urban groundwater quality and quantity in sub- · daniel cw nkhuwa (phd) school of mines,...

Daniel CW Nkhuwa (PhD)

School of Mines, UNZA, Lusaka

[email protected]

Urban Groundwater Quality and Quantity in Sub-

Saharan Africa: A Case for Lusaka, Zambia

International Conference on Geology, Mining, Mineral and Groundwater Resources of the

Sub-Saharan Africa: Opportunities and Challenges Ahead, Livingstone, Zambia, 11 – 13

July 2017

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1. Introduction

All water – contained in Hydrologic Cycle, which:

describes movement & interrelationships among surface water,

groundwater, and water in atmosphere.

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1. Introduction…..contd.

So

urc

e:

Tasa D

, Tarb

uck E

J, &

Lutg

ens F

K (

1997)

Accordingly, most of freshwater is stored underground.

Water plays very essential role in every person's life. In terms of

distribution,:

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Groundwater:

contributes significantly to stream-flow in humid regions.

So

urc

e:

Tasa D

, Tarb

uck E

J, &

Lutg

ens F

K (

1997)


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…..it is a HIDDEN resource

But Groundwater is a unique resource……

So

urc

e:

AG

W-N

et T

rain

ing

Ma

nu

al (2

01

3)

Surface water – easier to deal with…..……


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Source: Lapworth (2014)

Africa has huge potential for

groundwater, but which is threatened,

among others, by:

Over abstraction, and

Quality impairment

2. State of Continent’s Water Resources

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Among factors that have affected state of water

resources include a Rapidly Growing Population.

Population Growth and Water

Availability in the SADC region

Glo

ba

l W

orl

d P

op

ula

tio

n G

row

th

so

urc

e:

Parida &

Kenabath

o (

2012)

2. State of Continent’s Water Resources…..contd.

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Consequence(s) of rapid growth in population:

expansions in economies, resulting in;

Increased demand for water, while

availability might remain constant or even dwindle, causing

demand to outstrip Supply.

Degradation in Water quality and, quantity thereby

Inciting water-use conflicts.

2. State of Continent’s Water Resources…..contd.

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2

4

6

8

10

12

14

19

60

19

65

1970

19

75

19

80

19

85

19

90

1995

20

00

20

05

20

10

Popu

latio

n (

10

6)

Growth of Population in Lusaka(1964 – 2010)

Growth of Population in Zambia(1963 – 2010)

Major one has mainly been a rapidly growing population.

196

536

769

1,200

2,100

0

500

1,000

1,500

2,000

2,500

1964 1980 1990 2000 2010T

housands

3. Factors affecting state of (Ground)Water Resources in Zambia

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1928 1951 1965

1975 1981 2002

3. Factors affecting state of (Ground)Water Resources in Zambia…..(2)

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With population = 2.1 million, &

420,000 m3 d-1

Water supply scenario in Lusaka as at 2010:

0.1

96 0

.536

0.7

69

1.2

2.1

0

0.5

1

1.5

2

2.5

1964 1980 1990 2000 2010

Popula

tion (

x10

6) Assuming 200 litres per

capita per day….

Official supply ca. 240,000 m3 d-1

Deficit

ca. 180,000 m3 d-1

Data Source: Lusaka Water & Sewerage company (LWSC) and Central Statistical Office (CSO)

3.1 Groundwater Over-abstraction

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391.07

143.00

99.67

73.00

41.71 0

50

100

150

200

250

300

350

400

450

0

5

10

15

20

25

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

An

nu

al P

er

ca

pita

Wa

ter

Ava

ilab

le (

m3)

Po

pu

lation

x 1

000

00

Population

Annual Per capita water available (m3)

Population Growth vs. Per capita annual available water

Data Source: Lusaka Water & Sewerage company (LWSC) and Central Statistical Office (CSO)

114 l c-1 d-1

1,072 l c-1 d-1

This per capita consumption

is exacerbated by leaks in

conveyance system of about

45%.

3.1 Groundwater Over-abstraction…..(2)

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Fluctuation of grdwater table in some LWSC bhs (87 – 96)

Partial spread of private and public boreholes in Lusaka

Data Source: Lusaka Water & Sewerage company (LWSC) and Department of Water Affairs

3.1 Groundwater Over-abstraction…..(3)

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Waterborne

25% Pit latrines

55%

Septic tanks

20%

Distribution of excreta / wastewater disposal systems in Lusaka

3.3 Wastewater / Excreta Disposal Systems…..contd.

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Proximity of pit latrines to water points….

i) In High-density settlements

…and implications of flooding on groundwater

quality.


