102

CHAPTER - 6

CLASSIFICATION OF GROUNDWATER AND ITS CHEMICAL

ATTRIBUTES FOR VARIOUS APPLICATIONS

6.1 GENERAL

Over the last 50 years, geochemistry is significantly contributing to field of

hydrogeology and has reformed our understanding that how geological, structural,

mineralogical and hydrological features affect the flow and chemistry of groundwater

systems (Glynn and Plumer, 2005). The principal component of hydrological cycle is

water, which has a distinguished characteristic of dissolving a wider range of

substances than any other liquid (Goldschieder and Drew, 2007). A number of

reactions occur between groundwater and soil as it flows through it until a chemical

equilibrium is maintained between water and surrounding material (Freeze and

Cherry, 1979; Hiscock, 1993). The chemistry of groundwater is an index of its

complex history, providing important clues to geological environment, indication of

groundwater recharge, discharge, movement and storage (Afsin, 1997).

Groundwater is one of the earth’s widely distributed, renewable and most

important resources. It is generally considered least polluted compared to other inland

water resources, but studies indicate that groundwater is not absolutely free from

pollution though it is likely to be free from suspended solids. The major problem with

the groundwater is that once contaminated, it is difficult to restore its quality. Hence

there is a need and concern for the protection and management of groundwater

quality. It is well known that no straight forward reasons can be advanced for the

deterioration of water quality, as it is dependent on several water quality parameters.

There exists strong correlations among different parameters and a combined effect of

their inter-relatedness indicates the water quality (Jothivenkatachalam et al. 2010).

6.2 ALTERATIONS IN CHEMISTRY OF GROUNDWATER

Groundwater derives its mineral character essentially from reactions between

rain water and the host rock over a time scale of days, months or years during

percolation. The extent of this water-rock interaction is controlled by the residence

103

time of the water and the mineralogy of the aquifer matrix. Alteration of water

chemistry in groundwater can occur through physical, chemical and biological

processes. Anthropogenic activities through excessive use of agrochemicals, release

of septic tank effluents and domestic wastes also have considerable effect on

groundwater quality (Fianko et al. 2010).

Geochemically, the most important acid produced in the soil zone is carbonic-

acid (H2CO3), derived from the reaction of carbon dioxide and rainwater

CO2 + H2O = H2CO3

The CO2 is also produced by the decay of organic matter and by the respiration

of plant roots. The weakly acidic H2CO3 solution attack rock-forming minerals

through a variety of reactions. Such reactions can be grouped into two principal types.

(1) Congruent dissolution of carbonate minerals, e.g.

Calcite + CO2 + H2O = Ca2++ 2HCO3- and

(2) Incongruent weathering of silicates to clays, e.g.

Feldspar + CO2 + H2O = kaolinite + cations + SiO2 + HCO3-

For both reactions, weathering results in an accumulation of HCO3- in water.

However, there are important differences in the stoichiometry of the two types of

reactions. For weathering of carbonate minerals like calcite, dolomite and aragonite,

the HCO3- ion concentration is balanced by cations like Ca2+ and Mg2+ on an

equivalent basis. On the other hand, kaolinisation of silicate minerals results in SiO2

in solution which is related to the HCO3- concentration through the composition of the

primary silicate (Freeze and Cherry, 1979).

The source of dissolved major cations and anions in groundwater can be

reconstituted in terms of weathering of minerals present in geological formations.

Some weathering reactions of minerals such a calcite (CaCO3), dolomite

[CaMg(CO3)2] and gypsum (CaSO4) can be written as:

CaCO3 + H2CO3 → Ca2+ + 2HCO3─,

CaMg(CO3)2 + 2H2CO3→ Ca2+ + Mg2+ + 4HCO3─,

CaCO3 + H2SO4→ Ca2+ + 2SO42+ + H2CO3,

CaMg(CO3)2 + 2H2SO4→ Ca2+ + Mg2+ + 2SO42─ + 2H2CO3,

CaSO4→ Ca2+ +SO42─,

104

The above reactions clearly indicate that if the weathering is by carbonic-acid,

the Ca-HCO3 in waters derived form calcite weathering is 1:2, whereas for dolomite

weathering the equivalent ratio is 1:4. If weathering process is initiated by sulphuric-

acid, the CaSO4 ratio involved would be 1:1 for calcite and 1:2 for dolomite. The

relative proportions of the various ions in solution depend on their relative

abundances in the host rock and their solubility. Carbonate minerals are the main

source of Ca2+ ion in natural waters whereas Mg2+ ion is mainly derived from

dolomites (Garrels and Mackenzie, 1971; Holland, 1978; Tyagi et al. 2009).

Human activities commonly affect the distribution, quantity, and chemical

quality of water resources. The range in human activities that affect the interaction of

groundwater and surface water is broad. Agriculture has been the cause of significant

modification of landscapes throughout the world. Tillage of land changes the

infiltration and runoff characteristics of the land surface, which affects recharge to

groundwater, delivery of water and sediment to surface-water bodies, and

evapotranspiration. All of these processes either directly or indirectly affect the

interaction of groundwater and surface water.

Significant changes in water quality accompany the movement of water

through agricultural fields. The water lost to evapotranspiration is relatively pure;

therefore, the chemicals that are left behind precipitate as salts and accumulate in the

soil zone. These continue to increase as irrigation continues, resulting in the

dissolved-solids concentration in the irrigation return flows being significantly higher

in some areas than that in the original irrigation water. To prevent excessive buildup

of salts in the soil, irrigation water in excess of the needs of the crops is required to

dissolve and flush out the salts and transport them to the ground-water system. Where

these dissolved solids reach high concentrations, the artificial recharge from irrigation

return flow can result in degradation of the quality of groundwater and, ultimately, the

surface water into which the groundwater discharges (http://pubs.usgs.gov/circ/circ11

39/pdf/part2.pdf).

Above all, important sources which can cause discernible changes in the

chemistry of shallow groundwater are related to the indiscriminate disposal of wastes

generated from leather industries (both solid and liquid wastes). These tanneries can

contribute Na-Cl, SO4, HCO3 and some hazardous trace metals to the groundwater

105

system. Keeping this fact in consideration, 74 groundwater samples were collected

and analyzed for physio-chemical characterization.

6.3 PHSIO-CHEMICAL CHARACTERISTICS OF GROUNDWATER

The summary of physico-chemical parameters of water samples analyzed

including pH, electrical conductivity (EC), total dissolved solids (TDS), are given

below.

