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321
KEYWORDS
ISSN: 0974 - 0376
NSave Nature to Survive
: Special issue, Vol. III:
www.theecoscan.inAN INTERNATIONAL QUARTERLY JOURNAL OF ENVIRONMENTAL SCIENCES
Prof. P. C. Mishra Felicitation Volume
Paper presented in
National Seminar on Ecology, Environment &Development
25 - 27 January, 2013
organised by
Deptt. of Environmental Sciences,
Sambalpur University, Sambalpur
Guest Editors: S. K. Sahu, S. K. Pattanayak and M. R. Mahananda
Kumar Manoj et al.
Cluster analysis
Permeability index
Principal component analysis
Sodium absorption ratio
Water quality index
321 - 330; 2013
SPATIAL ASSESSMENT AND CHARACTERISATION OF THE
SUBARNAREKHA RIVER WATER THROUGH INDEX ANALYSES
APPROACHES AND CHEMOMETRICS
322
KUMAR MANOJ, BALWANT KUMAR AND PRATAP KUMAR PADHY*
Department of Environmental Studies, Institute of Science, Visva – Bharati
Santiniketan - 731235, Birbhum, West Bengal, INDIA
E-mail: [email protected]
INTRODUCTION
Water is one of the most vital natural resources central to the survival of the living
beings. Fresh water accounts for just 2.6% of the total water available on the
earth. Out of this only a small fraction is readily available in rivers, lakes and as
groundwater. Rivers have always been the cradles of civilisation because of their
fertile basin and abundant freshwater resources. River water is used for drinking,
washing, animal husbandry, industrial, agricultural and recreational purposes.
However, unchecked anthropogenic activities, especially in the developing
countries, are increasingly making river water a stressed and unsustainable naturalresource. Industrial effluents, agricultural runoff, mining discharges, domesticwastes and municipal sewage all contribute to the pollution of river waters. Forbetter management and sustainable development of river water resourcescontinuous monitoring and assessment is necessary.
Subarnarekha River is one of the most important east flowing interstate rivers ofIndia with a total catchment area of about 19, 296km2. It flows through threeIndian states viz. Jharkhand, West Bengal and Odisha covering a distance ofaround 470km. According to the Subarnarekha Barrage Project a barrage is to beconstructed near Bhasraghat (West Medinipore district, West Bengal) to irrigate1,14,198h of land annually through a left bank canal and its distribution systemcovering a cultural command area of 96,860h (http:/ /pib. nic. in/ newsite /erelease.Aspx ?relid =33636). Moreover, Government of Odisha also plans to developdeep water; all weather port at Kirtania near the mouth of the Subarnarekha Riverfor which a memorandum of understanding with a Chennai based company hasbeen signed (http:// www. orissadiary. com/ Show Bussiness News. asp?id=3556).Based on these important developmental activities pre-projects level study of theriver water becomes necessary to compare with any future studies of the region.
Environmental monitoring and assessment of freshwater resources provide
feedback on the status of their quality degradation based on performance of
developmental programmes and projects. The major objectives of the present
study were to collect the most recent physicochemical data of the Subarnarekha
river in West Bengal and Odisha to develop water quality index (WQI) indicating
the ecological status of the surface water and apply chemometrics, which uses
multivariate statistical modeling, like principal component analysis (PCA) /factor
analysis (FA) and agglomerative hierarchical cluster analysis (AHCA) to further
interpret the surface water quality data. Suitability of water for irrigation was also
tested using indices like sodium adsorption ratio (SAR), percentage sodium (%Na)
and permeability index (PI) including salinity graphics.
MATERIALS AND METHODS
Study area
The study area consisted of two districts West Medinipore (21º36´ to 22º57´ N
and 86º33´ to 88º11´E) and Balasore (21º03' to 21º59' N and 86º20' to 87º29'
NSave Nature to Survive QUARTERLY
Subarnarekha River is one of the most impor-
tant east flowing rivers of India. The river in
West Bengal and Odisha is site for the
Subarnarekha Barrage Project and Kirtania port
respectively. The major objectives of the
present study were to investigate the pre-
projects level water quality of the river basin
through development of water quality index
(WQI) and application of chemometrics. Suit-
ability of water for irrigation was also tested
using sodium adsorption ratio (SAR), percent-
age sodium (%Na) and permeability index (PI).
Most of the parameters were found to be
within the permissible limits of prescribed stan-
dards. WQI classified river water into good
and medium reflecting the water to be eco-
logically suitable and sustainable.
Chemometrics further helped in clear inter-
pretation of the water quality. SAR, %Na and
PI indices displayed water to be suitable for
irrigation. The river water was found to be
ecologically suitable and sustainable because
of absence of any major anthropogenic influ-
ence in the region as compared to upper in-
dustrial and populated belts like Jamshedpur
and Ghatsila in Jharkhand state. This study
can be used as reference to observe the status
of quality of water during ongoing projects
and post projects scenario.
