-monsoon, while 33% of the samples fall under fresh-brackish category, 27% under brackishcategory and 30% under fresh category during post- monsoon season as indicated in Table 3a.

Table 3aClassification of groundwater as per Stufyzand

Number of samples under main Type

Fresh Fresh-Brackish Brackish Brackish to salt

Pre Post Pre Post Pre Post Pre Post

9 9 11 10 7 8 3 3

5. GROUNDWATER TYPES BASED ON SODIUM HAZARDAND SALINITY (USSL, WILCOX, 1955)

Apart from classifying groundwaters for domestic or potable use, many systems have alsobeen used to classify the water for irrigation purposes. The main criteria here are the sodiumhazard and salinity. Sodium concentration is important in classifying irrigation water becausesodium reacts with soil to reduce its permeability (Janardhana Raju, 2007). One such system isthe one developed by the United States Regional Salinity Laboratory’ (USSL, Wilcox, 1955).The classification for groundwaters is grouped under 16 classes. The Sodium Absorption Ratio(SAR) is calculated using the formula,

SAR(Ca Mg) / 2

Na=+

where the concentrations are expressed as meq/L. This represents an index for the sodiumhazard (S). Also, the salinity hazard (C) is calculated using the electrical conductivity (EC) asan index at 25°C. The C values indicate salinity and range from C1 to C4 that is, low salinitywaters to very high salinity waters. Low to medium salinity waters (C1 and C2) can be usedfor irrigation. The sodium hazard from S1 to S4 and low sodium waters only can be used forirrigation (Wilcox, 1955). The USSL plot for the groundwaters of the study area is presentedin Fig. 3. Based on USSL classification, it is found that 73.33% of the samples fall under C3S1category during both pre- and post- monsoon seasons as shown in Table 4.

Table 4Dominant Groundwater Types Based on USSL Classification

Type

C3S1 C2S1 C4S1 C4S2

Pre Post Pre Post Pre Post Pre Post

22 22 3 3 3 3 2 2


6. GROUNDWATER CLASSIFICATION BASED ON SODIUM ABSORPTIONRATIO, SAR (TODD, 1959)

Another important chemical parameter for judging the degree of suitability of water for irrigationis sodium content or alkali hazard, which is expressed as Sodium Absorption Ratio. The SARis computed, where the ion concentrations are expressed in meq/l. There is a close relationshipbetween SAR values in irrigation water and the extent to which Na+ is absorbed by soils. ‘Ifwater used for irrigation is high in Na+ and low in Ca2+, the ion-exchange complex may becomesaturated with Na+, which destroys soil structure, because of dispersion of clay particles. As aresult, the soils tend to become deflocculated and relatively impermeable. Such soils can bevery difficult to cultivate’ (Todd, 1959). The sodium hazard is expressed in terms of classificationof irrigation water as low (S1: < 10) and class excellent, medium (S2: 10 to 18) and class good,high (S3: 18 to 26) and class fair and very high (S4 : > 26) and class poor. The higher the SARvalues in the water, the greater the risk of sodium. Based on this category, all the 30 samples inboth the pre-monsoon as well as post-monsoon seasons have a SAR value of less than 10 andthus fall under excellent category with respect to use for irrigation.

7. GROUNDWATER CLASSIFICATION BASED ONRESIDUAL SODIUM CARBONATE (RSC)

The suitability of water for irrigation can also be determined by determining the RSC. Usuallyanionic concentration of bicarbonate and carbonate determine the efficiency of water. TheRSC is computed using the equation,

Figure 3: USSL Plot for the Groundwaters of Bommanahalli Industrial Area


RSC = 2 2 23(CO HCO3 ) (Ca Mg )− − + ++ − +

Where, the ions are expressed in meq/L or epm.

Richards proposed a set of values for the suitability index (Richards, 1954). Table 5 presentsthese values along with the number of samples falling in a particular range. In the presentstudy, it is found that all the samples examined have RSC values less than 1.25 and are consideredsafe for irrigation purposes. This pattern is observed both during pre-monsoon as well as post-monsoon seasons of the study.

Table 5Classification of Groundwater Samples as Per RSC (Richards, 1954)

RSC (epm) Suitability/ class No of samples No of samples inin pre-monsoon post-monsoon

> 2.5 Unsuitable for irrigation Nil Nil1.25 – 2.5 Marginally suitable Nil Nil< 1.25 Safe 30 30

8. MECHANISM CONTROLLING GROUNDWATERCHEMISTRY (GIBBS, 1970)

The decomposition of rocks adds to the composition of groundwater as it seeps down. It maybecome more and more concentrated with respect to the cation and anionic composition, andtherefore becomes the main criteria for controlling the groundwater. The values of {(Na + K)/(Na + K + Ca)}, and {(Cl / (Cl + HCO

3)} on X axis are plotted against the Total Dissolved

Solids (TDS) values and based on the position they occupy in the figure, they are classified asto which of the Rock dominant, evaporation process dominant, or the third type, precipitationdominance is in abundance (Gibbs, 1970). In the present study, during pre and post- monsoonseasons, all 30 and 29 samples out of the 30 groundwater samples analyzed respectively, are ofthe Rock Interaction (RI) or Rock Dominance (RD) type.

