CHARACTERISTICS OF LAKE WATER, SEDIMENT
AND ITS IMPACT ON GROUNDWATER
Praveen Kumar S* and Santhaveerana Goud B**
* Environmental Engineering, Department of Civil Engineering, Bangalore University, Bangalore – 56.
** Department of Civil Engineering, Bangalore University, Bangalore – 56.
Allasandra and Bellandur lakes were considered for the present study. These
lakes are located in the outskirts of Bangalore City and cover an area of
21.06 and 365 hectares respectively. The lake water, sediment and a
groundwater sample near the lakes were collected and analysed for Cu, Pb,
Cd, Ni, Mn, Zn and Cr using Atomic Absorption Spectrophotometer (AAS).
Elevated concentrations of physico-chemical parameters were recorded in
the lake and groundwater. The heavy metal concentration in Allasandra lake
is well with in the limits and can be used for agricultural soils. The study
revealed that the lakes were polluted because of untreated municipal waste
water
entering the lakes, there by polluting the surface water. Spatial
distribution of BOD was analysed using GIS software.
INTRODUCTION:
Lakes in urban areas are available natural resources which provide several
beneficial uses for urban population such as harvesting rainwater, recharging
the ground water table, mitigation of floods, pisciculture, capacity to supply
water in emergencies such as fire fighting and plenty of recreational
opportunities such as boating, swimming, walking and jogging in the lake
bund. .
Lakes are often seen as main targets for development in urban areas due to
pressure of human activities like urbanisation, industrialisation etc. As a
result of these activities most of the urban lakes are getting degraded beyond
the point of recovery. Encroachments, siltation, weed infestation, discharge
of domestic sewage, industrial effluents, surface run off carrying pesticides
and other chemicals used in agriculture are the main cause for degradation of
these lakes. The overall impact of these activities has resulted in
1. Deterioration of lake water quality
2. Sedimentation and shrinkage
3. Increase in mosquito breeding causing health hazards
4. Increase in productivity to support flora and fauna
5. Loss of aesthetic values and decrease in tourism potential
Description:
Two lakes namely Allalasandra and Bellandur lakes were selected for
the study. They are located between 77 35’ and 13 05’ and 77 40’ and 13
55’ respectively. The water spread area of the Allalasandra lake is 16.84
hectares and Bellandur lake is 365 hectares. The maximum depth at the
deepest point is 1.5 m in Allalasandra and Bellandur lake is 5 m . The
capacity of Allalasandra lake is 0.43 MCM (Million cubic meter) and
Bellandur lake is 17.67 MCM.
The total quantity of wastewater from the catchment area due to
different activities such as domestic and commercial was about 10 MLD
entering into the Allalasandra lake.
The quantity of wastewater from the catchment area entering
Bellandur lake is about 62 MLD i.e., from C valley 22 MLD, K valley 21
MLD, Agaram and Madivala 16 MLD and from earthen drain is 3 MLD
and 162 MLD treated water from K and C valley secondary treatment plant
is entering the lake. The total quantity of treated and untreated water
entering the Bellandur lake is about 224 MLD.
Objectives:
1. To study the characteristics of
Allasandra and Bellandur lake
water
2. To study the groundwater quality in the vicinity of the selected
lakes.
3. To study the characteristics of sediment with respect to heavy
metals of the selected lakes.
4. To study the spatial distribution of BOD by using MapInfo and
Surfer software.
Methodology
Five sampling points were selected at appropriate places for sample
collection of lake water in Allalasandra and Bellandur lakes. The location
of the points is as shown in Figure 1 and 2 respectively for Allalasandra
and Bellandure lakes . Several water quality parameters such as pH,
electrical conductivity, temperature, turbidity, dissolved oxygen, total
hardness, calcium hardness, magnesium hardness, potassium, BOD, iron,
copper, lead, cadmium, nickel, manganese, total chromium and zinc were
analysed for lake and ground water. Similarly lead, cadmium, nickel, total
chromium and zinc parameters were selected for sediment analysis. Three
sampling points for sediment analysis and two points for groundwater were
taken for analysis.
The samples were analysed as per the standards (standard methods for
the examination of water and wastewater 1998). The lake water data
collected was analysed by using Map Info and Surfer Software to know the
spatial distribution of pollutants in the lake water.