6.3.1 Hydrogen Ion Concentration (pH)

Values of pH were measured at well sites, which range between 6 to 7.6 and

6.8 to 8.5 during pre-monsoon 2010 and post-monsoon 2010, respectively (Table-3.1a

and 3.1b). The groundwater thus is mildly acidic to slightly alkaline in nature. As far

as human consumption is concerned, all the samples may be considered fit, as they are

neither acidic nor strongly alkaline.

6.3.2 Electrical Conductivity

Electrical conductivity is an important parameter in groundwater quality

assessments for drinking and irrigation, since it is related to the concentration of

charged particles in water. The presence of charged particles in the water increases its

conductivity.

In the study area, EC values ranges between 600-1600 µS/cm

during 2010. The EC values during November 2010 were reported in between 400-

1400 µS/cm. On the basis of Electrical conductance, groundwater is classified (Table-

6.1) as given by Sarma and Narayanaswamy (1981).

Table-6.1: Classification of groundwater samples on the basis of EC

ClassEC (µS/cm

at 25o C)Pre-monsoon

2010Post-monsoon

2010Low Conductivity < 500 0 11% (4 Samples)Medium Conductivity Class I

500- 1000 43% (16 Samples) 51% (19 Samples)

Medium Conductivity Class II

1000- 3000 57% (21 Samples) 38% (14 Samples)

High Conductivity Class III

> 3000 0 0

106

6.3.3 Total Dissolved Solids (TDS)

In natural waters, dissolved solids consists mainly of inorganic salts such as

carbonates, bicarbonates, chlorides, sulphates, phosphates and nitrates of calcium,

magnesium, sodium, potassium, iron etc. and small amount of organic matter and

dissolved gases. In the present study the values of total dissolved solids (TDS) in the

groundwater varies from 634 to 1480 mg/l during pre-monsoon season (June 2010).

Eighteen out of 37 samples have values of >1000 mg/l, the average value for the

samples being 1017 mg/l. The TDS values during November 2010 range between 716

to 2481 mg/l with an average value of 1461 mg/l, indicating high mineralization in the

study area in both the seasons. During post-monsoon season, 89% of groundwater

samples have TDS value of >1000 mg/l (Table-6.2). It may be concluded that there is

more mineralization of groundwater during post-monsoon season. Water containing

more than 500 mg/l of TDS is not considered desirable for drinking water supplies,

though more highly mineralized water is also used where better water is not available.

For this reason, 500 mg/l as the desirable limit and 2000 mg/l as the maximum

permissible limit has been suggested for drinking water. Water containing TDS more

than 500 mg/l causes gastrointestinal irritation (BIS, 1991).

Table-6.2: Classification of groundwater based on TDS

Category TDS (mg/l) Pre- monsoon 2010

Post- monsoon 2010

Fresh water 0- 1,000 51% (19 Samples) 11% (4 Samples)Brackish water 1,000- 10,000 49% (18 Samples) 89% (33 Samples)Saline water 10,000- 100,000 0 0Brine water > 100,000 0 0

The TDS distribution maps for the pre and post-monsoon seasons are shown in

Figure-6.1a and 6.1b. During June 2010, areas with TDS >1000 mg/l lie in North-east,

central and western parts in vicinity of Dolawa, Utmanpur, Sarmba, Kishanpur

Tadwa, Tikau Purwa, Kanikamau and Lalupur. This high TDS zone in the north of the

study area show coincidence of deepest water level conditions during the mentioned

period, which can be attributed to large scale pumping of the aquifer. The presence of

thick top clay layer in this high TDS zone can not be ruled-out which can account for

107

higher TDS values through deficient recharge and thus less dilution of the

groundwater.

5000 10000 15000 20000

050

0010

000

1500

020

000

2500

030

000

3500

040

000

4500

0

Sai R

iver

Easting in metres

Nor

thin

gin

met

res

Ga

nga

Rive

r

05Km

Scale < 700

700-800

800-900

900-10001000-11001100-12001200-13001300-1400> 1400

INDEX

Figure-6.1a: Distribution of TDS in the Study Area (Pre-monsoon 2010)

The distribution of TDS values in post-monsoon 2010 period (Figure-6.1b) is

markedly different from pre-monsoon 2010. During November 2010, about 89% of

the analyzed samples are brackish. In general, entire area is characterized by TDS of

>1000 mg/l except few parts in north-west and south of the study area. This drastic

increase in the TDS values in the entire area can be attributed to the release of salts

from agricultural fields after rainfall and to the irrigation return flow as agriculture is

108

the prominent activity in the entire area. Areas with very high TDS values above 2200

mg/l lie in the vicinity of Sai river in the north of the study area.

5000 10000 15000 20000

05

000

100

00

150

002

000

02

500

030

000

35

000

400

004

500

0

Sai R

iver

Easting in metres

No

rth

ing

inm

etre

s

Ga

nga

River

0 5Km

Scale < 10001000-13001300-16001600-19001900-22002200-25002500-2800> 2800

INDEX

1900

2200 2500

2800

Figure-6.1b: Distribution of TDS in the Study Area (Post-monsoon 2010)

6.3.4 Hardness

During June 2010, the hardness in the study area varies from 112 – 410 mg/l

with an average value of 202 mg/l. Values above desirable limit (> 300 mg/l) were

recorded at Riyamau, Sarmba, Nibigera and Bamhnan Salehnagar (Table-6.3). During

November 2010, hardness ranges between 100-635 mg/l with an average value of 280

mg/l. Samples 2, 3, 4, 5, 6, 13, 14, 16, 18, 19, 23, 25, 27, 31 and 34 show the value

109

above desirable limit, constituting about 41% of the total analyzed samples. Thus

groundwater during both the seasons, viz. June 2010 and November 2010 falls in the

realm of moderately hard to very hard. However, except samples 5 and 14 (shadipur

and Barithana) collected in November 2010, all the samples analyzed are indicated to

be with in the permissible limit of drinking water standard (BIS, 1991).

Table-6.3: Hardness classification of groundwater

Hardness of CaCO3

(mg/l)

Water Class Pre- monsoon 2010

Post- monsoon2010

0 – 75 Soft 0 075 – 150 Moderately hard 24% (9 Samples) 11% (4 Samples)150-300 Hard 65% (24 Samples) 49% (18 Samples)

> 300 Very hard 11% (4 Samples) 41% ( 15 Samples)

6.4 CLASSIFICATION OF GROUNDWATER

To see the changes in groundwater chemistry at different locations and zones

and the extent of water rock interaction, major ion data of water samples of both the

time periods were plotted on Piper Trilinear diagram shown in Figure-6.2a and 6.2b.

