The use of garden boreholes in Cape Town, South Africa: Lessons learnt from Perth, Western Australia

Article (PDF Available)inPhysics and Chemistry of the Earth Parts A/B/C 27(11-22):961-967 · December 2002with 3,146 Reads 
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
DOI: 10.1016/S1474-7065(02)00099-2
Cite this publication
Abstract
The similarities in climate and geology offer water resource managers in Cape Town and Perth an opportunity to learn from each other’s experiences. While Cape Town relies mostly on surface water for supply, Perth uses 50% groundwater for its domestic and industrial use. It is proposed that certain aspects of Perth’s water supply infrastructure could successfully be transposed for the exploitation of Cape Towns’ groundwater resources. In Perth private boreholes is used to tap a shallow phreatic aquifer for garden irrigation. The Government of Western Australia encourages this practice. Cape Town has an opportunity to use water from the Cape Flats Aquifer in a similar manner. In this paper the use of the Cape Flats Aquifer for private garden irrigation is evaluated. By encouraging private landowners to develop private wells, large savings could be made in the amount of treated bulk water supply required by Cape Town. The Cape Flats Aquifer has the potential to meet a large part of the city’s garden irrigation requirements. Though the impact of pollution on water quality remains uncertain and a concern, the general quality of water in the aquifer is adequate for irrigation requirements. If the use of private garden boreholes is to be successful, education of the public will be vital. It is envisaged that the City of Cape Town and the Department of Water Affairs and Forestry in partnership with private, education and research institutions take the lead in such education and the development of appropriate legislation and guidelines.
2nd WARFSA/WaterNet Symposium: Integrated Water Resources Management: Theory, Practice, Cases; Cape Town, 30-31 October 2001
The use of garden boreholes in Cape Town, South Africa: Lessons learnt from Perth, Western Australia 331
The use of garden boreholes in Cape Town, South Africa: Lessons learnt from Perth,
Western Australia
I. C. SAAYMAN1 and S. ADAMS2
1Water Programme, CSIR, PO Box 320, Stellenbosch, 7599
2Groundwater Group, Earth Science Department, University of the Western Cape,
Private Bag X17, Bellville, 7535
1 isaayman@csir.co.za
ABSTRACT
The similarities in climate and geology offer water resource managers in Cape Town and Perth an
opportunity to learn from each other’s experiences. While Cape Town relies mostly on surface
water for supply, Perth uses 50 % groundwater for its domestic and industrial use. It is proposed
that certain aspects of Perth’s water supply infrastructure could successfully be transposed for the
exploitation of Cape Towns’ groundwater resources. In Perth private boreholes is used to tap a
shallow phreatic aquifer for garden irrigation. The Government of Western Australia encourages
this practice. Cape Town has an opportunity to use water from the Cape Flats Aquifer in a similar
manner. In this paper the use of the Cape Flats Aquifer for private garden irrigation is evaluated.
By encouraging private landowners to develop private wells, large savings could be made in the
amount of treated bulk water supply required by Cape Town. The Cape Flats Aquifer has the
potential to meet a large part of the city’s garden irrigation requirements. Though the impact of
pollution on water quality remains uncertain and a concern, the general quality of water in the
aquifer is adequate for irrigation requirements. If the use of private garden boreholes is to be
successful, education of the public will be vital. It is envisaged that the City of Cape Town and the
Department of Water Affairs and Forestry in partnership with private, education and research
institutions take the lead in such education and the development of appropriate legislation and
guidelines.
Keywords: Cape Flats Aquifer; garden boreholes; groundwater management
INTRODUCTION
Groundwater has played an important role in the economic and social development of both South
Africa and Australia. The history of water resources development in the two countries has resulted
in disparate emphases on the present day use of groundwater. While water supply in Cape Town
has largely focused on the use of surface water resources, Perth largely uses groundwater for
domestic water supply. As a consequence of its focus on using groundwater, Perth has seen a
proliferation of domestic boreholes used for garden irrigation. This strategy has resulted in savings
in the city’s treated water use. An opportunity exists for Cape Town to implement a similar strategy
as a means of more effective water resources management.
This paper evaluates the feasibility of using privately owned boreholes and wellpoints in the Cape
Town Metropolitan Area for garden irrigation. In most of the suburbs in the City of Cape Town
water applied to household and public gardens, sports fields and recreational areas constitutes a
large part of the city’s annual treated water use. In Perth the use of garden boreholes as an
alternative to potable water for garden irrigation is successful. Cape Town is increasingly being
faced with the water shortages and a rapidly growing population. New and innovative strategies
are thus required to address the city’s water resource challenges. The similarity in climate and
geology that Cape Town shares with Perth offers it a unique learning opportunity. One such lesson
2nd WARFSA/WaterNet Symposium: Integrated Water Resources Management: Theory, Practice, Cases; Cape Town, 30-31 October 2001
The use of garden boreholes in Cape Town, South Africa: Lessons learnt from Perth, Western Australia 332
may be that the use of garden boreholes can be an effective measure in sustainable water
resources management.