RESULTS AND ANALYSIS
The quality of the surface water of Allalasandra lake is shown in Table 1 and
that of Bellandur lake in Table 3. The concentration of heavy metals in the
sediments of Allalasandra and Bellandur are shown in the Table 2 and 4.
The groundwater quality in the vicinity of the selected lakes is shown in
Tables 2 and 4 respectively.
DISCUSSIONS.
Allalasandra lake
Concentration of some of the parameters like pH, electrical conductivity,
turbidity, chlorides, total hardness, calcium, magnesium, total dissolved
solids, sulphates, nitrates, and iron ranged between 7.4-7.6, 0.8-1.2, 0.6-30,
88-288, 257-244, 135-230, 60-198, 686-804,16-34, 0.4-0.8 and 0.24-1.3mg/l
respectively. When compared to drinking water standards, the concentration
exceeds the limits for most of the parameters.
With respect to few parameters namely pH, sulphates, nitrates, Cu,
Pb, Mn, Cr and Zn are with in the limits specified for drinking water. The
sodium absorption ratio
and percentage of sodium estimated for the
Allalasandra lake water was found to be good (BIS 1991) for irrigation.
The lake water can be used for irrigation as per FAO (1979) standards for
heavy metals.
The concentration of lead, cadmium, nickel, total chromium and zinc
in the sediment of Allalasandra lake was found to be 6.8, 0.1, 2.0, 7.2 and
20.2 mg/Kg respectively. Comparing it with the permissible limits as per
Csillag et. al., 1998 shows that the concentration are well within the limits.
The groundwater quality adjacent to Allalasandra lake is as shown in
Table 2. The concentration of some of the parameters such as pH, chlorides,
total hardness, calcium, magnesium, total dissolved solids, sulphates, iron
and manganese are exceeding the permissible limits of drinking water
standards (IS: 10500 – 1991). The concentration of heavy metals such as
copper, lead, cadmium, total chromium and zinc are within the permissible
limit.
The reason for the deterioration of groundwater quality may be due to the
continuous percolation of polluted surface water.
The spatial distribution of BOD in Allalasandra lake as shown in
Figure 1, depicts that at the inlet points the BOD is high (164mg/l) and it
goes on to decrease with increase in the distance towards the outlet point.
Compared to outlet point i.e. 3 and middle point 2 and 5 (i.e. at the left bank)
the BOD is less at 3. At point 5 (left bank) which is also located in the
middle portion of the lake, the concentration of BOD is comparatively high,
so the reason may be due to the inflow of wastewater just on the upstream
side of point 5 on the left bank. The decrease in the BOD of the lake water
during its retention in the lake may be due to the process of self purification
and the results shows that the decrease in the BOD is very significant.
BELLANDUR LAKE
Concentration of some of the parameters like pH, turbidity, chlorides,
total hardness, calcium, magnesium, total dissolved solids, sulphates,
nitrates, and iron ranged between 7.0-8.0, 12-35, 48-140,170-290,148-240,
22-116, 542-812, 12-35,0.25-7 and 0.2–0.4mg/L. The concentration of pH,
turbidity, calcium, magnesium, total dissolved solids, sulphates and iron are
exceeding the drinking water limits (IS: 10500 – 1991). With respect to a
few parameters namely chlorides, total hardness, nitrates are within the
limits specified for drinking water. Concentrations of heavy metals like
copper, lead, cadmium, manganese, total chromium and zinc are 0.013,
BDL, BDL, 0.178, 0.0015 and 0.5 mg/l respectively. When compared with
drinking water standards the concentration of manganese is exceeding the
limits. The sodium absorption ratio value and percentage sodium estimated
for the Bellandur lake water was found to be good (BIS 1991) for irrigation.
The lake water can be used for irrigation as per FAO (1979) standards for
heavy metal concentration.
The concentration of lead, cadmium, nickel, total chromium and zinc
in the sediment of Bellandur lake was found to be 23.03, 0.767, 65.5, 81.0
and 110 mg/kg. Comparing it with the permissible limits as per Csillag et.
al., 1998 it shows that the concentrations are not within the limits.
The ground water quality adjacent to Bellandur lake is as shown in
Table 4. The concentration of some of the parameters such as chlorides, total
hardness, calcium, magnesium, total dissolved solids, sulphates, nitrates,
manganese are exceeding the permissible limits of drinking water standards
(IS: 10500 – 1991).