6.4.1 Piper’s Trilinear Diagram

Piper diagrams are broadly used in hydrogeology as they illustrate the

hydrochemical characteristics of groundwater by representing the percentage of

anions and cations in meq L─1 in separate triangular diagrams (Freeze and Cherry,

1979; Helena et al. 1998). Geochemically similar waters are clustered in clearly

defined areas, indicating water mixing phenomena, precipitation, dissolution, etc. All

groundwater samples collected from the study area have been plotted in a Piper

diagram (Figure-6.2a). Based on the interpretation of the Piper diagram of pre-

monsoon 2010, the following hydrochemical considerations can be pointed out:

So far as the relative abundance of cations are concerned, 62% are alkalis,

32% exhibit no dominant signature and the rest 6% are magnesium type.

Among anionic species, 49% fall in no dominant field, 27% are bicarbonate

type and the remaining 24% samples are chloride type.

110

Figure-6.2a: Chemical facies identified on Piper’s Diagram in groundwater samples collected in June 2010

In post-monsoon samples (Figure-6.2b), the observed trend on Piper’s Diagram in

terms of relative abundance of cationic and anionic species is as follows:

Alkalis represent the most dominant group, comprising 86% of the samples

and the remaining 14% of the samples do not exhibit any dominant cationic

signature.

111

Among anions, 54% of the samples do not have any dominant anionic

signature, followed by 38% with relative abundance of bicarbonates and the

remaining 8% of samples exhibit chloride type.

Figure-6.2b: Chemical facies identified on Piper’s Diagram in groundwater samples collected in November 2010

The majority of the samples, therefore, are “alkali-bicarbonate” and “alkali

bicarbonate-chloride type” with Na having an overwhelming abundance over K. The

remaining samples exhibit mixed character with composition varying from mixed

alkali bicarbonate to alkali bicarbonate calcium chloride type.

112

6.4.2 L-L Diagram

To evaluate the chemical evolution of groundwater in the study area, the major

ion chemistry of both pre-monsoon and post-monsoon period has been summarized in

the form of the Langelier and Ludwig (1942) L-L diagram shown in Figure-6.3a and

6.3b. None of the samples qualify to be called a typical Ca-Mg-HCO3 type of local

meteoric water (LMW), except sample no. 33 collected from kanikamau during post-

monsoon 2010. Pre-monsoon 2010 plot (Figure-6.3a) helps in identifying five

different chemical types of groundwater.

Group I, comprising (32%) 11 samples occupies the central part of the plot

and thus exhibit mixed chemical characteristics. In this group, groundwater samples

are dominated by Na++ K+ and HCO3, averaging to 17 and 41% of the total ionic

concentration (TDS), while as Cl─ + SO42─ constitutes about 29% of the total ionic

concentration (Table-6.4). This group may, therefore, be designated as “Mixed alkali-

bicarbonate type”.

Group II groundwater samples (32%) have higher concentration of Cl─ +

SO42─ and HCO3─, in which the former ions constitute the average of 37% and the

later constitute 32% of the total ion chemistry. The HCO3─ and Cl─ differentiate the

fresh and contaminated water environments respectively. Moreover, in group II, 58%

of the samples show hardness > 1000 mg/l and this group is named as “Chloride-

sulphate-bicarbonate type”.

Group III (14%) samples provides a clue to possible local meteoric water

(LMW) as Ca + Mg-HCO3 in this group constitute about 55% of the total ionic

chemistry. Moreover, very high Na, K and SO4 contents in the samples of this group

and due to the fact that these concentrations are more or less in the proportion

required for the formation of the salts like Na2SO4 and K2SO4 indicates that these

samples have been chemically evolved due to precipitation and dissolution of such

salts. This group is designated as “Ca-Mg-HCO3-SO4 type”.

Group IV (16%) samples are dominated by Cl─ + SO42─ and HCO3─ ionic

concentrations comprising about 29 and 39% respectively. Samples in this group are

thus classified as “Mixed bicarbonate type”.

Group V (6%) samples are characterized by higher concentrations of Cl─ +

SO42─ which constitute about 49% of the total ion chemistry. Samples of this group

113

viz; samples 22 and 34 plot to the extreme right top corner of the diagram and this

group can be designated as “Cl─ + SO42─ mixed type”.

At the first glance the post-monsoon (Figure-6.3b) scenario looks very similar

to that of pre-monsoon. A closer look however, reveals that groups I, II and III have

clustered more towards the centre from which we infer that groundwater in these

groups have evolved with the passage of time. The samples of group V (22 and 34) of

pre-monsoon season seem to have been incorporated into groups II and I of the post-

monsoon season. Group V of post-monsoon containing sample no. 33 collected from

Kanikamau plots in Ca-Mg-HCO3 (LMW) field.

Figure-6.3a: Langelier and Ludwig (L-L) diagram of June 2010 samples

Table-6.4: Relative abundance of cations and anions in chemical groups ofgroundwater system in the study area (June 2010)

Group Cations Anions

I Na + K > Ca + Mg HCO3 > Cl + SO4

II Na + K > Ca + Mg Cl + SO4 > HCO3

III Na + K ≈ Ca + Mg HCO3 > Cl + SO4

IV Na + K > Ca + Mg HCO3 > Cl + SO4

V Na + K >> Ca + Mg Cl + SO4 > HCO3

114

Figure-6.3b: Langelier and Ludwig (L-L) diagram of November 2010 samples

From above discussion, it can be concluded that chemical characteristics of the

groundwater in the study area has evolved through a series of events and primordial

chemical characteristics of the meteoric water has been completely obliterated. Most

of the groups seem to have acquired their major ion chemistry as a result of various

processes which may be attributed to the combined action of geogenic and

anthropogenic activities.

