UPGro – Africa Groundwater Research

Rainwater Harvesting

Water Point Mapping

RWSN 2014 Webinars

(Sept – Dec)

A series of webinars in English and in

English/French

23rd September – 9th December 2014

Register on: http://tinyurl.com/RWSN2014

Webinar 9 – Groundwater Research 25th November 2014

Groundwater Quality

• Groundwater safe-sourcing and fluoride mitigation, Oromia, Ethiopian Rift Valley - Pauline Smedley

• Domestic groundwater safety in Kisumu, Kenya: past, present and future – Jim Wright

• Discussant – Robert Hope

DOMESTIC GROUNDWATER

SAFETY IN KISUMU, KENYA:

PAST, PRESENT AND FUTURE

Dr. Jim Wright (University of Southampton)

On behalf of:

Joseph Okotto-Okotto (Victoria Institute for Research on Environment & Development International)

Dr. Lorna Grace Okotto (Jaramogi Oginga Odinga University of Science & Technology)

Dr. Heather Price (University of Southampton)

Dr. Steve Pedley (University of Surrey)

3

background

• Urban population increase to 1.2 billion by 2050 in sub-

Saharan Africa

• Piped utility water coverage lags behind growth

• Groundwater used in informal settlements to supplement

piped water

• Contamination risks, e.g. from onsite sanitation

• Effect on surrounding rural areas, small towns?

• How does urban growth affect groundwater safety and

quality?

4

Objectives & study site

• Objectives

• How have groundwater contamination risks changed in response to

urbanisation?

• How has water quality changed in response to urbanisation?

• What might urban groundwater use look like by 2030?

• Case study sites:

• Kisumu, Kenya (population of 259,258 in 2009)

• Manyatta A and Migosi informal settlements

• >39% and >24% of households using hand-dug wells in 2009

• 95% and 67% onsite sanitation in 2009

5

Methods: past groundwater safety

• Historic projects • VIRED International

• University of Surrey

• 1999: Map of wells, buildings & sanitation

• 2002-04: sanitary risk inspection & water quality testing of 51 sample wells, e.g. • Thermotolerant coliforms

• Nitrate

• Chloride

• Electro-conductivity

6

Methods: present groundwater safety

• Transect survey

• 0.1 x 2.4km & 0.1x

1.7km random transects

• Record wells, pit latrines

• Buildings map:

• Satellite imagery

interpretation

• sample survey of wells

• Sanitary risk inspection

• Water quality testing

7

Methods: future groundwater safety

• Expert panel, July 2014

• Presentations, e.g.

• Current situation

• Water utility

• International Futures

software

• Mapping 2030 patterns :

• Sanitation access

• Domestic water access

• Population density

• 3 groups

8

Results: changes in built environment Building density, 1999 Building density, 2013

9

Results: changes in built environment

2004 2013

10

Results: changes in built environment

2004 2013

11

Results: changes in built environment

Transect survey: hand-dug wells Transect survey: pit latrines

12

0

5

10

15

20

25

30

35

40

45

50

1999 and2014

1999 only 2014 only

No

. o

f w

ell

s

Migosi

Manyatta A

0

50

100

150

200

250

1999 and2014

1999 only 2014 only

No

. o

f p

it l

atr

ine

s

Migosi

Manyatta A

Results: changes in built environment

• Significant increase in risk [Wilcoxon signed-rank test p =

.048, z = 1.98]

13

2014 2002-04

Results: groundwater quality changes

14

Wilcoxon signed-rank

test, z = -3.296, p = .001

Wilcoxon signed-rank

test, z = -1.7, p = .097

2014 2004

2014 2002-04

Results: groundwater quality changes

Predictor of nitrate Coefficient standard error T statistic P>t

Sanitary risk % 0.11 0.05 2.17 0.04

Mean daily rainfall on

day & preceding 3

days(mm)

1.41

0.36 3.95

0.00

Baseline measurement

– both sites (binary) -12.80

4.11 -3.12 0.00

Baseline measurement

from Manyatta (binary) 29.87

3.20 9.33 0.00

Constant -5.60 4.17 -1.34 0.18

• Linear regression predicting nitrate as N (n=58; adjusted R2 = 0.78) – 2004 and 2014

• More nuanced picture after accounting for rainfall

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Results: future domestic water use

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Discussion:

• Changes from 1999 to 2014:

• Groundwater use remained significant alongside onsite sanitation

• Contamination risks have intensified

• Contradictory water quality results – rainfall?

• Changes from 2014 to 2030:

• Domestic urban groundwater use continues as part of supply mix

• More certainty about future of high income areas

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Conclusions & Implications

• Urban growth and groundwater safety:

• Exacerbated contamination risk in established urban

neighbourhoods

• Effects more pronounced in small towns, peri-urban areas?

• Where are areas with groundwater for domestic use:

• Vulnerable to contamination now?

• Vulnerable to contamination by 2030?

• Approaches for managing urban safety:

• Adapt sanitary risk form for expanding urban areas?

• More evidence on source protection

• Regulation and governance, e.g. vended groundwater

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RWSN’s Groundwater Community: https://dgroups.org/RWSN/groundwater