Table 1: Weight (Wi) and Relative Weight (RW) of the physicochemical parameters and drinking water quality standards (WHO 2011).
Parameter
|
Unit
|
WHO (2011)
|
Weight (Wi)
|
Relative weight (Rwi)
|
pH
|
|
6.5-8.5
|
4
|
0.08
|
EC
|
µS/cm
|
1000
|
4
|
0.08
|
Ca
|
mg/l
|
75
|
2
|
0.04
|
Mg
|
mg/l
|
50
|
2
|
0.04
|
Na
|
mg/l
|
200
|
3
|
0.06
|
K
|
mg/l
|
12
|
1
|
0.02
|
HCO3
|
mg/l
|
120
|
3
|
0.06
|
Cl
|
mg/l
|
250
|
2
|
0.04
|
SO4
|
mg/l
|
250
|
3
|
0.06
|
NO3
|
mg/l
|
50
|
5
|
0.09
|
F
|
mg/l
|
1.5
|
5
|
0.09
|
As
|
μg/l
|
0.01
|
5
|
0.09
|
Mn
|
μg/l
|
40
|
4
|
0.08
|
Mo
|
μg/l
|
70
|
3
|
0.06
|
Pb
|
μg/l
|
10
|
3
|
0.06
|
U
|
μg/l
|
15
|
4
|
0.08
|
|
|
|
∑Wi = 53
|
∑Rwi = 1.00
|
Table 2: Standard equations applied to calculate different irrigation water quality indices (Concentrations are in meq/l).
Indices
|
Formula
|
Source
|
Sodium Adsorption Ratio (SAR)
|
|
Richards (1954)
|
Sodium Percentage (Na %)
|
|
Doneen (1964)
|
Residual Sodium Carbonate (RSC)
|
|
Richards (1954)
|
Permeability Index (PI)
|
|
Doneen (1964)
|
Table 3: Desirable limit, assigned and relative weight for the IWQI parameters.
IWQI Parameter
|
Desirable limit
|
Assigned Weight (AWi)
|
Relative Weights (RWi)
|
EC
|
1500 (Bauder et al.2011))
|
4
|
0.31
|
SAR
|
18 (Richard (1954))
|
3
|
0.23
|
Na%
|
60 (Wilcox (1955))
|
3
|
0.23
|
RSC
|
2.5 (Eaton (1950))
|
1
|
0.08
|
PI
|
75 (Doneen (1964))
|
2
|
0.15
|
Table 4: Statistical description of physicochemical and trace elements in the ZLB and comparison with the standard drinking water quality limits (WHO 2011; US EPA 2003).
Parameter
|
Groundwater (n=55)
|
Standard value
|
% Samples >
Standard limit
|
Min
|
Max
|
Mean
|
SD
|
T (OC)
|
14.30
|
60.7
|
25.12
|
7.06
|
30.00*
|
0.15
|
pH
|
6.17
|
8.80
|
7.59
|
0.58
|
6.5─8.5*
|
0.09
|
EC (µS/cm)
|
38.75
|
6300.00
|
827.67
|
1127.72
|
1000.00*
|
0.22
|
TDS (mg/l)
|
25.00
|
4725.00
|
662.25
|
892.14
|
500.00*
|
0.36
|
Major ions (mg/l)
|
|
|
|
|
|
|
Ca2+
|
0.50
|
113.76
|
28.78
|
26.05
|
75.00*
|
0.05
|
Mg2+
|
bdl
|
33.44
|
7.28
|
6.44
|
50.00*
|
0.00
|
Na+
|
2.30
|
858.00
|
133.56
|
186.29
|
200.00*
|
0.25
|
K+
|
0.66
|
152.00
|
16.73
|
25.19
|
12.00*
|
0.42
|
HCO3-
|
43.60
|
2547.00
|
433.26
|
450.57
|
120.00*
|
0.85
|
Cl-
|
0.98
|
207.00
|
24.66
|
47.06
|
250.00*
|
0.00
|
SO42-
|
bdl
|
186.00
|
12.99
|
30.41
|
250.00*
|
0.00
|
NO3-
|
bdl
|
41.11
|
6.26
|
8.82
|
50.00*
|
0.00
|
F-
|
bdl
|
40.00
|
3.39
|
6.66
|
1.5.00*
|
