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

1

Sample

2

Sample

3

Sample

4

Sample

5

Rang

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 8.5

Electrical

conductivity

0.9 1.2 1 0.8 0.95 0.8-

1.2

Temperature 25 C 25 25.4 23.7 24.2 23.7-

25.4

Turbidity 30 21.4 10.8 0.6 7.5 0.6-

30

10

CHEMICAL

PARAMETERS

Dissolved

oxygen

1.0 1.0 2.6 1.7 1.02 11-

2.6

Total alkalinity 280 266 251 238 258 230-

280

Chlorides 150 288 88 176 144 88-

288

250

Total hardness 257 315 333 311 344 257-

344

300

Calcium 197 230 135 210 204 135-

230

75

Magnesium 60 102 198 101 140 60-

198

30

Sodium 110 101 100 120 98 98-

120

Total dissolved

solids

740 804 710 686 738 686-

804

500

Sulphates 34 31 31 16 33 16-34 150

Nitrates 0.8 0.8 0.4 0.63 0.42 0.4-

0.8

45

Phosphates 0.6 0.5 0.3 0.4 0.62 0.3-

0.62

Potassium 42 45 34 42 34 34-45

BOD 164 38 06 06 44 6-164

Table2:Allalasandra Ground Water Quality

Physical

parameters

Sample 1 Sample 2 P.L.

(IS:10500)

PH 6.6 6.2 6.5-8.5

Electrical

conductivity

1.3 1.5

CHEMICAL

PARAMETERS

Total alkalinity 266 242

Chlorides 419 323 250

Total hardness 379 214 300

Calcium 347 168 75

Magnesium 32 46 30

Sodium 130 164

Total dissolved

solids

1080 1140 500

Sulphates 82 168 150

Nitrates 2.2 7.36 45

Phosphates 0.01 0.02

Potassium 10 16

Table3:Heavy metal concentration in lake water, sediment and groundwater.

Heavy

metals

Lake

water

Ground

water

P.L.

(IS:10500)

Sedimen

t of lake

bed

Standards

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

chromium

Zinc 0.001 0.04 5.0 20.2 25

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 6.5-8.5

Electrical

conductivity

1.2 1.1 0.946 1.1 1.0 1-0.946

Temperature 24.2 30 29.2 31 290 24.2-31

Turbidity 35 31 12 30 31 12-35 10.0

CHEMICAL

ARAMETERS

Dissolved oxygen 0.3 1.4 3.0 6 0.5 0.3-6

Total alkalinity 584 284 330 530 560 284-

560

Chlorides 140 124 115 48 130 48-140 250

Total hardness 286 254 170 290 280 290-

170

300

Calcium 170 209 148 240 230 148-

240

75

Magnesium 116 45 22 50 50 22-116 30

Sodium 90 100 70 98 110 70-110

Totaldissolved

solids

812 750 542 780 640 542-

812

500

Sulphates 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 0.3-

0.95

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

2

P.L.

(IS:10500)

PH 6.3 6.2 6.5-8.5

Electrical

conductivity

2.6 2.2

CHEMICAL

PARAMETERS

Total alkalinity 144 192

Chlorides 907 640 250Total hardness 339 610 300

Calcium 286 590 75

Magnesium 53 20 30

Sodium 86 220

Total dissolved

solids

3254 2080 500

Sulphates 176 110 150

Nitrates 27.2 65.4 45

Phosphates 0.06 0.04

Potassium 18 22

Table6:Heavy metal concentration in lake water, sediment and groundwater.

Heavy

metals

Lake

water

Ground

water

P.L.

(IS:10500)

Sediment

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

chromium

0.0015 0.024 0.05 81.0 8.33

Zinc 0.5 0.52 5.0 110 25