ABSTRACT
*Corresponding author
323
E) lying in the Indian states of West Bengal and Odisha
respectively (Fig. 1). The western portion of the West
Medinipore is a part of the Chottanagpur plateau formed of
hard lateritic stone. The eastern portion is a part of the coastal
plain and is formed of alluvial soil. Subarnarekha River flows
through the upland region of the western portion of the district.
Balasore district is a coastal district of the Odisha situated on
the northern most part of the state. It is bounded by West
Medinipore on its north and by the Bay of Bengal on the east.
Subarnarekha River flows through the north-western hills, inner
alluvial plain and the coastal belt before draining into the Bay
of Bengal near Talsari. The climate of the study area is mostly
hot and humid. Summer season starts from middle of March
and continues till May. Rainy season lies from June to
September with South-western monsoon causing maximum
rain. However, maximum rain is experienced during the July-
August period. The region experiences winter season from
December to February (http:/ /www. indianetzone. com/5/
balasore. htm).
Sampling procedure and preservation
Water samples were collected from thirteen locations along
the route of the Subarnarekha River basin in West Medinipore
and Balasore districts (Fig. 1) during post-monsoon, October
2011, period and analysed for their physicochemical
properties. Standard procedures as described by APHA (2005)
were followed for the Sample collections, stabilisation and
transportation to the laboratory as well as storage. All the
samples were processed within 6 hours of their collection.
Sample analyses
Water samples were analysed for nineteen parameters to
determine the overall quality with respect to pH, temperature
(Temp), dissolved oxygen (DO), electrical conductivity (EC),
total suspended solids (TSS), total dissolved solids (TDS),
bicarbonate (HCO3
-), hardness (Hard), calcium (Ca2+),
magnesium (Mg2+), biological oxygen demand (BOD),
chemical oxygen demand (COD), nitrate (NO3
-), phosphate
(PO4
-3), fluoride (F-), chloride (Cl-), sulphate (SO4
-2), sodium
(Na+) and potassium (K+) following the methods described by
APHA (2005). Temp, pH and DO were measured on the field.
All the reagents were of analytical grade purchased from
Merck, India. To prepare all the reagents and calibration
CHARACTERISATION OF THE SUBARNAREKHA RIVER WATER
standards double glass distilled and deionised waters were
used.
Basic statistical and correlation analyses
Descriptive statistics of the studied physicochemical variables
for all studied sampling sites was determined. Correlation
analysis using Pearson correlation matrix was done to
determine the interrelationship between the variables.
Water quality index (WQI) determination
WQI was determined following Pesce and Wunderlin (2000).
WQI =
Where,
k = subjective constant and represents the visual impression
of the river. Its value ranges from 0.25 to 1.00. k = 0.25 for
highly contaminated water, 0.5 for moderately contaminated
water, 0.75 for light contaminated water and 1.00 for apparently
good quality water. Ci and Pi are normalised and relative weight
values assigned to each parameter respectively (values of Ci
and Pi can be obtained from the paper authored by Pesce and
Wunderlin (2000). Higher relative weight has been assigned
to the parameters (like DO = 4) considered most important for
the aquatic. Whereas, parameters considered least important
have been assigned comparatively lower relative weights (like
temperature and pH = 1). To do away with the subjective
evaluation of the water quality, constant k was not considered
in the present study. Similar provisions have also been used
by authors like Abrahão et al. (2007) and Sánchez et al. (2007).
The value of WQI ranges from 0 – 100 which can be classified
into five categories. WQI values between 0 – 25 classified as
“very bad”; WQI values between 26 – 50 classified as “bad”;
WQI values between 51 – 70 classified as “medium”; WQI
values between 71 – 90 classified as “good” and WQI values
between 91 – 100 classified as “excellent” (Jonnalagadda and
Mhere, 2001; Sánchez et al., 2007).
Agglomerative hierarchical cluster analysis (AHCA)
Cluster analysis (CA) is one of the most important multivariate
statistical methods for sorting objects into groups or clusters. It
is an exploratory data analysis tool for solving classification
problems. Members of the same cluster have strong degree of
association as compared to the members belonging to the
other clusters (Kašparová et al., 2009). CA can be done using
Figure 2: Piper trilinear diagram of major ions in river waterCations Anions
Mg
2+
SO4
2- +
Cl-
CO
32- +
HC
O3
-
Ca2+
+ M
g2-
SO4 2-
Na+
+K+
Cl -Ca2+
S.1
S.2
S.3
S.4
S.5
S.6
S.7
S.8
S.9
S.10
S.11
S.12
Explanation
Figure 1: Study area and the sampling sites
S.1 Gopiballabhpur
S.2 Bhasraghat
S.3 Sonakanla
Rajghat S.4S.5 Baliapal Branch
S.6 Asti
S.7 PantaiJamkunda
S97Batagramcanal
S.10 Kirtanla
S.11 Kirtanla muhana
S.13DighaNalah
Bay ofBengal
Talsari S.12S.8 Bhusandeswar
WestBengal
Sampling sites along the subarnarekha river basin
Sampling sites in west medinipore
district
Sampling sites in balasore district
West Bengal
India
Odisha
Odisha
∑
∑
i
i
Pi
CiPi
k
324
both hierarchical and non-hierarchical methods. In this study
AHCA was performed for sorting variables into easily
explainable clusters using Ward’s method and squared
Euclidean distance as a distance measure. Hierarchical
agglomerative techniques start from the finest possible structure
(each data point forms a cluster), compute the distance matrix
for the clusters and join the clusters that have the smallest
distance. This step is repeated until all points are united in
one cluster (Härdle and Simer, 2003).