The spatial distribution of BOD in Bellandur lake as shown in Figure 2,
depicts that at the inlet points the BOD is high (215 mg/l) and it goes on to
decrease towards the outlet . The decrease in the BOD of the lake water
during its stay in the lake may be due to the process of self-purification and
the results shows that the decrease in the BOD is very significant.
Conclusion
Allalasandra lake
The lake water quality is poor with respect to turbidity, chlorides, total
hardness, calcium, magnesium, total dissolved solids, iron and manganese,
which restricts its use for domestic purpose.
The sediment quality with respect to heavy metals is with in the permissible
limit to use it for agricultural applications.
The groundwater quality is poor with respect to
pH, chlorides, total
hardness, calcium, magnesium, total dissolved solids, sulphates, iron and
manganese to use it for drinking purpose.
The phosphate concentration is greater than 100 µg, therefore the lake water
can be categorised as eutrophic lakes.
The dissolved oxygen is below 4 ppm, therefore no aquatic life was found.
The decrease in BOD level from 164 to 6 mg/l with in the lake during its
movement from inlet to outlet showed, 96.34% reduction, therefore the lake
system has very good self purification potential.
The lake water is good for agricultural use as per SAR (Sodium Absorption
Ratio) for irrigation water quality classification.
The lake water can be used for irrigation as it satisfies FAO (1979) standards
for heavy metals namely Cd, Cr, Cu, Fe, Pb, Ni and Mn.
Bellandur lake
The lake water quality is poor with respect to
pH, turbidity, calcium,
magnesium, total dissolved solids, sulphates, iron and manganese, restricts
its use for domestic purpose.
The sediment quality with respect to heavy metals is not with in the limits
and it cannot be used for agricultural applications.
The ground water quality is poor with respect to chlorides, total hardness,
calcium, magnesium, total dissolved solids, sulphates, nitrates, lead and
manganese to use it for drinking purpose.
The phosphate concentration is greater than 100 µg, therefore the lakes can
be categorized as hypereutrophic lakes.
The dissolved oxygen is below 4 ppm, therefore no aquatic life was found.
The decrease in BOD level with in the lake during its movement from inlet
to outlet is 91.16% (from 215 to 19 mg/l) , therefore the system is very
significant in decreasing the BOD.
The lake water is good for agricultural use as per SAR (Sodium Absorption
Ratio) for irrigation water quality classification.
The lake water can be used for irrigation as it satisfies FAO (1979) standards
for heavy metals namely Cd, Cr, Cu, Fe, Pb, Ni and Mn.
References
(1) Proceedings of National Seminar on Resurrection of Lakes, 8th Jun-2002.
(2) Ramachandra T. V. and Ahalya N, Limgis2001, Monograph on
“Essentials in limnology and Geographic Information System (GIS)”
(3) International workshop on Integrated Water Management, Bangalore
University (June 2001).
(4) Arnold E. Greenberg, APHA, Chairman (1998), 20th Edition, “Standard
methods for the examination of water and waste water”.
(5) IS 3025: Methods of Sampling and Test (Physical and Chemical) for
Water and Wastewater.
(6) UNEP/WHO/UNESCO/WMO Programme on Global Water quality
monitoring and assessment gems/water operational guide, National Water
Research Institute, Canada.
(7) Erin Carison et. al., (2002) University of Northern Iowa, Department of
Mathematics, A Statistical Examination of Water Quality in Two Iowa
lakes; American Journal of Underground Water Research, Volume 1.
Table1: Allasandra Lake water quality
Parameters
Sample
Sample
Sample
Sample
1
2
3
4
Sample Rang
5
e
P.L.
(IS:10
500)
PHYSICAL
PARAMETERS
PH
7.4
7.5
7.4
7.6
7.5
7.4-
6.5-
7.6
Electrical
0.9
1.2
1
0.8
0.95
conductivity
Temperature
8.5
0.81.2
25 C
25
25.4
23.7
24.2
23.725.4
Turbidity
30
21.4
10.8
0.6
7.5
0.6-
10
30
CHEMICAL
PARAMETERS
Dissolved
1.0
1.0
2.6
1.7
1.02
oxygen
Total alkalinity
112.6
280
266
251
238
258
230280
Chlorides
150
288
88
176
144
88-
250
288
Total hardness
257
315
333
311
344
257-
300
344
Calcium
197
230
135
210
204
135-
75
230
Magnesium
60
102
198
101
140
60198
Sodium
110
101
100
120
98
98-
30
120
Total
dissolved
740
804
710
686
686-
738
solids
500
804
Sulphates
34
31
31
16
33
16-34
150
Nitrates
0.8
0.8
0.4
0.63
0.42
0.4-
45
0.8
Phosphates
0.6
0.5
0.3
0.4
0.3-
0.62
0.62
Potassium
42
45
34
42
34
34-45
BOD
164
38
06
06
44
6-164
Table2:Allalasandra Ground Water Quality
Physical
Sample 1
Sample 2
parameters
P.L.