6.5 SUITABILITY OF GROUNDWATER FOR HUMAN UTILISATION

The main aim of water analysis is to evaluate the suitability of water for

various uses; like domestic, irrigation and industry. In the last few decades, there has

been a tremendous increase in the demand for fresh water due to rapid growth of

population and the accelerated pace of industrialization. Rapid urbanization,

especially in developing countries like India, has affected the availability and quality

of groundwater due to its over-exploitation and indiscriminate waste disposal,

especially in urban areas. According to World Health Organization (WHO), about

80% of all diseases in human beings are water borne in one way or other way. Once

115

the groundwater is contaminated, its quality can not be restored by stopping the

pollutants from the source. It, therefore, becomes imperative to regularly monitor the

quality of groundwater and to suggest ways and means to protect it (Ramakrishnaiah

et al. 2009).

The World Health Organisation (1984), Indian standard drinking water

specification (BIS, 1991) and Indian Council of Medical Research (ICMR) have given

drinking water standards, which, in general provide safeguard to the human health.

6.5.1 Drinking Water Quality Assessment (Major Elements)

All the groundwater samples from the study area show TDS values above the

desirable limit of 500 mg/l in both the seasons. Post-monsoon TDS values are higher

than those of the pre-monsoon season with four samples, sample 2, 3, 12 and 29,

showing TDS values above the maximum permissible limit of 2000 mg/l (BIS, 1991).

The SO4- concentration of four samples in June 2010 cross the desirable limit

of 200 mg/l, while during November 2010, 57% of the samples show SO4-

concentration > 200 mg/l, including 2 samples, 12 and 32 with concentration more

than the maximum permissible limit of 400 mg/l (BIS, 1991). The SO4- concentration

is more in post-monsoon samples with 12 samples having SO4- value exceeding 300

mg/l. The high intake of SO4- may result in gastrointestinal irritation and respiratory

problems to the human system (Maiti, 1982; Subba Rao, 1993; Subramani et al.

2005).

The NO3─ concentration in groundwater during post-monsoon 2010 lies well

below the desirable limit of 45 mg/l (BIS, 1991), except samples 18 and 25, both of

which lie interestingly in the main agricultural centers of the study area. A different

trend of NO3─ distribution is observed during pre-monsoon 2010 with 10 samples

having NO3─ concentration above desirable limit of 45 mg/l (BIS, 1991). However,

NO3─ recorded in all the samples in both the time periods lie with in the permissible

limit (BIS, 1991).

During June 2010, six samples cross the desirable limit of Cl─ in groundwater,

where as during November 2010, 12 among 37 samples cross the desirable limit (BIS,

1991). The Cl─ concentration above desirable limit in most of the samples can be

attributed to the agricultural activities, especially those lying on north-west of the

116

study area in the adjoining areas of Pariar, where possibilities of leaching from

fertilizers can not be ruled out. The adulteration of fertilizers by common salt in the

agricultural practices could be the main contributor of Na and Cl into the groundwater

system.

WHO or BIS has not given any desirable or permissible limit for Na, but as

per the studies carried out by USA Environmental Protection Agency and Minnesota

Pollution Control Agency for the period from 1999-2008 (www.wikipedia.com),

clearly indicates that high sodium values in drinking water are not advisable due to

known role of this element in hypertension, heart diseases and kidney related

problems. Environment Protection Agency of USA, as a matter of fact, recommends a

value of 20 mg/l of Na in the ideal drinking water based on the routine requirement of

Na by human body and availability of Na through other solid intakes (Alam, 2010).

The Canadian drinking water quality objective for Na is an Aesthetic Objective (AO)

of 200 mg/l. The water with a Na value of more than this is not categorized as

drinking water meant for continuous consumption.

In June 2010, six samples out of 37 samples have Na more than 200 mg/l,

where as 21 samples (57%), cross the limit of 200 mg/l in post-monsoon with highest

Na value recorded at 428 and 522 mg/l in sample 12 and 29, respectively.

So far as K is concerned, 5 samples during November 2010 show values of >

100 mg/l. During pre-monsoon 2010, only 3 samples cross 100 mg/l limit and the rest

lie below 100 mg/l. Vital functions of K includes its role in nerve stimulus, muscle

contractions, blood pressure regulation and protein dissolution. Its excess in drinking

water however is not a cause of any major worry as human renal system has ability to

compensate its fluctuating levels with in the human body (http://www.lenntech.com/p

eriodic/water/potassium/potassium-and-water.htm).

K values above 100 mg/l in both the time periods point to the utilization of

potash fertilizers in the study area. The utilization of potash fertilizers in Unaao

district has drastically increased from 45955 metric tones in 2008 to 71887 metric

tones in 2009-10, respectively. The area under investigation has consumed 26944

metric tones (38%) in year 2009-10 (http://updes.up.nic.in/spatrika/engspatrika/select

_distt_yr.asp).

117

Calcium in groundwater generally is not discussed from the perspective of

human health, but keeping the present situation in consideration, it is imperative to

throw some light on it. Calcium values measured in the two sets of samples (June

2010 and November 2010) give average value of 59 and 72 mg/l, respectively. Only 6

out of 37 samples have calcium value more than the prescribed lower limit during

June 2010 (BIS, 1991), where as during November 2010, 16 samples have calcium

value above the lowest desirable limit. Earlier work carried out in the area also shows

that shallow groundwater is deficient in calcium almost everywhere in the study area.

Deficiency of calcium is responsible for rickets and defective teeth and other diseases

like osteoporosis (Faruqi, 2002).

The presence of Mg in groundwater is beneficial for cardiovascular and

nervous system of human beings. Mg ions in presence of sulphate ions act as laxatives

(CGWB, 2002). In both sets of samples, only sample 2 and 33 collected during

November 2010 cross the maximum permissible limit (BIS, 1991). The average Mg

concentration in both sets of samples is relatively consistent at 43 and 41 mg/l. 12

samples in June 2010 and 14 in November 2010 (35%), however, have Mg

concentrations below the lowest desired value of 30 mg/l (Table-6.5). As per several

epidemiological studies, deficiency of Mg may result in heart problems and one of its

compound, magnesium-chloride can cause diarrhea, which enters the groundwater in

the form of herbicides and insecticides (http://grande.nal.usda.gov/ibids/index.php?m

ode2=detail).

Fluorosis, which is in deed the matter of speculation that calls for research in

the study area, has been discussed in Chapter-9, however it is important to discuss it

in this section dealing with the quality of groundwater for drinking purposes. The

effects of fluoride on human health have been extensively studied (WHO, 1970;

1984). Fluoride is an indispensable element for the maintenance of dental health.