Principal component analysis (PCA)
The main objective of the PCA is to reduce the dimension of
the observations while retaining the variability in the
multivariate dataset. Low dimensional linear combinations are
often easier to interpret which makes the complex data analysis
easier (Härdle and Simer, 2003). PCA can be performed on
the correlation or covariance matrix of the dataset. Principal
components are the smaller set of independent or uncorrelated
variables obtained by transforming a larger set of inter-
correlated variables. These components provide useful
information on the most significant parameters that explain
the variability in the full dataset while excluding the less
significant ones (Juahir et al., 2011). The principal component
is expressed as:
KUMAR MANOJ et al.,
Figure 6: USSL diagram for classification of river waters for irrigation
So
diu
m h
azard
Low
Hig
hM
ed
ium
So
diu
m A
bso
rpti
on
Rati
o (SA
R)
Very
High
Conductivity (μS/cm)
Very HighHighMediumLow
Salinity hazard
Figure 5: Gibbs plot for TDS versus Na+: (Na+ + Ca2+)
Rock WeatheringDominance
Evaporation CrystallizationDominance
Precipitation/RainDominance
Na+: (Na+ + Ca2+)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
TD
S (m
g/L
)
TD
S (m
g/L
)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Cl-: (Cl- + HCO3
-)
Figure 4: Gibbs plot for TDS versus Cl-: (Cl- + HCO3
-)
Rock WeatheringDominance
Evaporation CrystallizationDominance
Precipitation/RainDominance
Figure 3: Agglomerative hierarchical cluster analysis depicted as
dendrogram
EC TDS HCO3
-T SO4
-2 F - TSS K+ DO Hard Mg2+ pH Ca 2+NO3
- PO4
3- BOD C O D Cl -Na+
Resc
ale
d d
ista
nce c
lust
er
co
mb
ine
Figure 7: Wilcox diagram for classification of river waters for
irrigation
Conductivity (μS/cm)
Excell
en
t to
Go
od
Go
od
to
Perm
issi
ble
Un
suit
ab
le
Do
ub
tfu
l to
Perm
issi
ble
Perc
en
tage o
f so
diu
m (%
Na)
mjim
...........
3ji32ji21ji1ij xaxaxaxaZ ++++=Where z is the component score, a is the component loading,
325
Table 1: Physicochemical properties of the water samples
Parameters Sampling sites
S.1 S.2 S.3 S.4 S.5 S.6 S.7 S.8 S.9 S.10 S.11 S.12 S.13
pH 7.20 7.40 7.80 7.50 7.80 7.30 7.70 7.30 7.60 7.90 7.90 7.70 8.20
Temp (ºC) 27.0 26.80 26.90 27.10 27.50 27.30 26.90 27.10 27.30 27.30 27.10 26.80 27.80
DO (mg/L) 5.60 5.90 5.80 5.20 5.60 5.30 5.10 4.60 4.70 4.90 5.20 5.50 6.50
EC (μS/cm) 456.00 453.00 447.00 493.00 475.00 439.00 394.00 528.00 504.00 436.00 462.00 427.00 792.00
TSS (mg/L) 100.00 150.00 152.00 116.00 103.00 123.00 149.00 135.00 147.00 112.00 152.00 264.00 510.00
TDS (mg/L) 296.00 292.00 286.00 325.00 304.00 283.00 251.00 342.00 323.00 281.00 295.00 284.00 519.00
HCO3
- (mg/L) 40.10 36.40 33.40 45.10 33.00 25.20 32.50 34.00 51.3 24.00 36.00 20.00 99.10
Hard (mg/L) 62.79 77.45 78.92 101.09 89.70 80.01 61.43 69.84 75.33 97.00 72.00 96.00 96.50
Ca2+ (mg/L) 33.56 35.56 32.56 45.00 40.20 34.67 25.56 22.50 36.00 37.00 16.00 36.00 36.50
Mg2+ (mg/L) 7.10 10.18 11.27 13.63 12.03 11.02 8.72 11.50 9.56 14.58 13.61 14.58 14.58
BOD (mg/L) 0.56. 3.76 2.96 1.10 0.93 1.87 1.59 2.80 2.24 1.51 3.39 0.54 1.88
COD (mg/L) 9.00 160.00 86.00 45.00 35.00 77.00 67.00 141.00 120.00 112.00 168.00 16.00 98.00
NO3
- (mg/L) 1.78 1.10 1.23 1.10 0.44 0.44 0.86 0.59 0.44 0.43 0.40 0.46 0.54
PO4
3- (mg/L) 3.76 1.76 1.80 1.46 1.50 1.50 1.00 0.86 1.50 2.10 2.40 0.80 2.90
F- (mg/L) 0.10 0.15 0.11 0.19 0.22 0.26 0.29 0.23 0.20 0.15 0.12 0.21 0.30
Cl- (mg/L) 36.11 31.65 35.06 30.12 30.34 29.23 33.00 39.10 36.20 35.10 35.12 35.00 35.20
SO4
3- (mg/L) 109.00 115.00 110.00 144.23 141.30 138.54 105.00 163.00 123.23 128.00 112.00 128.00 176.00
Na+ (mg/L) 43.68 40.26 43.06 36.56 34.45 38.34 45.00 68.70 74.64 33.00 35.00 11.80 66.30
K+ (mg/L) 33.33 35.56 32.56 23.12 29.45 21.03 12.56 9.10 7.12 25.00 49.50 46.12 95.20
Table 2: Use of water as proposed by *CPCB and #BIS.