(IS:10500)
PH
6.6
6.2
Electrical
1.3
1.5
Total alkalinity
266
242
Chlorides
419
323
250
Total hardness
379
214
300
6.5-8.5
conductivity
CHEMICAL
PARAMETERS
Calcium
347
168
75
Magnesium
32
46
30
Sodium
130
164
1080
1140
500
Sulphates
82
168
150
Nitrates
2.2
7.36
45
Phosphates
0.01
0.02
Potassium
10
16
Total
dissolved
solids
Table3:Heavy metal concentration in lake water, sediment and
groundwater.
Heavy
Lake
Ground
P.L.
metals
water
water
(IS:10500)
Sedimen Standards
t of lake
bed
for
agricultural
soils
Copper
0.013
0.018
0.05
37.4
Lead
0.001
0.03
0.1
6.8
8.33
Cadmium
0.005
0.001
0.05
0.1
0.125
Nickel
0.08
0.075
-
20
1.67
Manganese
0.178
0.82
0.1
54
Total
0.0015
0.024
0.05
7.2
8.33
0.001
0.04
5.0
20.2
25
chromium
Zinc
Table4:Bellandur lake water quality
Parameters
S1
S2
S3
S4
S5
Range
P.L.
(IS:105
00)
PHYSICAL
PARAMETERS
PH
7.5
7.0
8.0
7.6
7.0
7.0-8.0
Electrical
1.2
1.1
0.946
1.1
1.0
1-0.946
24.2
30
29.2
31
290
24.2-31
35
31
12
30
31
12-35
Dissolved oxygen
0.3
1.4
3.0
6
0.5
0.3-6
Total alkalinity
584
284
330
530
560
284-
6.5-8.5
conductivity
Temperature
Turbidity
10.0
CHEMICAL
ARAMETERS
560
Chlorides
140
124
115
48
130
48-140
250
Total hardness
286
254
170
290
280
290-
300
170
Calcium
170
209
148
240
230
148-
75
240
Magnesium
116
45
22
50
50
22-116
Sodium
90
100
70
98
110
70-110
Totaldissolved
812
750
542
780
640
542-
solids
Sulphates
30
500
812
16
18
20
12
35
12-35
150
Nitrates
0.36
0.4
0.25
0.8
7
0.25-7
45
Phosphates
0.85
0.3
0.4
0.6
0.95
0.30.95
Potassium
42
34
38
35
30
30-42
BOD
215
19
10
20
50
19-215
Table5:Bellandur Ground water quality
Physical parameters
Sample 1
Sample
P.L.
2
(IS:10500)
6.5-8.5
PH
6.3
6.2
Electrical
2.6
2.2
conductivity
CHEMICAL
PARAMETERS
Total alkalinity
144
192
Chlorides
907
640
250
Total hardness
339
610
300
Calcium
286
590
75
Magnesium
53
20
30
Sodium
86
220
3254
2080
500
Sulphates
176
110
150
Nitrates
27.2
65.4
45
Phosphates
0.06
0.04
Potassium
18
22
Total
dissolved
solids
Table6:Heavy metal concentration in lake water, sediment and
groundwater.
Heavy
Lake
Ground
P.L.
Sediment
metals
water
water
(IS:10500)
of lake
bed
Standard
Copper
0.013
0.018
0.05
64.96
Lead
BDL
3.7
0.1
23.03
8.33
Cadmium
BDL
0
0.05
0.767
0.125
Nickel
0.08
0.075
65.5
1.67
Manganese
0.178
0.82
0.1
211.3
Total
0.0015
0.024
0.05
81.0
8.33
0.5
0.52
5.0
110
25
chromium
Zinc