9. DONEEN’S (1962) CLASSIFICATION OF GROUNDWATERS(PERMEABILITY INDEX)

Taking into account the salinity of water, its permeability and toxicity, Doneen modified theclassification proposed by the U.S. Soil Salinity diagram (Doneen, 1962). Chlorides of calcium,magnesium and sodium and bicarbonates of sodium are the main causes of salinity andaccumulate in the soil. The Doneen’s classification involves the calculation of a permeabilityindex as:

P.I =3Na HCO

100Ca Mg Na

+×

+ +


These permeability index values obtained are plotted against TDS values and dependingupon the position they occupy, they are classified as Class I, Class II and Class III. Watersgrouped in Class I and Class II have greater permeability value and are within the zone ofgood or moderate waters for irrigation purposes, while Class III waters have poor agriculturalvalue. Classification of waters under the study area indicate that a majority are of Class II ,i.e.90% of the samples in pre-monsoon and 96.67% during post-monsoon are of class II as indicatedin Table 6.

Table 6Classification of Groundwaters Based on Doneen’s Permeability Index

Class I (PI >75) Class II (PI 25 - 75) Class III (PI < 25)

Pre Post Pre Post Pre Post

2 nil 27 29 1 1

10. CORROSIVITY RATIO (CR)

Corrosion is a phenomenon of interaction of metals with water resulting in its deterioration. Inthe water conveyance and distribution system, corrosion causes significant losses in the hydrauliccarrying capacity of pipes and fittings when poor quality water is transported. ‘An index toevaluate corrosive tendency of groundwater towards metallic pipes was proposed by (Ryzner,1944)’. Many workers have discussed the importance of corrosivity ratio (index) in groundwaterstudies. The index is calculated using the following formula:

Corrosivity ratio =4

3 3

(0.028 Cl 0.021 SO )

0.02 (HCO CO )

++

where all ionic values are expressed in ppm

Waters having a corrosivity ratio of less than 1 are considered non corrosive, while waterswith a corrosivity ratio of greater than 1 are considered corrosive. Thus waters with a CR < 1,could be transported by metallic pipelines, whereas for waters with a CR > 1, metallic pipes getcorroded and hence non corrosive PVC pipes have to be utilized. In the study area, 57% of thesamples in pre-monsoon and 70% of the samples in post-monsoon have a CR of more than 1 andhence corrosive in nature. They cannot be transported in metallic pipes.

11. CONCLUSION

1. In the present study, it is found that water belonging to permanent hardness occupies amajor part of the study area, with. 93.33% and 100% of the samples falling in thiscategory during pre-monsoon and post-monsoon seasons respectively. Based on thedegree of salinity- sodium hazard, 80% and 83.33% of the samples fall under safecategory for crop cultivation during pre and post-monsoon seasons respectively.

2. Based on the percolation of water into the soil and changes in the anion concentration,27 out of 30 samples in pre-monsoon and 29 out of 30 samples in post-monsoon fallunder type III, thus the groundwaters of the area indicate a total dominance of TypeIII class.


3. Based on the Chloro-alkaline indices, during both the pre-monsoon and post-monsoonperiods, 8 samples have negative indices and 22 samples have positive indices,indicating that the major portion of samples in the study area have long residence timein the aquifer.

4. According to the classification based on chloride content, , 40 % the groundwatersamples fall under the fresh-brackish category, 23% under brackish category and 27%under fresh category during pre-monsoon, while 33 % of the samples fall under fresh-brackish category, 27% under brackish category and 30% under fresh category duringpost- monsoon season.

5. Based on the Sodium Absorption Ratio, all the 30 samples in both the pre-monsoon aswell as post-monsoon seasons have a SAR value of less than 10 and thus fall underexcellent category with respect to use for irrigation.

6. Based on the mechanism controlling groundwater chemistry, all 30 samples duringpre -monsoon and 29 samples post- monsoon seasons are of the Rock Interaction (RI)or Rock Dominance (RD) type.

7. According to Doneen’s classification, based on the Permeability index, a majority ofthe groundwater samples fall under Class II, i.e. 90% of the samples in pre-monsoonand 96.67% during post-monsoon, signifying good or moderate waters for irrigationpurposes.

8. Based on the corrosivity ratio, 57 % of the samples in pre-monsoon and 70% of thesamples in post-monsoon have a CR of more than 1 and hence found to be corrosivein nature. They cannot be transported in metallic pipes.

9. The study has helped to improve understanding of hydro-geochemical characteristicsof the area for effective management and proper utilization of groundwater resourcesfor better living conditions of the people.

ACKNOWLEDGEMENTS

The author is extremely grateful to the management and Principal of East Point College ofEngineering and Technology, Bangalore, for the Support and encouragement provided to themduring the course of this work.

References

[1] Agrawal V., Jagetia M., 1997. “Hydrogeochemical Assessment of Groundwater Quality in Udaipur City,Rajasthan, India”. Proceedings of Dimensions of Environmental Stress in India (151-154), Departmentof Geology, The Maharaja Sayajirao University of Baroda, India.