Classification of water for different uses designated by CPCB
Designated best use Class of water Criteria
Drinking water source without A pH between 6.5 – 8; DO 6 mg/L or more;
conventional treatment but after disinfection BOD at 20ºC 2 mg/L or less
Outdoor bathing (organized sector) B pH between 6.5 – 8.5; DO 5 mg/L or
more; BOD at 20°C 3 mg/L or less
Drinking water source after conventional C pH between 6 – 9; DO 4 mg/L or more;
treatment and disinfection BOD at 20°C 3 mg/L or less
Propagation of wild life and fisheries D pH between 6.5 – 8.5; DO 4 mg/L or
more; Free ammonia (as N) 1.2 mg/L or less
Irrigation, industrial cooling, E pH between 6.0 – 8.5 mg/L or less; Electrical
controlled waste disposal conductivity at 25ºC μmhos/cm maximum 2250
Indian standard specifications for the tolerance levels for palatability; BIS; IS:10500; 2004
Parameters Desirable limit Undesirable effect outside the desirable Permissible limit
limit
Cl- 250 Beyond this limit taste, corrosion and 1000
palatability are affected
Ca2+ 75 Encrustation in water supply structure 200
and adverse effects on domestic use
Mg2+ 30 Encrustation in water supply structure and 100
adverse effects on domestic use
NO3
- 45 Beyond this methaemoglobinemia takes No relaxation
place/ may be indicative of pollution
SO4
2- 200 Beyond this causes gastro-intestinal irritation 400
TDS 500 Beyond this palatability decreases 2000
and may cause gastro-intestinal irritation
Hardness 300 Encrustation in water supply structure and 600
adverse effects on domestic use*Central Pollution Control Board; # Bureau of Indian Standard
x is the measured value of the variable, i is the component
number, j is the sample number, and m is the total number of
variables. In this study PCA was performed using correlation
matrix among the variables. VARIMAX normalised rotation
was applied to make the results more interpretable as rotated
component matrix helps to clarify the doubts which may be in
the original component matrix (Hani, 2010).
Suitability of river water for irrigation
Sodium adsorption ratio (SAR), percentage sodium (%Na) and
permeability indices were used to assess the suitability of the
Subarnarekha River water for irrigation. The ions used for
calculating these indices were first converted into
miliequivalent (meq)/L from mg/L.
meq/L =
Sodium hazard is typically expressed as SAR. This index
describes the concentration of sodium in relation to the
combined concentrations of calcium and magnesium. SAR
was calculated as given below (USSL, 1954):
weightequivalent
mg/L
CHARACTERISATION OF THE SUBARNAREKHA RIVER WATER
326
SAR =
Table 3: Descriptive statistics for the studied physicochemical parameters
Parameters Min Max Mean SD Median Variance Skewness Kurtosis
pH 7.20 8.20 7.64 0.29 7.70 0.084 0.176 -0.488
Temp 26.80 27.80 27.14 0.29 27.10 0.084 0.878 0.658
DO 4.60 6.50 5.38 0.52 5.30 0.272 0.513 0.430
EC 394.00 792.00 485.08 98.58 456.00 9718.58 2.848 9.170
TSS 100.00 510.00 170.23 110.13 147.00 12129.69 2.864 8.702
TDS 251.00 519.00 313.92 65.82 295.00 4331.91 2.854 9.218
HCO3
- 20.00 99.10 39.24 19.85 34.00 393.98 2.545 7.708
Hard 61.43 101.09 81.39 13.44 78.92 180.73 0.062 -1.318
Ca2+ 16.00 45.00 33.16 7.67 35.56 58.85 -0.991 1.074
Mg2+ 7.10 14.58 11.72 2.41 11.50 5.83 -0.391 -0.720
BOD 0.54 3.76 1.93 1.05 1.87 1.09 0.338 -0.938
COD 9.00 168.00 87.23 52.23 86.00 2727.86 0.036 -1.065
NO3
- 0.40 1.78 0.75 0.43 0.54 0.185 1.313 1.138
PO4
3- 0.80 3.76 1.79 0.84 1.50 0.701 1.134 1.323
F- 0.10 0.30 0.19 0.07 0.20 0.004 0.115 -1.050
Cl- 29.23 39.10 33.94 2.87 35.06 8.25 -0.220 -0.549
SO4
2- 105.00 176.00 130.25 21.75 128.00 473.01 0.876 0.099
Na+ 11.80 74.64 43.91 17.03 40.26 289.96 0.378 0.364
K+ 7.12 95.20 32.28 22.89 29.45 524.14 1.791 4.436
river. BOD slightly exceeded the permissible limit (class ‘A’
range d” 2.0 mg/L) at sites S.2, S.3, S.8, S.9 and S.11 prescribed
by Central Pollution Control Board (CPCB, 2008). Readings of
DO and BOD point to moderate organic pollution load of the
river. This is expected as the river water is used for washing,
fishing, bathing, domestic waste disposal etc. Very low
concentrations of fluoride were obtained in the river water.
