7.1General
Water quality is generally determined by solutes and gases dissolved in the water as well as the matter suspended in and floating on it (Fetter, 1994). In this regard, water quality is a consequence of the natural physical and chemical state of the water as well as any alterations that may occur as a result of human activity. The usefulness of water for a particular purpose is determined by its quality. If human activity alters the natural water quality so that it is no longer fit for use for which it was initially suited, the water is said to be polluted or contaminated.
7.2water quality
The term Water quality is used to describe the microbiological, physical and chemical properties of water that determine its fitness for use. Many of these properties are controlled or influenced by substances, which are either dissolved or suspended in water. Therefore, water pollution occurs when water is rendered less fit for use as a result of human activities such as dense human settlements, particularly those with poor sanitation facilities.
Water quality affects the domestic user in terms of:
-
Health
-
Aesthetics – the appearance of the water or effects it has on clothes and household fixtures such as baths, and
-
Economics – replacement of pipes, hot water geysers, etc.
Health effects of water quality on the domestic user include:
-
Acute effects – ones that can be seen after a very short time.
-
Chronic effects – those that show only after the water has been used for a long time.
7.2.1Sampling Campaigns
Three sampling campaigns were planned for this project – the first at the end of dry/start of rainy season, the subsequent ones being in the middle and end of the rainy season.
The first sampling campaign was undertaken in mid-November, just before the onset of the rainy season. The other campaigns have been planned for mid-February – during the rainy season – and mid-April (towards the end of the rainy season), respectively, in order to compare the variability of pollutants with varying levels of saturation in the aquifer.
The following parameters were identified for analysis in the first sampling campaign - pH, conductivity, chloride, fluoride, sulphate, nitrite and nitrate, total coliforms and faecal coliforms. The selection of these parameters was because they portray information on the potability of the water as shown in Table 9.
Table 9: Water quality substances of key relevance for domestic use
KEY SUBSTANCES
|
RELEVANCE TO DOMESTIC USERS
|
Microbiological quality
|
Faecal coliforms
|
Indicates recent faecal pollution and the potential risk of contracting infectious diseases
|
Total Coliforms
|
Indicates the general hygienic quality of the water
|
|
Physical quality
|
Conductivity / Total Dissolved Salts
|
Affects the taste and 'freshness' of the water
|
pH
|
Affects the taste and corrosivity of the water
|
|
Chemical quality
|
Chloride
|
May impart a salty taste to the water
|
Nitrate and nitrite
|
May be toxic to infants
|
Sulphate
|
Excessive amounts cause diarrhoea
| 7.2.2Analytical Results
Results of the first sampling campaign as are shown in Table 10 below. The water points from which the samples where collected are shown in Fig. 29.
The most important water quality problem in the project areas of John Laing and Misisi is that of faecal pollution together with the associated disease-causing organisms. In addition, conductivity, which is indicative of elevated salt concentrations (TDS, Sulphate and Chloride) are common.
Faecal pollution
High faecal and total coliform counts (used as indicator organisms for recent faecal pollution) occur in most water points in the settlement.
Conductivity (TDS)
Water sources in the settlements, particularly John Laing, have high values of conductivity (and thus TDS) which appears to result mostly from high chloride, nitrate and sulphate concentrations. A plot of conductivity against concentration of other parameters – Chloride, Sulphate, Nitrate and Phosphate – indicates linear correlations between conductivity and the four quality variables considered (Fig. 30).
Sulphate and Chloride
Water with high conductivity (high TDS) also tends to have high sulphate and chloride concentrations as indicated in these analyses. Sulphate removal is expensive (desalination or ion exchange) and normally not considered viable.