Fluoride concentrations up to 1.5 mg/l are beneficial for reducing cavities in children

during the calcification period (Srinivasa, 1997). Fluoride concentrations above 1.5

mg/l may lead to dental mottling (fluorosis), characterized initially by opaque white

patches on teeth. In advanced stages of dental fluorosis, teeth display brown to black

staining, followed by pitting of teeth surfaces during the tooth calcification stage from

fetal to 12 years of age (Apambire et al. 1997). If the fluoritic water is consumed for a

118

longer period, then skeletal fluorosis also develops but it shows its symptoms in the

young age adults around age group of 30 to 35 years (Faruqi, 2002).

The fluoride concentration in present study shows an increase towards post-

monsoon season, rising from average value of 0.93 in June 2010 to 1.11 mg/l in

November 2010, respectively. Overall, 38% of samples in both time periods (June

2010 and November 2010) show objectionable fluoride concentrations i.e., above the

maximum permissible limit of 1.5 mg/l (BIS, 1991).

Taking the instructions of Indian Standard Specifications for Drinking Water

(IS: 10500) in to consideration, 34 out of 74 samples analyzed from the area over

consecutive pre and post-monsoon periods of 2010 should be rejected for drinking

purposes as F content is < 0.60 mg/l (http:/hppcb.gov.in). This deficiency may cause

increased dental caries and possibly osteoporosis due to the lack of fluoride in the diet

(www.wikipedia.com). According to many documents from UNICEF and WHO, such

an area warrants fluoridization for drinking purposes through adding recommended

fluoride salts.

6.5.2 Drinking Water Quality and Trace Elements

Trace element concentrations were evaluated for 23 groundwater samples

collected in June 2010. Table-6.5 summarizes the prescribed limits of various trace

metals and their observed concentration ranges in the study area. Salient observations

are given below:

The concentration of Pb in three samples (sample 5, 12 and 14) are higher than

the permissible limit as per BIS (1991). Neurological problems, especially in

children are the principal concern for chronic Pb exposures (Goyer and

Clarkson, 2001).

5 among 23 samples (sample 5, 12, 14 and 23) have Cd concentration above

permissible limit. Interestingly, these high Cd values are associated with high

Pb values. Pb is very prone to accumulation in surface horizons of soil because

of its less mobility. However Cd tends to be more mobile in soil systems and

therefore more available to plants than many other heavy metals (Alloway,

1995). Chronic Cd exposures results in kidney damage, bone deformities, and

cardiovascular problems (Goyer and Clarkson, 2001).

119

In two samples (4 and 21) Zn exceeds the desirable limit. Zn is an essential

requirement for good health, excess Zn can be harmful by damaging the nerve

receptors in the nose, which can cause anosmia (www.wikipedia.com).

Excessive absorption of Zn also suppresses Cu and Fe absorption in human

beings.

One sample (sample 5) contains Mn above the desirable limit of 0.05 mg/l

(BIS, 1991). So far as Mn is concerned, no adverse symptoms are reported on

human health when water enriched with this element is consumed over a long

period of time.

120

Table-6.5: Range of concentration of various major and Trace elements in groundwater Samples and their comparison with W.H.O. (1994) and B.I.S. (1991) Drinking Water Standards.

(BIS 1991) W.H.O. (1993) Conc. In the study area (mg/l)

Constituents

Highest desirable

level

Max. permissible

level

Highest desirable

level

Max. desirable

level June 2010 November 2010pH 6.5-8.5 6.5-9.5 7-8.5 6.5-9.2 6.0-7.7 6.8-8.5

Total Hardness 300 600 100 500 112-410 100-635TDS 500 2000 634-1480 716-2481

Calcium 75 200 75 200 21-131 32-145Magnesium 30 100 3-98 8-132

Sodium 82-345 68-522Chloride 250 1000 200 600 85-644 43-455Sulphate 200 400 45-320 41-555Fluoride 0.6-1.2 1.5 0.16-4.68 0.24-4.92Nitrate 45 100 2-91 1-84Copper 0.05 1.5 0.05 15 0.0007-0.0033 -

Iron 0.3 1 0.1 1 0.0351-0.1322 -Lead 0.1 0.1 0.0008-0.1949 -

Manganese 0.1 0.5 0.05 0.5 0.0074-0.1396 -Cadmium 0.01 0.01 0.01 0.0001-0.0196 -

Nickel 0.1 0.3 0.0004-0.0013 -Cobalt 0.0000-0.0002 -

Chromium 0.05 0.05 0.0033-0.0275 -Zinc 0.1 15 5 15 0.0098-0.1676 -

Selenium 0.01 0.1 0.0000-0.0007 -Boron 0.0173-0.0650 -

Almunium 0.03 0.2 0.0119-0.1634 -Arsenic 0.05 0.0002-0.0069 -Silver 0.0000-0.00004 -

121

15 among 23 samples cross the desirable limit of Al (BIS, 1991). Large

aluminum intake may negatively influence health. Particularly people with

kidney damage are susceptible to aluminum toxicity. Aluminum is probably

mutagenic and carcinogenic. Increased aluminum intake may also cause

osteomalacia (vitamin D and calcium deficits) (http://www.lenntech.com/perio

dic/water/aluminium/aluminum-and-water.htm). A noteworthy source of Al in

study area could be aluminum sulphate, which is frequently used as basic

material in leather tanneries.

6.6 SUITABILITY OF WATER FOR IRRIGATION PURPOSES

Groundwater in the study area finds intensive use in irrigation. In Unnao

district, of which study area is a part, agriculture is very important income source,

comprising about 66% of the whole district. About 88% of the net cultivated area in

Unnao district is falling under irrigated category, of which 69% irrigation is being

done by groundwater (CGWB, 2002).

The suitability of groundwater for agricultural purposes depends on the effect

of mineral constituents of water on both plants and soil. Effects of salts on soils

causing changes in soil structure, permeability and aeration indirectly affect plant

growth. Wilcox (1955) and US Salinity Laboratory Staff (1954) proposed irrigational

specifications for evaluating the suitability of water for irrigation use. There is a

significant relationship between sodium adsorption ratio (SAR) values for irrigation

water and the extent to which sodium is adsorbed by the soils. If water used for

irrigation is high in sodium and low in calcium, the cation exchange complex may

become saturated with sodium, which can destroy the soil structure owing to

dispersion of clay particles (Singh, 2002; Tyagi et al. 2009).