0.44
|
Trace elements (μg/l)
|
Mn
|
bdl
|
466.00
|
37.62
|
80.07
|
40.00*
|
0.22
|
As
|
bdl
|
278.00
|
30.17
|
63.50
|
10.00*
|
0.20
|
U
|
bdl
|
43.90
|
4.73
|
8.92
|
15.00*
|
0.07
|
Mo
|
0.24
|
446.00
|
17.29
|
62.63
|
70.00*
|
0.05
|
Pb
|
bdl
|
71.70
|
4.10
|
10.20
|
10.00*
|
0.05
|
Cr
|
bdl
|
24.60
|
4.62
|
5.11
|
50.00*
|
0.00
|
V
|
0.20
|
147.00
|
12.16
|
25.96
|
NG
|
─
|
Ti
|
bdl
|
44.10
|
8.53
|
6.66
|
NG
|
─
|
Sr
|
4.63
|
400.00
|
118.59
|
83.12
|
400.00**
|
0.00
|
Li
|
bdl
|
451.00
|
34.20
|
79.92
|
700.00**
|
0.00
|
Rb
|
1.23
|
146.00
|
13.58
|
26.84
|
NG
|
─
|
Ba
|
bdl
|
291.00
|
17.32
|
49.82
|
700.00*
|
0.00
|
Zn
|
bdl
|
870.00
|
69.62
|
160.48
|
3000.00*
|
0.00
|
Co
|
bdl
|
2.30
|
0.55
|
0.37
|
100.00**
|
0.00
|
Ni
|
bdl
|
12.10
|
3.35
|
2.37
|
20.00*
|
0.00
|
Cu
|
bdl
|
21.50
|
2.24
|
3.19
|
2000.00*
|
0.00
|
Sc
|
2.00
|
47.00
|
11.53
|
7.84
|
NG
|
─
|
Ga
|
bdl
|
11.50
|
0.36
|
1.75
|
NG
|
─
|
Cd
|
bdl
|
0.79
|
0.08
|
0.12
|
3.00*
|
0.00
|
Sb
|
bdl
|
5.09
|
0.39
|
0.95
|
20.00*
|
0.00
|
Be
|
bdl
|
0.03
|
0.01
|
0.01
|
4.00**
|
0.00
|
Bi
|
bdl
|
0.54
|
0.54
|
─
|
NG
|
─
|
Note: NG (No Guidelines), bdl = below detection limit, "*" WHO (2011), "**" US EPA (2003)
Table 5: Categorization of groundwater samples of the ZLB for irrigation uses.
Parameters (meq/l)
|
Groundwater (n=55)
|
Range
|
Water quality class
|
% Samples
|
Min
|
Max
|
Average
|
STD
|
EC
|
38.75
|
6300.00
|
827.67
|
1127.72
|
<250
|
Excellent
|
0.25
|
250-750
|
Good
|
0.42
|
750-2000
|
Permissible
|
0.20
|
2000-3000
|
Doubtful
|
0.05
|
>3000
|
Unsuitable
|
0.07
|
SAR
|
0.13
|
237.39
|
14.80
|
38.30
|
<10
|
Excellent
|
0.73
|
10–18
|
Good
|
0.09
|
18–26
|
Doubtful
|
0.07
|
>26
|
Unsuitable
|
0.11
|
Na%
|
11.72
|
99.89
|
56.17
|
28.78
|
<20
|
Excellent
|
0.15
|
20–40
|
Good
|
0.22
|
40–60
|
Permissible
|
0.20
|
60–80
|
Doubtful
|
0.16
|
>80
|
Unsuitable
|
0.27
|
RSC
|
-1.66
|
41.22
|
5.10
|
7.84
|
<1.25
|
Suitable
|
0.38
|
1.25–2.5
|
Marginally suitable
|
0.18
|
>2.5
|
Unsuitable
|
0.44
|
PI
|
39.93
|
136.36
|
100.49
|
21.47
|
>75
|
Excellent
|
0.87
|
75-25
|
Good
|
0.11
|
<25
|
Doubtful
|
0.02
|
Table 6: Results of DWQI and IWQI and their percentages.
WQI range
|
Water quality class
|
Drinking use
|
Irrigation use
|
% of Samples
|
% of Samples
|
<50
|
Excellent
|
0.56
|
0.28
|
50-100
|
Good
|
0.20
|
0.46
|
100-200
|
Poor
|
0.15
|
0.15
|
200-300
|
Very poor
|
0.02
|
0.07
|
>300
|
Unsuitable
|
0.07
|
0.04
|