Table 10: Results of the first sampling campaign in the project areas of Lusaka, November 2003
1 JOHN LAING
|
GPS INFORMATION
|
PHYSICAL CHEMICAL RESULTS
|
MICROBILOGICAL RESULTS
|
|
Eastings
|
Northings
|
pH
|
Conductivity (S/cm)
|
Chlorides (mg/l)
|
Nitrate (as NO3-N mg/l)
|
Nitrite (as NO2-N mg/l)
|
Ammonia (as NH4-N mg/l)
|
Sulphate (mg/l)
|
Total Phosphates (mg/l)
|
TC (No/100ml)
|
FC (No/100ml)
|
Locality
|
636010
|
8292405
|
7
|
1236
|
7
|
10.2
|
0.84
|
0.3
|
55.6
|
2.89
|
26
|
6
|
Islamic Borehole - 4
|
636089
|
8292396
|
7.2
|
1345
|
174
|
10.8
|
0.37
|
0.18
|
49.5
|
2.79
|
TNTC
|
TNTC
|
Shallow well
|
635664
|
8292298
|
7.3
|
1401
|
79
|
3.8
|
0.068
|
0.09
|
28.4
|
2.99
|
12
|
5
|
Islamic Borehole -2
|
|
|
7.3
|
1400
|
81
|
3.82
|
0.066
|
0.09
|
28.2
|
3.09
|
10
|
4
|
Islamic Borehole -2 Duplicate
|
635673
|
8292371
|
7.3
|
1446
|
6
|
11.6
|
1.058
|
0.28
|
30.9
|
3.01
|
TNTC
|
TNTC
|
Shallow well near islamic borehole - 2
|
635847
|
8292190
|
8.1
|
1063
|
80
|
16.1
|
2.625
|
1.78
|
28
|
4.98
|
TNTC
|
TNTC
|
Shallow well in depression
|
635613
|
8292121
|
8.2
|
1177
|
81
|
18.8
|
0.873
|
0.1
|
27.5
|
5.38
|
120
|
66
|
Mutenje Bar
|
635526
|
8292177
|
7.2
|
1408
|
100
|
24.9
|
0.868
|
2.59
|
35.9
|
5.55
|
TNTC
|
TNTC
|
Near Dollose
|
635407
|
8292002
|
8.1
|
1044
|
70
|
19.3
|
0.554
|
1.91
|
17.4
|
4
|
TNTC
|
TNTC
|
Near Tafimbwa Lubilo School
|
635339
|
8291745
|
8.2
|
765
|
39
|
11.8
|
0.265
|
<0.01
|
11.5
|
4.07
|
TNTC
|
TNTC
|
Near Chanda Bar
|
635190
|
8291700
|
8.4
|
652
|
44
|
10.8
|
0.69
|
<0.01
|
5.8
|
3.48
|
400
|
160
|
Yellow House
|
635076
|
8292133
|
8.2
|
1371
|
110
|
18.1
|
1.46
|
3.88
|
26.6
|
4.13
|
TNTC
|
TNTC
|
Kapumuleni Mini Mart
|
634984
|
8292328
|
7.2
|
1120
|
77
|
16.3
|
0.23
|
0.15
|
57.5
|
5.49
|
0
|
0
|
Salvation Army BH
|
|
|
7.2
|
1107
|
79
|
16.8
|
0.28
|
0.19
|
54.2
|
6.13
|
0
|
0
|
Salvation Army BH1 (Duplicate)
|
635318
|
8292417
|
8.2
|
1489
|
125
|
23.6
|
1.344
|
1.95
|
34.9
|
4.54
|
250
|
47
|
Near Twiza
|
635344
|
8292368
|
8.2
|
1962
|
149
|
20
|
2.804
|
4.08
|
45.4
|
4.52
|
300
|
122
|
Near Twiza 2
|
635384
|
8292302
|
8.5
|
1686
|
144
|
18.3
|
0.32
|
2.12
|
33.9
|
4.25
|
0
|
0
|
Near Twiza 3
|
635512
|
8292435
|
8.1
|
1228
|
84
|
17.3
|
0.314
|
0.35
|
38.3
|
6.03
|
TNTC
|
TNTC
|
Near Salvation Army, with reeds
|
-
|
-
|
8.1
|
1225
|
80
|
17.8
|
0.173
|
0.37
|
37.8
|
5.91
|
0
|
0
|
Salvation Army Bolehole 2