The electrical conductivity is a measure of salinity hazard to crop as it reflects

the TDS in the groundwater. Parameters such as sodium absorption ratio (SAR) and

residual sodium carbonate (RSC) were estimated to assess the suitability of

groundwater for irrigation. The salt present in the water, besides affecting the growth

of plants directly also affects soil structure permeability and aeration, which indirectly

affect plant growth (Mohan et al. 2000; Umar et al. 2001).

122

6.6.1 Sodium Adsorption Ratio (SAR) Criterion

Sodium absorption ratio is the measurement of sodium content relative to

calcium and magnesium in soil-water medium which influences soil properties and

plant growth. The total soluble salt content of irrigation water generally is measured

either by determining its electrical conductivity (EC), reported as micromhos per

centimeter, or by determining the actual salt content in parts per million (ppm).

Normally, irrigation water with an EC of < 700 μmhos cm-1 causes little or no threat

to most crops while EC > 3000 μmhos cm-1 may limit their growth (Tijani, 1994;

Khodapanah et al. 2009).

The sodium or alkali hazard in the use of water for irrigation is determined by

the absolute and relative concentration of cations and is expressed as the sodium

adsorption ratio (SAR).The following formula is used to calculate SAR:

SAR =

2

MgCa

Na

Ions in the equation are expressed in milliequivalent per liter (meq/l).

There is a significant relationship between SAR values of irrigation water and

the extent to which sodium is absorbed by the soils. Continued use of water with a

high SAR value leads to a breakdown in the physical structure of the soil caused by

excessive amounts of colloidally absorbed sodium. This breakdown results in the

dispersion of soil clay that causes the soil to become hard and compact when dry and

increasingly impervious to water penetration due to dispersion and swelling when

wet. Fine-textured soils, those high in clay, are especially more vulnerable to this

action.

The calculated value of SAR in the study area ranges from 1.75-10.46 with an

average of 4.02 during pre-monsoon 2010, where as in post-monsoon 2010; it varies

from 1.59 to 11.64 with an average of 5.71 in groundwaters (Table-6.6 and 6.9). SAR

of all the samples lie below 10, except sample 22 collected during June 2010 from

Barikhera and sample 29 collected during November 2010 from Kishanpur Tadwa. So

far as former sample is concerned, water from this dug-well is not used for irrigation

purposes at all as it is located far away from the agricultural fields, where as in later

123

case, it is quite possible that this dug-well is temporarily used for irrigation purposes

as it lies in the vicinity of a vegetation yard observed during field survey. The SAR

values of June 2010 when plotted on the US salinity diagram (Richards, 1954), show

that 76% samples fall in C3-S1 and 16% in C2-S1 respectively (Figure-6.4a). Samples

falling in C3-S1 are not advisable to the soils with scarce drainage and the

prerequisite for samples falling in C2-S1 to be used for irrigation is that the soil must

encompass through moderate leaching. 2 samples fall in C3-S2 and 1 with SAR > 10

in C2-S2, the rest of the samples fall in good to excellent class from the point of view

of irrigation.

Figure-6.4a: SAR versus E.C. (June 2010)

During November 2010, 9 samples (24%) fall in C3-S2 (high salinity and

moderate sodium water) and 1 sample fall in C2-S2 (moderate salinity and moderate

sodium water) (Figure-6.4b). Therefore 10 samples exhibit medium sodium hazard.

Such water can show adverse effect in fine textured soils where frequent cation

124

exchange occurs, application of gypsum in agricultural fields can overcome this

problem. When the options are limited, these waters can be used in coarse-grained

soils where sizable pore-spaces does not allow cation exchange to take place

(Karanth, 1987). The remaining samples fall in C2-S1 (35%) and C3-S1 (38%) for

which the necessary requisites have already been discussed. The quality classification

of groundwater is given below in Table-6.6 (USSL, 1954).

Table-6.6: Quality Classification of Irrigation Water (after USSL, 1954)

Water Salinity Hazard E.C (Micromhos/cm at 250 C)

SAR Value

Excellent <250 <10

Good 250-750 10-18

Fair 750- 2250 18-26

Poor >2250 >26

Figure-6.4b: SAR versus E.C. (November 2010)

125

6.6.2 Residual Sodium Carbonate (RSC) Parameter

Calcium and magnesium has a tendency to precipitate as carbonate, when

there is high percentage of bicarbonate in the groundwater. To quantify this effect, an

experimental parameter termed as Residual Sodium Carbonate can be used. The

concept of residual sodium carbonate (RSC) is employed for evaluating high

carbonate waters and is calculated by the formula given below:

RSC = (CO32─ + HCO3

─) ─ (Ca2+ + Mg2+)

Where, the concentrations are reported in meq/l.

RSC gives an account of calcium and magnesium in the water sample as

compared to carbonate and bicarbonate ions. RSC value less than 1.25 indicates low

hazard, whereas a value of 1.25- 2.5 indicates medium hazard and more than 2.5

indicates high hazard to crop growth (Kaur and Singh, 2011). The classification of

irrigation water according to the RSC value is presented in Table-6.7.

Table-6.7: Quality of Groundwater Based on Residual Sodium Carbonate (RSC)

RSC (meq/l) Quality

Pre-Monsoon 2010 Post-Monsoon 2010

Representative Samples

RepresentativeSamples

<1.25 Good 29 13

1.25-2.5 Doubtful 3 6

>2.5 Unsuitable 5 18

The value of residual sodium carbonate (RSC) have been calculated for both

the seasons (Table-6.9) and compared with the above classification. It was found that

during pre-monsoon 2010, 8 (22%) samples, where as during November 2010, 24

(85%) of the samples fall in doubtful to unsuitable quality. The remaining samples are

of good quality from irrigation point of view. An important note-worthy point here is

that when RSC is > 2.5, a salt layer called ‘Reh’ gets formed. A close study of the

analytical data of water samples in both the seasons indicate that water showing high

RSC values are associated with high fluoride concentration at most of the places.

126

6.6.3 Sodium Percentage (Na%)

When the concentration of sodium ion is high in irrigation water, Na+ tends to

be absorbed by clay particles, displacing magnesium and calcium ions. This exchange

process of sodium in water for Ca+2 and Mg+2 in soils reduces the permeability and

eventually results in soil with poor internal drainage (Kaur and Singh, 2011). Doneen

(1966) method was used to calculate the sodium percentage. The sodium percentage

is calculated by the following equation:

Na% = [(Na+ + K+)/(Ca2+ + Mg2+ + Na+ + K+)]* 100

Here, all the concentrations are expressed in milliequivalents per litre (meq/l).