The standards of BIS and CPCB are given in Table 2.
Interpretation of hydrochemical regime
To better understand the hydrochemical regime of the studied
region some major ions determined in the water samples were
plotted on the Piper diagram (Piper, 1994). The Piper trilinear
diagram for important sampling sites of the Subarnarekha River
is displayed in Fig. 2. The diagram consists of two lower
triangles and a middle quadrilateral. The left and right triangles
represent the distribution of major cations and major anions
respectively. The quadrilateral summarises the dominant
cations and anions to indicate the final water type. The water
types are designated according to the area in which they occur
on the diagram segments (Tatawat and Chandel, 2007). The
distribution of cations indicates samples from five locations to
be of no dominant type and samples from the remaining sites
to be of Na+-K+ type. In anion distribution triangle samples
from all locations fall under zone representing SO4
2- type with
a small number of samples plotted very close to the no
dominant type water. Two distinct water types can be identified
from the Piper diagram. Samples from S.4, S.5, S.6, S.10 and
S.12 sites is classified into Ca2+-Mg2+-SO4
2--Cl- water type
whereas, samples from S.1, S.2, S.3, S.7. S.8, S.9 and S.11
belong to Na+-K+-Cl--SO4
2- water type.
Basic statistical analyses
Basic statistics for the water quality of the Subarnarekha River
is given in Table 3. Skewness values indicate parameters like
EC, TDS, Ca2+, Mg2+and Cl- to be negatively and moderately
skewed. Parameters like DO, TSS, BOD, NO3
-, PO4
3- and SO4
2-
are found to be positively and moderately skewed. Thus, we
can say that the concentrations of the parameters are not
uniformly distributed which can also be confirmed by their
high variance values.
KUMAR MANOJ et al.,
PI =
%Na is also used to evaluate sodium hazard as water with
higher %Na may result in sodium accumulations which can
cause undesirable changes in the physical properties of the
soil and reduce soil permeability. %Na was obtained from the
equation given below (Wilcox, 1955):
[ ][ ]
2
MgCa
Na
22 ++
+
+
Permeability index (PI) is used to assess probable influence ofwater quality on the physical properties of soil. Long timeeffects of irrigation water quality on physical properties of soildepend mainly on total salts, Na+, HCO
3
- and CO3
-
concentrations of irrigation water and on initial soil properties(Kirda, 1997). The PI was calculated from the equationprovided below (Doneen, 1964):
x100KNaMgCa
KNa22 ++++
++
++++
%Na =
RESULTS AND DISCUSSION
Physicochemical characterisation
Physicochemical characterisation of surface water bodies
widely reflects the pollution load and anthropogenic influence
on the water systems (Suthar et al., 2009). The results obtained
for nineteen physicochemical parameters in this study are
presented in Table 1. The pH range indicates moderately
alkaline water of river Subarnarekha. Temperature did not
vary much among the sampling sites. Electrical conductivity
of the Subarnarekha river water was significantly different along
the basin route. Similar results were obtained for TDS and
TSS. Hardness values indicate relatively soft nature of river
water. Concentration of Cl; SO4
2-, NO3
-, Ca2+ and Mg2+ were
found to be within the permissible limits of Bureau of Indian
Standards (BIS, 2004). DO values were less than the regulatory