|
635732
|
8291942
|
7.4
|
679
|
44
|
-
|
0.019
|
0.03
|
-
|
-
|
0
|
0
|
Political borehole
|
|
|
7.3
|
676
|
49
|
35.2
|
0.019
|
0.02
|
4
|
1.21
|
0
|
0
|
Political borehole (Duplicate)
|
Table 10 (continued): Results of the first sampling campaign in the project areas of Lusaka, November 2003
Eastings
|
Northings
|
pH
|
Conductivity (µS/cm)
|
Chlorides (mg/l)
|
Nitrate (as NO3-N mg/l)
|
Nitrite (as NO2-N mg/l)
|
Ammonia (as NH4-N mg/l)
|
Sulphate (mg/l)
|
Total Phosphates (mg/l)
|
TC (No/100ml)
|
FC (No/100ml)
|
Locality
|
635247
|
8292244
|
7.1
|
1413
|
157
|
38.8
|
1.677
|
6.13
|
9
|
1.78
|
TNTC
|
TNTC
|
Near new saloon and barbershop
|
635274
|
8292607
|
6.8
|
1043
|
92
|
38.8
|
0.579
|
0.44
|
19
|
1.67
|
TNTC
|
TNTC
|
In caverns
|
635476
|
8292545
|
6.9
|
1032
|
92
|
36.9
|
0.532
|
1.62
|
39
|
1.79
|
150
|
30
|
|
635585
|
8292563
|
6.9
|
1035
|
92
|
35.1
|
0.599
|
1.66
|
37
|
1.96
|
TNTC
|
TNTC
|
|
635660
|
8292592
|
7.2
|
1056
|
103
|
39.53
|
0.541
|
0.47
|
18
|
1.67
|
TNTC
|
TNTC
|
Bambe Grocery
|
635746
|
8292608
|
6.9
|
1187
|
106
|
34.5
|
0.528
|
3.32
|
58
|
1.48
|
170
|
90
|
|
2 MISISI COMPOUND
|
637216
|
8293553
|
6.2
|
610
|
28
|
15.5
|
2.24
|
0.71
|
42.5
|
1.05
|
TNTC
|
TNTC
|
Chairman's place
|
|
|
6.6
|
574
|
23
|
18.8
|
1.83
|
0.84
|
39.3
|
0.95
|
TNTC
|
TNTC
|
Chairman's place (Duplicate)
|
637230
|
8293043
|
6.7
|
771
|
45
|
16.5
|
0.4
|
1.08
|
60.1
|
1.04
|
26
|
5
|
Mississi Bole hole
|
637125
|
8293209
|
6.8
|
1340
|
107
|
15.4
|
0.8
|
3.96
|
74.6
|
1.52
|
TNTC
|
TNTC
|
Mr. Mwiinga's well
|
3 MASS MEDIA
|
642286
|
8296393
|
6.9
|
679
|
20
|
7.6
|
<0.001
|
0.03
|
21
|
1.56
|
20
|
3
|
From Tank; mass media
|
642971
|
8296316
|
6.6
|
711
|
25
|
11.5
|
<0.001
|
0.05
|
52.7
|
0.83
|
0
|
0
|
Near kalingalinga Bus stop
|
641630
|
8296640
|
6.6
|
676
|
19
|
7.9
|
<0.001
|
0.01
|
20.2
|
1.54
|
0
|
0
|
International School
|
641455
|
8296624
|
6.6
|
632
|
20
|
7.5
|
<0.001
|
<0.01
|
20.4
|
1.5
|
0
|
0
|
International School C
|
641864
|
8296794
|
6.6
|
690
|
18
|
7.8
|
<0.001
|
<0.01
|
23.2
|
1.85
|
0
|
0
|
International School 6E
|
642340
|
8296271
|
6.5
|
683
|
18
|
8
|
<0.001
|
0.01
|
25.3
|
2.12
|
0
|
0
|
Mass Media 3
|
Fig. 29: Location of water points sampled during the first campaign
Fig. 30: A regression plot to show the relationship of conductivity to chloride, nitrate, sulphate and phosphates in the Lusaka project areas.