During June 2010, Na% in the study area varies from 16 to 58% with an

average of 32%. In this session, it was observed that 81% of the water samples fall

under excellent to good category and the remaining 19% fall under permissible

category (Table-6.8). In November 2010, Na% range from 37 to 78% with an average

of 62%. In this period, about 62% (23) samples have high Na% (above 60%) and one

sample bearing number 20 records Na% just above 78%, such waters are not suitable

for irrigation purposes. High percentage of Na+ with respect to (Ca2+Mg2+Na+) in

irrigation water, causes deflocculating and impairing of soil permeability (Singh et al.

2008).The rest of the samples (38%) fall under good to permissible category water

(Table-6.8).

Table-6.8: Classification of groundwater based on sodium percentage

Na% Quality

Pre- Monsoon 2010 Post- Monsoon 2010

Representative Samples

RepresentativeSamples

< 20 Excellent 3 (8%) 0

20-40 Good 27 (73%) 3 (8%)

40-60 Permissible 7 (19%) 11 (30%)

60-80 Doubtful 0 23 (62%)

>80 Unsuitable 0 0

Analytical data were plotted on the Wilcox diagram (1955) relating EC and

sodium percent. The sodium percentage (Na%) in the area ranges up to 78%. In June

2010, 97% of the samples fall in category of ‘excellent to good’ and ‘good to

127

permissible’ quality and can be used for irrigation purposes (Figure-6.5a). Only one

sample plots in ‘permissible to doubtful’ category in this season. However, the trend

observed during November 2010 is a matter of concern as 62% of the samples fall in

‘permissible to doubtful’ category. The rest of the samples (38%) fall in ‘excellent to

good’ and ‘good to permissible category’ (Figure-6.5b).

Figure-6.5a: Plot of Sodium Percentage and Electrical Conductivity (based on Wilcox, 1955) of June 2010 for Classification of Groundwater for Irrigation

Uses.

128

Figure-6.5b: Plot of Sodium Percentage and Electrical Conductivity (based on Wilcox, 1955) of November 2010 for Classification of Groundwater for Irrigation

Uses.

6.7 SURFACE WATER QUALITY AND INTERACTION WITH

GROUNDWATER

Six samples were collected from Sai and Ganga river to evaluate their quality

and any possible relationship with the groundwater regime (Table-3.3a and 3.3b). The

analytical results of these samples when plotted in L-L diagram mostly occupy the

central part and thus exhibit a ‘mixed character’ (Figure-6.6). All samples plot outside

the meteoric or Ca-Mg-HCO3 type. Only sample S1, collected from Sai river during

June 2010, plots on the outer boundary of meteoric water field. Pre-monsoon samples

show more pronounced obliteration in their chemical characteristics than post-

monsoon samples.

129

Table-6.9: Groundwater parameters for irrigation purposes

June 2010 November 2010S/NO. LOCATION SAR RSC Na% SAR RSC Na%

1 Jagdeshpur 3.15 0.72 15.94 5.53 0.97 70.882 Fakirakhera 5.10 2.97 52.38 6.8 3.55 61.283 Argurpur 4.36 -0.14 50.04 4.41 8.9 52.324 Prithviramkhera 2.20 -1.45 20.44 3.63 0.53 57.35 Shadipur 3.44 -2.73 39.02 6.84 3.68 63.726 Dolawa 1.76 -3.04 23.06 6.25 2.6 69.917 Kursat 5.64 -1.23 30.31 6.18 4.88 68.508 Raghunathkhera 3.94 0.25 26.97 3.85 -3.49 54.839 Utmanpur 3.82 -3.94 29.46 1.59 -1.12 37.0310 Fatehpur Chaurasi 1.97 -0.63 31.69 8.09 5 72.711 Safipur 4.34 1.45 25.48 4.06 2.17 58.6312 Mawai Brahmnan 3.37 -5.56 37.17 9.85 5.22 74.1213 Riyamau 2.72 -4.92 28.23 5.71 4.68 64.5414 Barithana 4.99 1.43 25.76 5.99 8.1 69.1115 Munda 2.79 0.34 27.88 7.88 4.01 75.1916 K.ulha ataura 3.25 -2.69 20.47 4.48 0.5 62.0517 Jamlapur 3.67 -0.86 30.07 8.35 5.8 73.1218 Sarmba 2.97 2.28 22.48 4.53 2.55 61.3519 Rasulabad 5.45 0.92 25.32 6.67 1.78 75.4520 Mirzpur 1.75 -3.49 19.37 8.49 2.53 78.4121 Hansakhera 3.75 2.71 33.68 4.12 1.62 52.9722 Barikhera 10.46 0.20 25.72 6.88 1.83 71.8623 Mahipatkhera 6.62 3.89 32.14 6.95 1.31 66.78

130

24 Muminpur 3.61 -2.40 38.10 5.59 1.84 58.7925 Pariar 3.90 -0.84 41.65 7.3 -2.16 63.8726 Dostinagar 3.70 -1.16 31.36 6.41 5.66 65.1527 Nibigera 2.08 -1.07 29.77 8.32 8.32 72.3928 Bamhnan Salehnagar 3.82 1.49 25.11 4.07 1.84 57.1429 Kishanpur Tadwa 5.44 1.05 43.35 11.64 6.88 77.3330 Tikau Purwa 4.94 -2.01 27.87 6.77 0.8 68.5331 Chetankhera 2.96 1.29 39.11 2.23 -1.4 39.0732 S.Sarrai 2.26 -2.94 46.52 3.35 -1.37 45.3633 Kanikamau 5.32 -0.18 57.56 2.71 -0.16 38.1334 Lalupur 8.52 -3.01 17.92 3.29 -0.13 57.0935 Lingrapurwa 4.33 2.21 44.29 2.67 -0.94 44.7236 Basdhana 3.73 0.07 27.67 3.97 1.77 57.7937 Dewara kalla 2.66 0.66 25.58 5.84 -0.03 65.76

131

The surface water samples are comparatively dilute with average TDS values

of 830 and 863 mg/l during June 2010 and November 2010. From Figure-6.1a and

6.1b, it is clear that groundwater TDS values tend to be moderate along Sai and

Ganga except during November 2010 when TDS values along Ganga lie in the range

of 1300 to 1600 in the upper half and 1600 to 1900 mg/l in the lower half of the river.

The moderate TDS values along these rivers provide evidence of effluent nature of

rivers.