standard (e” 6.0 mg/L) at most of the sampling sites. DO levels
are important in the natural self-purification capacity of the
x100NaMgCa
HCONa
22
3
+++
−+
++
⎟⎠
⎞⎜⎝
⎛ +
327
Tab
le 4
: C
orr
ela
tio
n a
naly
sis
of
the s
tud
ied
ph
ysi
co
ch
em
ical
para
mete
rs
pH
Tem
pD
OEC
TSS
TD
SH
CO
3
-H
ard
Ca2
+M
g2+
BO
DC
OD
NO
3
-PO
4
3-
F-
Cl-
SO4
2-
Na
+K
+
pH
10
.48
10
.37
00
.45
50
.60
8*
0.4
45
0.4
45
0.4
64
-0.0
10
0.6
35
*0
.03
70
.14
4-0
.46
10
.11
10
.19
00
.08
10
.19
2-0
.03
20
.62
5*
Tem
p1
0.2
11
0.7
32
**
0.4
64
0.7
16
**
0.6
51
*0
.39
90
.25
50
.34
2-0
.16
50
.04
3-0
.46
80
.29
80
.45
7-0
.07
00
.69
6*
*0
.42
90
.41
1
DO
10
.49
40
.63
5*
0.5
00
0.5
26
0.2
71
0.2
96
0.1
38
-0.0
09
-0.1
97
0.2
81
0.4
68
0.0
44
-0.2
50
0.1
45
-0.1
42
0.8
18
**
EC1
0.8
28
**
0.9
98
**
0.9
36
**
0.3
36
0.1
37
0.3
49
0.0
60
0.1
58
0.1
69
0.3
56
0.4
15
0.2
30
0.7
68
**
0.5
70
*0
.70
6*
*
TSS
1-0
.83
9*
*0
.77
8*
*0
.37
20
.07
00
.44
9-0
.01
80
.03
1-0
.23
70
.20
30
.48
50
.20
30
.54
30
.23
00
.84
9*
*
TD
S1
0.9
30
**
0.3
64
0.1
61
0.3
69
0.0
30
0.1
28
0.1
60
0.3
47
0.4
18
0.2
25
0.7
79
**
0.5
41
*0
.71
6*
*
HC
O3
-1
-0
.19
70
.15
60
.14
60
.06
70
.12
70
.00
80
.45
70
.35
60
.15
80
.54
6*
0.6
15
*0
.66
3*
Hard
10
.68
3*
0.8
26
**
-0.3
27
-0.2
07
-0.3
54
-0.1
14
0.1
55
-0.3
15
0.5
20
-0.3
30
0.3
98
Ca2
+1
0.1
52
-0.5
21
-0.5
25
0.1
44
0.0
13
0.0
90
-0.5
03
0.2
48
-0.1
67
0.0
54
Mg
2+
1-0
.04
00
.12
5-0
.59
1*
-0.1
65
0.1
40
-0.0
38
0.5
11
-0.3
18
0.4
96
BO
D1
0.9
08
**
-0.0
88
-0.0
68
-0.2
18
0.1
73
-0.1
20
0.3
48
0.0
02
CO
D1
-0.3
34
-0.0
54
-0.1
08
0.2
74
0.0
36
0.4
19
0.0
03
NO
3
-1
0.4
59
-0.4
89
0.0
15
-0.4
08
-0.0
23
-0.0
68
PO
4
3-
1-0
.41
90
.16
4-0
.08
80
.12
50
.51
3
F-
1-0
.20
40
.58
7*
0.2
85
0.1
11
Cl-
10
.05
60
.44
70
.05
2
SO4
2-
10
.37
70
.35
7
Na
+1
-0.0
72
K+
1*. C
orr
elat
ion is
sig
nific
ant a
t the
0.0
5 le
vel (
2-tai
led); *
*. C
orr
elat
ion is
sig
nific
ant a
t the
0.0
1 le
vel (
2-tai
led).
Correlation analysis
Correlation coefficients obtained between different
physicochemical parameters is presented in Table 4. Most of
the components show good correlation among themselves
indicating interrelationships and interactions between the
parameters. DO show positive correlation with TSS and K,
whereas negative correlation is obtained between DO and
TDS. TDS and conductivity reveal to be most significantly
correlated. Highly significant relationships are shown by ions
like SO4
2-, Na+ and K+ on the overall conductivity of water.
TSS reveals positive correlation with HCO3
- and K+ and negative
correlation with TDS. Total hardness displays highly significant
relationship with Ca2+ and Mg2+. As expected, BOD and COD
showed significantly high positive correlation.
Water quality index determination
WQI was determined involving fifteen parameters which were
normalised and weighted prior to index calculation. WQI
calculated at different locations along the river basin is shown
in Table 5. WQI value ranged from 61.72 to 78.28 with
minimum and maximum values recorded at S.13 and S.1
respectively. Overall the WQI values can be categorised into
two categories viz. medium and good. Since, River
Subarnarekha is a part of the national river action plan (India)
WQI can be successfully applied for its overall classification
and characterization. WQI can be an effective tool of water
quality characterisation and trend analysis as it is easily
understandable to the general public, policy makers and
regulatory bodies.