[2] APHA, 2002. “Standard Methods for the Examination of Water and Wastewater”, Twentieth Edition,American Public and Health Association, Washington D.C.

[3] Back., Sanshaw., 1965. “Chemical Geohydrology”. In: Advances in Hydroscience (Ed.: Chow, V.T.).Academic Press, New York. pp. 49-109.

[4] Balasubramanian A., Subramanian S., Sastri J.C.V., 1991. “Hydro Chemical Facies Classes Software”,HYCH Basic Computer Programme for Hydrogeological Studies.


[5] Davis S.N., Dewiest R.J.M., 1966. “Investigating Groundwater Systems on Regional and National Scales”,Hydrogeology, John Wiley and Sons, New York. pp. 71- 128.

[6] Doneen L.D., 1962. “The Influence of Crop and Soil on Percolating Waters”. Proc. Biennial Conferenceon Groundwater Recharge, Geol. Soc, Amer. Bull. pp. 73- 75.

[7] Durvey V.S., Sharma L.L., Saini V.P., Sharma B.K., 1991. “Handbook on the Methodology of WaterQuality Assessment in India”. Rajasthan Agriculture University.

[8] Fetter C.W., 1980. “Applied Hydrogeology”, Merrill Pub. Comp., Columbus, Ohio. pp. 488.

[9] Freeze R.A., Cherry J.A., 1979. “Groundwater”. Prentice Hall Inc., New Jersey. pp. 604.

[10] Gibbs R.J., 1970. “Mechanisms Controlling World’s Water Chemistry”. Sci. 170, 1088-1090.

[11] Handa B.K., 1964. “Hydrogeochemical Processes in the Recent Sedimentary Basins”, Report, I.G.C.22nd Session, India, Part XIII, 126-141.

[12] Janardhana Raju N., 2007. “Hydrogeochemical Parameters for Assessment of Groundwater Quality inthe Upper Gunjanaeru River Basin”, Cuddapah District, Andhra Pradesh, South India. Environ. Geol.52, 1067-1074.

[13] Khurshid S.H., Hasan N., Zaheeruddin., 2002. “Water Quality Status and Environmental Hazards inParts of Yamuna-Karwan Sub-basin of Aligarh-Mathura District”, Uttar Pradesh. India. Journal of AppliedHydrology, 15, 30-37.

[14] Majumdar D., Gupta N., 2000. “Nitrate Pollution of Groundwater and Associated Human HealthDisorders”. Indian J. Environ. Health, 42, 28-39.

[15] Meenakumari H.R., 2004. “Groundwater Pollution with Special Reference to Open Wells in and AroundMysore City”, Karnataka, Ph.D., Dissertation, University of Mysore.

[16] Niranjan Babu P., Subba Rao N., Chandra Rao P., Prakasa Rao J., 1997. “Groundwater Quality and ItsImportance in the Land Developmental Programmes”. Indian J. Geol. 69, 305-312.

[17] Richards L.A., 1954. “Diagnosis and Improvement of Saline and Alkali Soils”, United States Departmentof Agriculture, Handbook. pp.60.

[18] Ryzner J.W., 1944. “A New Index for Determining the Amount of Calcium Carbonate Scale Formed byWater”. J. Amer. Water Works Assoc. 36, 472- 486.

[19] Sastri J.C.V., 1994. “Groundwater Chemical Quality in River Basins, Hydrogeochemical Facies andHydrogeochemical Modeling”. Lecture Notes-refresher Course Conducted by School of Earth Sciences.Bharathidasan University, Thiruchirapalli, Tamil Nadu, India.

[20] Schoeller H., 1967. “Quantitative Evaluation of Groundwater Resources”. Water Resources Series,UNESCO. 33, 44-52.

[21] Sreedevi P.D., 2004. “Groundwater Quality of Pageru River Basin”, Cuddapah District, Andhra Pradesh.J. Geol. Soc. India 64, 619-636.

[22] Stufyzand P.J., 1989. “A New Hydrochemical Classification of Water”. Proc. IAHS 3rd ScienceAssociation, Baltimore, USA. 10-19.

[23] Subba Rao N., 2008. “Factors Controlling the Salinity in Groundwater in Parts of Guntur District”,Andhra Pradesh, India. Environ. Monit. Assess. 138, 327-341.

[24] Subba Rao N., John Devadas, D., 2005. “Quality Criteria for Groundwater Use for Development of anArea”. J. Appl. Geochem. 7, 9-23.

[25] Todd D.K., 1959. “Groundwater Hydrology”. John Wiley and Sons Inc., New York. pp. 336.

[26] Walton W.C., 1970. “Selected Analytical Methods for Well and Aquifier Evaluation”. Illinois State WaterSurvey Bulletin, No.49, Groundwater Resource Evaluation, McGraw Hill, New York.

[27] Wilcox L.V., 1955. “Classification and Use of Irrigation Waters”, Circ, U.S. Dept. Agr., 969.

an appraisal of groundwater chemistry … appraisal of groundwater chemistry and interpretation of...

Documents