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Water points and On-

site sanitation systems

in a high-density

settlement with pit

latrines (RED) and

shallow wells (BLUE)

i) High-density settlements


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Septic tank

House

Borehole

Tenant #8

Tenant #6

Tenant #4

Tenant #5

Tenant #9

Tenant #7

Tenant #2

Tenant #3

Tenant #1


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ii) Low Density Settlements

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Water points and On-site

sanitation systems in a low-

density settlement

septic tanks (RED) & boreholes

(BLUE)

Built on a karstified terrain:


ii) Low-density settlements

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Water quality from shallow wells in a high-density settlement of Lusaka (dry

seasons 2003 & 2004; wet seasons 2004 & 2005)

3.3 Quality of Groundwater

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a) Shallow Wells (High Density Settlements)

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0

5

10

15

20

25

30

SP

01

SP

03

SP

05

SP

07

SP

09

SP

11

SP

13

SP

15

SP

17

SP

19

SP

02

SP

04

SP

06

SP

08

SP

10

SP

12

SP

14

SP

16

SP

18

SP

20

NO

3-C

on

ce

ntr

atio

ns (

mg

mg

l-1

)

Dry Season Wet Season

45

.5

4.5

4

1.4

8.7

5.8

4.5

1.5

0

5

10

15

20

25

30

35

40

45

50

0

50

100

150

200

250

300

350

1.4

.13

2.4

.13

3.4

.13

4.4

.13

5.4

.13

6.4

.13

7.4

.13

8.4

.13

9.4

.13

10

.4.1

3

11

.4.1

3

12

.4.1

3

13

.4.1

3

14

.4.1

3

15

.4.1

3

16

.4.1

3

17

.4.1

3

18

.4.1

3

19

.4.1

3

20

.4.1

3

Daily R

ain

fall (

mm

)

Colifo

rm c

oun

ts (

#/1

00 m

l)

Dates of the month of April 2013

TC (#/100ml)

FC (#/100ml)

E-Coli (#/100)

Rainfall

TNTC TNTC

Sampling Dates

Coliform loading (Rainy Season 2013)

Nitrate and coliform loading Dry Season

2012 & Wet Season 2013

Borehole water quality from a low-density settlement of Lusaka

3.3 Quality of Groundwater…..contd.

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b) Boreholes (Low Density Settlement)

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0

20

40

60

80

100

120

140

160

180

200K

1

K3

K5

K7

K9

K1

2

K1

4

K1

8

K2

1

K2

3

K2

7

K3

9

K4

2

K1

5

K2

0

K2

5

K3

0

K3

2

K3

4

K3

6

K3

8

K4

3

K4

5

K4

7

K4

9

Nit

rate

(m

g/L

)

Wet Dry Nitrate

Wells Boreholes

WQ standard

3.3 Quality of Groundwater…..contd.

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c) Boreholes & Shallow Wells (Low- & High-Density Settlements)

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Consumption of poor quality water has

usually resulted in:

Outbreaks of waterborne diseases

(cholera, typhoid, etc.).

Consequence;

Expenditure of vast unbudgeted-

for resources (time, money, etc.) on

health care services, which

resources could’ve been directed

to other sectors of development.

Loss of productive time due to

illnesses that are otherwise

avoidable.

Cholera centre established during such

outbreaks in Lusaka

4. Impact of Groundwater Quality on Disease Burden

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Weekly Historical trends of cholera cases in Lusaka (2003/04 – 2009/10)

So

urc

e:

NE

PP

CM

C R

eport

s, M

in o

f H

ealth

4. Impact of Groundwater Quality on Disease Burden…..contd.

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So

urc

e:

NE

PP

CM

C R

ep

ort

s,

Min

. o

f H

ea

lth

Historical cholera and rainfall data for Lusaka (2003/04 – 2009/10)

4. Impact of Groundwater Quality on Disease Burden…..contd.

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The foregoing indicate the need to re-think city’s development in order to:

Reconcile any conflicting requirements for different land uses, that would

ensure;

sustainable use of available groundwater resources

a safe, healthy, useable, serviceable & pleasant environment for all

a protected natural environment, in which people can live a healthy

and productive life – now and in the future.

5. Concluding Remarks.

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In this regard, country needs to:

Adequately fund and coordinate research for early warning of

impending outbreaks.

Create platforms for sharing and disseminating research results.

Develop a culture of using research results to inform decision-

making processes in different sectors of development.

Sync. between urban development & groundwater resources’

development and management.

Training for a cadre of adequately skilled water sector and

development planning professionals at all levels.

5. Recommendations

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urban groundwater quality and quantity in sub- · daniel cw nkhuwa (phd) school of mines,...

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