7.3Safety of water for domestic use
Decision making on the suitability of water for domestic use is largely determined by the health problems related to drinking the water.
Records of cholera outbreaks in Lusaka, in general, and the project areas, in particular have already indicated an upswing since it broke out at the start of November – just before the onset of the rainy season. As at 30 January 2004, 2,482 cases of cholera had been reported for Lusaka alone with 110 deaths (see Box 1).
7.4Sensitisation, educational and awareness programmes
This study will be used to establish the type, extent, and vulnerability to pollution of the aquifer to pollution in the project areas and the possible link between consumption of this contaminated water with the occurrence of certain ailments/outbreaks.
Therefore, with data acquired from this research, a bulletin will be issued to the Ministry of Health and other concerned institutions to enable them formulate short- to medium-term community-based sensitisation and educational awareness campaign programmes on the connections between the state of the aquifer and health status of the city’s citizens.
8REFERENCES AND BIBLIOGRAPHIES
Central Statistical Office. 1990: 1990 Census of population, Housing and Agriculture – Preliminary report, 17pp, Lusaka.
Drysdall, A.R. (1960): The Geology of Lusaka. Rec.Geol.Surv.Northern Rhodesia, pp6-25
Lusaka City Council (LCC) & Environmental Council of Zambia (ECZ), 1997: Solid waste management master plan project for the city of Lusaka. Phase 1 – Diagnosis Final Report
Fetter, C.W. (1994): Applied Hydrogeology. 3rd Edition. MacMillan College Publishing Company. NewYork; Maxwell MacMillan Canada, Maxwell MacMillan International New York-Oxford-Singapore-Sydney.
Gibb Eastern Africa (1999): Final Report on Hydrogeological Investigations and Borehole inspections, Rehabilitation and test pumping. North-West Lusaka Water Project
GRZ/Ministry of Health (1991): National Health Policies and Strategies (Health Reforms). Planning Unit.
Headworth, H.G. (1983): The influence of urban development on groundwater quality. In; Groundwater in Water Resources Planning, vol.1, pp233-243, Koblenz, FRG.
Nkhuwa, D.C.W. 1996: Hydrogeological and Engineering Geological problems of urban development over karstified marble in Lusaka. Mitt.Ing. –u. Hydrogeol., Heft 63, 251S, Aachen
Nkhuwa, D.C.W. 1997: Waste disposal practices and the state of environmental health in Lusaka. Paper presented at the National Conference on Science and Technology on ‘The Role of Science and Technology in socio-economic development in Zambia’, 26-30 August 1997, Lake Kariba Inns, Siavonga.
Thornthwaite, C.W. & Matther, J.R. (1955): The water balance. Inst. Technology, Publ.Climate, 8, No.1, pp1-86
Ubell, K. (1961): Groundwater recharge by direct infiltration of rainfall. Int.Ass.Scien.Hydrol., Publ. 57, 586-596, Gentbrugge
Veihmeyer, F.J. (1964): Evapotranspiration. In Chow, Ven Te (Ed.); Handbook of applied Hydrology - a compendium of water-resources Technology. McGraw-Hill Book Company New York, San Francisco, Toronto. London.
Von Hoyer, M., Köhler, G. & Schmidt, G. (1978): Groundwater and Management Studies for Lusaka. Water Supply. Part 1, Groundwater Study. Hannover; B.G.R., 5 volms.
|