Agglomerative Hierarchical cluster analysis
Chemometrics uses multivariate statistical modeling techniques
like AHCA and PCA for exploratory data analysis. This can be
regarded as an analytical branch of environmental chemistry
for better interpretation of data matrix. Cluster analysis was
applied to the standardised water quality dataset for multivariatestatistical modeling using Ward’s method and squaredEuclidean distances as criteria for forming clusters of thevariables. The AHCA dendrogram displaying clustering of thestudied physicochemical parameters is plotted in Fig. 3. Fourclusters are observed from the dendrogram each of themfurther subdivided into sub-clusters. EC, TDS, HCO
3
-, Temp,SO
4
2- and F- showing very high correlations among themselvesform cluster 1. Similarly TSS, K+ and DO being significantlycorrelated form cluster 2. The third group is dominated mainly
Table 5: WQI and classification of the river waters
Sampling sites WQI Values Water Classification
S.1 78.97 Good
S.2 66.21 Medium
S.3 68.28 Medium
S.4 74.48 Good
S.5 75.52 Good
S.6 71.03 Good
S.7 72.07 Good
S.8 65.17 Medium
S.9 66.89 Medium
S.10 68.62 Medium
S.11 65.52 Medium
S.12 74.83 Good
S.13 62.41 Medium
CHARACTERISATION OF THE SUBARNAREKHA RIVER WATER
328
Table 6: Rotated component matrix of the water quality data
Parameters Principal Components
1 2 3 4 5 6 Communalities
pH 0.158 0.531 0.615 0.088 -0.083 0.161 0.725
Temp 0.789 0.117 0.311 -0.067 -0.066 -0.097 0.751
DO 0.125 0.883 -0.034 -0.060 0.189 -0.332 0.946
EC 0.862 0.463 0.156 0.056 0.014 0.065 0.989
TSS 0.502 0.750 0.240 -0.046 -0.195 0.149 0.935
TDS 0.854 0.468 0.170 0.023 0.014 0.057 0.981
HCO3
- 0.807 0.523 -0.041 0.065 0.082 0.019 0.938
Hard 0.222 0.114 0.795 -0.257 0.033 -0.443 0.958
Ca2+ 0.245 -0.051 0.172 -0.484 0.173 -0.724 0.880
Mg2+ 0.112 0.194 0.943 0.026 -0.090 -0.040 0.950
BOD -0.022 0.048 -0.086 0.979 0.036 0.069 0.974
COD 0.138 -0.087 0.118 0.945 -0.002 0.190 0.970
NO3
- -0.167 0.133 -0.645 -0.205 0.582 -0.124 0.858
PO4
3- 0.244 0.405 -0.178 -0.078 0.744 0.109 0.827
F 0.448 0.144 -0.015 -0.170 -0.847 -0.087 0.975
Cl 0.213 -0.069 -0.004 0.071 0.216 0.889 0.893
SO4
2- 0.790 0.033 0.348 -0.093 -0.261 -0.088 0.832
Na+ 0.782 -0.155 -0.378 0.322 -0.044 0.264 0.953
K+ 0.279 0.876 0.319 -0.011 0.156 0.036 0.973
Eigenvalues 4.826 3.407 2.977 2.373 1.883 1.843
% variance 25.399 17.932 15.666 12.489 9.911 9.701
explained by
component
Cumulative 25.399 43.331 58.997 71.487 81.398 91.099
% varianceExtraction method: Principal component analysis
Table 7: Major ions and salinity indices
Sampling sites Na+ (meq/L) K+ (meq/L) Ca2+ (meq/L) Mg2+ (meq/L) HCO3
-(meq/mL) SAR %Na PI
S.1 1.90 0.85 1.68 0.59 0.66 1.78 54.78 64.99
S.2 1.75 0.91 1.78 0.85 0.60 1.52 50.28 57.53
S.3 1.87 0.83 1.63 0.94 0.55 1.65 51.23 58.78
S.4 1.59 0.59 2.25 1.14 0.74 1.22 39.14 49.20
S.5 1.50 1.28 2.01 1.00 0.54 1.22 48.01 49.45
S.6 1.67 0.54 1.73 0.92 0.41 1.45 45.47 53.47
S.7 1.96 0.32 1.28 0.73 0.53 1.96 53.15 67.76
S.8 2.99 0.23 1.13 0.96 0.56 2.93 60.64 73.62
S.9 3.25 0.18 1.80 0.80 0.84 2.85 56.88 71.28
S.10 1.43 0.64 1.85 1.22 0.39 1.46 40.27 45.56
S.11 1.52 1.27 0.80 1.13 0.59 1.24 59.11 66.38
S.12 0.51 1.18 1.80 1.22 0.33 1.41 35.88 30.59
S.13 2.88 2.44 1.83 1.22 1.62 0.76 63.56 69.98
by Hard, Ca2+ and Mg2+ which is expected as these ions have
highly significant impact on the hardness property. In cluster
4 three sub-clusters are observed: NO3
- - PO4
3-, BOD - COD
and Cl- - Na+. Clustering of NO3
- - PO4
3- and Cl- - Na+ reflects
potential interaction among the ions.
Principal component analysis
PCA was applied to the water quality dataset obtained for the
Subarnarekha River water to more accurately evaluate the
clustering behaviour. VARIMAX rotation with Kaiser
Normalisation was used for this intelligent data analysis
technique for better interpretation of the results. The result of
PCA is displayed in Table 6. Six principal components (PC)
were obtained with a cumulative variance of 91%. PC 1
accounts for 25% of the total variance and is dominated by
EC, TDS, HCO3
-, Temp, SO4
2- and Na+ with very high factor
loadings. PC 2 accounts for 18% of the total variance and is
dominated by TSS, K+ and DO with significantly higher factor
loadings. PC 3 is dominated by Hard and Mg2+ accounting for
16% of the total variance. PC4 is loaded by BOD and COD
accounting for 12% of the total variance. PC 5 accounts for
around 10% of the total variance and is highly contributed by
NO3
- and PO4
3-. PC 6 also accounting for around 10% of the
total variance is loaded with Cl- ion. Though Na+ and Cl- ions
were clustered in AHCA, because of relatively good
interrelationship between them, in PCA they belong to different
principal components. The concentrations of Cl ion did not
vary much along the river route but wide variations in Na+
values were noted. This could be the possible reason for their
separation in PCA. Analytical chemical data of the water
samples can be used to assess the functional sources of
dissolved ions in waters. High positive loadings of HCO3
-,
SO4
2- and Na+ on PC 1 indicate these ions to be the principal
ions controlling the TDS and conductivity of the river water.