During June 2010, surface water samples are dominated by bicarbonates

among anions and alkalis among cations where as in November 2010, majority of the

samples do not exhibit a preferred dominance of any ion which indicates that water

has undergone a significant hydrogeochemical evolution in this session. Sulphate

values are higher in November 2010 (11-272 mg/l) than in June 2010 (24-137 mg/l).

From irrigation point of view, 58% of samples are moderately saline with low

sodium values and can be used for agricultural purposes without any harm to the

crops. The remaining 42% samples show high values, > 1000 µS/cm and thus require

some proper treatment. RSC of all surface water samples lie well below 1.25 and thus

fall under ‘good category’.

Figure-6.6: Langelier and Ludwig (L-L) diagram for June and November 2010 of river water samples

132

6.8 SUMMARY

The groundwater sources in the study area have been evaluated for their

chemical composition and suitability for different uses. Various observations based on

this part of the study are:

The investigation indicates that TDS values are strikingly high in both the

seasons, averaging > 1000 mg/l. During pre-monsoon 2010, high TDS values

are mostly confined to central, western and some parts adjacent to Sai river in

the North-east of the study area.

From TDS distribution plot of November 2010, it can be logically inferred that

rock-water interaction can not be the lone process responsible for acquisition

of solutes and additional role of anthropogenic activities is evident,

particularly when TDS values reach up to 2300 mg/l.

This drastic increase in TDS values during November 2010 can be attributed

to the release of salts from agricultural fields and to less significant dilution

activity due to gentle gradient of the entire area, averaging 0.13 m/km.

From Piper’s Trilinear Plot, it is clear that alkalis are most dominant among

cations and bicarbonates among anions. A sizable number of samples exhibit

no dominant character which clearly indicates that water in the area has

undergone a series of chemical alterations.

On the basis of L-L diagram, ‘mixed alkali-bicarbonate, ‘Chloride-sulphate-

bicarbonate’, ‘Ca-Mg-HCO3-SO4’, ‘mixed bicarbonate’, and ‘Cl─ + SO42─

mixed’ chemical types of groundwater have been identified. Overall,

groundwater in both the time periods shows a mixed character which is the

outcome of various natural and anthropogenic processes.

An attempt made to evaluate the suitability of groundwater for drinking

purposes reveals that many parameters exceed the desirable and permissible

limits. The level of TDS, one of the deciding parameter of drinking water, is

higher than 500 mg/l in both time periods with sample 2, 3, 12 and 29 in post-

monsoon exceeding the maximum permissible limit of 2000 mg/l (BIS, 1991).

Sulphate concentrations are also higher, especially during November 2010, in

which values above 200 mg/l in 57% samples have been recorded including

two samples crossing the permissible limit of 400 mg/l.

133

High Na values in drinking water are not advisable due to the known role of

this element in hypertension, heart diseases and kidney related problems. In

aggregate, 73% of samples record Na above 200 mg/l. Na is particularly

higher in post-monsoon during which it reaches up to 522 mg/l.

The chloride content in the samples lies between 85-644 mg/l in June 2010

and 45- 455 mg/l in November 2010. Chloride is normally the most dominant

anion in water. In the present study; the value of chloride content in 18

samples has been found to be high (above 250 mg/l), which can cause

corrosion and pitting of iron plates or pipes.

The entire area can be called as ‘calcium deficit’ as only 29% of the samples

exhibit Ca level above the lowest desirable limit in both sets of samples with

average values of Ca being 59 and 72 mg/l for June and November 2010. Ca

deficiency can cause rickets, osteoporosis and can harm teeth also. Poor

people are more vulnerable to Ca deficiency due to low intake of calcium

through their daily meals.

Fluoride and fluorosis in the study area was perhaps the most discussed issue

during the last decade. About 38% in both sets of samples show fluoride level

above permissible limit, which is in fact the main outcome of the present study

that needs to be studied in great deatail. Fluoride above 1.5 mg/l in

groundwater causes mottling of skeleton and harms the enamel of teeth.

Victims of fluorisis complain of a vague pain in the joints of hands, feet,

knees, neck and spine. They even face difficulty in walking due to stiffness in

joints and due to neurological defects in advanced cases.

For drinking water purposes, majority of the trace element concentrations in

groundwater samples lie in safe limits except few cases (Table-6.5). The

results exhibited that Pb in 3 samples and Cd in 4 samples were recorded

above permissible limits (BIS, 1991). Pb in excess of its permissible limits is

responsible for many neurological problems, where as Cd causes kidney and

cardiovascular problems. Zn in two samples and Mn in one sample also

exceed their desirable limits (BIS, 1991). Excessive intake of Zn can cause

anosmia and can suppress the absorption of other elements required to human

134

body. In 65% of the total analysed samples, Al records above its desirable

limit. Its high concentration is carcinogenic and can cause osteomalasia.

During June 2010, SAR values range from 1.75 to 10.46 with an average value

of 4.02. In this period all the samples fall in ‘good to excellent category’ from

irrigation point of view except three samples which fall in C3S2 and C2S2

catagories. During November 2010, SAR values range from 1.59 to 11.64 with

an average value of 5.71. In this period, 27% samples exhibit medium sodium

hazard and thus are not ideal for agricultural purposes particularly on fine

textured soils.

On the basis of RSC values, it was found that 22% in June 2010 and 85% in

November 2010 fall in ‘doubtful to unsuitable’ category of irrigation. Samples

with high RSC values were interestingly associated with high fluoride values.

During June 2010, Na % in the study area ranges from 16-58% with an

average of 32%. In this time period, 81% samples fall under ‘excellent to

good’ category and 19% under ‘permissible’ category. In November 2010,

Na% ranges from 37-78% with an average of 62%. 23 (62%) samples record

high Na% (> 60%), and are thus not suitable for irrigation purposes. From

Wilcox diagram, it is inferred that during June 2010, only one sample plots in

‘permissible to doubtful’ category and the remaining 97% fall in ‘excellent to

good’ and ‘good to permissible’ category. During November 2010, 62%

samples fall in ‘permissible to doubtful’ category.

Six surface water samples were analyzed to evaluate their chemistry and

interaction with the groundwater regime. It was found that TDS values tends

to be moderate along Sai and Ganga river, which provides a clear evidence

that these rivers are of effluent nature. Moreover, as per L-L diagram, pre-

monsoon surface water samples show more obliteration in their chemical

characteristics than post-monsoon samples.