Similarly Mg2+ ions seem to be the most important ions
influencing hardness. These phenomena suggest various
hydrogeochemical processes affect the salinity behaviour of
river water. High positive loading of Na+ ion reflects ion
KUMAR MANOJ et al.,
329
exchange on the clay materials and the process of dissolution
of Na+ and Cl- suggest a higher rate of weathering (Bhardwaj
et al., 2010). High positive loadings for Na+ and Cl- ions were
obtained in PCA indicating weathering of rock minerals as
principal sources of these ions in river water. Similarly the
presence of HCO3
- ions can principally be attributed to the
dissolution of silicate minerals and its reaction with soil CO2.
However, the concentration of NO3
- and PO4
3- ions in water is
mainly attributed to the agricultural runoff which is also
indicated by their high factor loadings in PC 5. The areas
along the project sites are underdeveloped and lack major
industrial activities. These sites lie downstream of some
important industrial and populated belts of Jharkhand state
like Ranchi, Jamshedpur and Ghatsila.
The dominance of geogenic activities responsible for
dissolved ions is also confirmed by the Gibbs plot. According
to Gibbs (1970) evaporation-crystallisation, rock weathering
and precipitation are the three dominant processes that control
the water chemistry. The weighted ratios of Cl-: (Cl- + HCO3
-)
and Na+: (Na+ + Ca2+) plotted as a function of TDS in Gibbs
plot (Fig. 4 and Fig. 5) reveal the ionic composition of waters
to be mainly controlled by the rock weathering processes.
Suitability of river water for irrigation
The calculated values of SAR, %Na and PI are displayed inTable 7. SAR index is typically used to express sodium hazardin more reliable manner. According to Todd (1980) waterswith SAR values < 10 are excellent for irrigation related works.Presence of excess Na+ in the irrigation water is hazardous asit can replace adsorbed Ca2+ and Mg2+ from the soils makingthem more compact and impervious. This tendency of irrigationwaters to enter into cation exchange reactions with soil can bepredicted using SAR. In this study SAR values vary from 0.76to 2.93 indicating suitability of the river water for irrigation.Salinity hazard for crop productivity is measured in terms ofelectrical conductivity. Higher the conductivity less is the wateravailable for use by the plants. Waters with conductivity from250 – 750 μS/cm are considered well for irrigation whereas,waters with conductivity > 750 μS/cm are considereddoubtful. All major sampling sites from S.1 to S.12 in thisstudy display conductivity to be < 750 μS/cm showing thesuitable nature of the river water for irrigation. The United
States Salinity Laboratory (USSL, 1954) diagram describes
relation between SAR and conductivity of water samples and
places them into irrigation water categories based on the
combination of the two parameters (Anim et al., 2011). Salinity
diagram for the Subarnarekha River is displayed in Fig. 6. It is
observed that all major sites from S.1 to S.12 sites fall into
C2S1 category and only S.13 site come under C3S1 category.
This indicates suitability of the river water for irrigation and
other agricultural activities. In case of TDS, waters with TDS <
1000mg/L are considered best for irrigation related activities.
TDS at much higher concentrations may prove injurious to
the plants by altering osmotic activities and preventing
adequate aeration. All sampling sites from S.1 to S.12 showed
TDS to be < 1000mg/L. Plotting %Na against conductivity,
designated as Wilcox diagram (Fig. 7), can also be used for
water classification varying from excellent to unsuitable
(Wilcox, 1955). From Fig. 7 it becomes clear that the river
water comes under excellent to good category. Waters can be
classified as Class I, Class II and Class III based on PI values.
Class I and II waters are categorised as good for irrigation
having PI values of 75% or more. Class III waters are
categorised unsuitable with 25% maximum permeability
(Nagaraju et al., 2006). PI values in the present study were
obtained from 30.59 – 73.62. Accordingly, the river water
samples can be categorised as belonging to Class II reflecting
the suitability of the Subarnarekha River water for irrigation
purposes.
CONCLUSIONS
WQI classified Subarnarekha River water along the project
sites into good and medium categories. Chemometrics
identified geogenic activities to be principally responsible for
the dissolved ions in the river water. Three important indices
SAR, %Na and PI along with USSL diagram and Wilcox diagram
revealed river water to be suitable for agriculture. These
arguments clearly show overall quality of the river water along
the project sites to be unpolluted and ecologically suitable
and sustainable. Continuous monitoring and assessment will
keep checking the pollution status of the river water during
and after completion of the projects. This study can be used
as reference to observe the status of quality of water during
ongoing projects and post projects scenario.
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