Geographical Setting
Cape Town and Perth are located on a similar latitude and share a common climatic regime
(Figure 1). Located at the southern tip of Africa, Cape Town finds itself surrounded by ocean and
prominent mountain ranges. Reaching heights of up to 2000 meters above sea level these
mountains provide a natural barrier to rain bearing frontal systems approaching the African
continent from the south Atlantic. As a result, high rainfall is recorded on Table Mountain and in the
high mountains found to the north and northeast of Cape Town. Values recorded vary between
about 1800 mm/annum on Table Mountain to about 3800 mm/annum in Jonkershoek and near
Franshoek (Le Maitre, pers. comm., 2001, Wicht, et al., 1969).
The topographic low, located between Table Mountain and the Drakenstein and Hottentotsholland
mountains, is known as the Cape Flats. Average rainfall over the area of the Cape Flats is much
less than in the surrounding mountains, and averages about 600 mm per annum, with most rainfall
occurring during winter (see Figure 2). Large parts of the Cape Flats are covered by urban
development. Today most of the city’s population lives within the area of the Cape Flats. Based on
1996 census figures (Statistics South Africa, 1996) the 2001 population of the larger Cape Town
Metropolitan area was estimated at just over 3 million (Dorrington, 2000).
The city of Perth is located on the southwest corner of Australia. With a population of 1.4 million it
is by far the largest urban centre in Western Australia. With a relative abundance of land, most of
the population live in detached houses with large gardens. A Mediterranean climate characterized
by wet winters and dry summers means that most households require garden irrigation for large
parts of the year. The city is located on the highly permeable Swan Coastal Plain, of quaternary
sand and limestone, which is separated from the crystalline rocks of the Darling Range by the
Darling scarp. Average annual rainfall for Perth ranges between 700 and 1300 mm per year (see
Figure 2), while average annual evaporation is about 1800 mm per year (Sililo and Appleyard, in
print).
Perth
Cape
Town
Figure 1: Locations of Cape Town and Perth
2nd WARFSA/WaterNet Symposium: Integrated Water Resources Management: Theory, Practice, Cases; Cape Town, 30-31 October 2001
The use of garden boreholes in Cape Town, South Africa: Lessons learnt from Perth, Western Australia 333
0
20
40
60
80
100
120
140
160
180
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Avg. Precipitation (mm/month)
Cape Town Perth
Figure 2: Average monthly precipitation in Cape Town and Perth. (Source: South African
Weather Service and Australian Bureau of Meteorology)
HYDROGEOLOGY
Cape Town shares with Perth the occurrence of an unconsolidated shallow aquifer beneath the
city. In Cape Town it is known as the Cape Flats aquifer, while in Perth similar deposits are found
within the Swan Coastal Plain. The unconsolidated sediments of the Cape Flats Aquifer were
formed by alluvial and eolian deposition. The average thickness of the Cape Flats Aquifer deposits
is about 30m. The water table is shallow, ranging from a few centimetres below ground surface in
winter months to about 4m in summer. A secondary hard rock aquifer is found below the primary
unconsolidated aquifers consisting of Malmesbury shales and intrusive granites.
Conversely, the Swan Coastal Plain consists of highly permeable sand and sand/limestone dunes
(Appleyard, et al., 1999). These superficial sediments extend to a depth of about 100m with the
average depth being around 50m. This surficial aquifer is underlain by an extensive sedimentary
basin containing aquifer units that to a depth of up to 3000 meters.
CURRENT STATUS OF WATER SUPPLY
Cape Town
Present water resources management in Cape Town has been largely shaped by the abundance
of surface water resources in the form of perennial streams that have their origin in the mountain
ranges. With the establishment of a European settlement at the Cape by Dutch mariners in the
17th century, their choice of settlement was based on the availability of surface water resources.
Most of the water in the Cape Town Metropolitan area is derived from surface water sources.
Some municipal departments and private institutions do use groundwater and reclaimed sewage
water for irrigation. However, the use of reclaimed water is often more costly than groundwater, as
it usually requires treatment to an acceptable quality before use, and require additional
infrastructure (such as separate pipelines and pumping stations).
2nd WARFSA/WaterNet Symposium: Integrated Water Resources Management: Theory, Practice, Cases; Cape Town, 30-31 October 2001
The use of garden boreholes in Cape Town, South Africa: Lessons learnt from Perth, Western Australia 334
Perth
Perth is a growing city that experiences a continued increase in water demand. Presently the city
relies on surface reservoirs and groundwater for domestic supply. Annual domestic consumption is
about 250 million m3. Of this 50 % is derived from groundwater. However, it is estimated that an
additional 184 million m3 is abstracted from 150 000 private boreholes for garden irrigation (Water
and Rivers Commission, pers. comm., 2001, Appleyard, et al., 1999). It is estimated that 1 house
in every 4 has a private borehole that is used for garden irrigation (Appleyard, et al., 1999). Many
of these boreholes were drilled during the water restrictions of the late 1970s, and reflect the value
that is attached to private gardens. Through the use of private boreholes a great weight has been
taken off the scheme supply. In this way the city saves in the amount of treated supply needed,
thus extending the life of water supply schemes.
The use of private boreholes has not been without problem. Of particular concern is the
environmental impact of over-abstraction. One reason for this is that individuals with private
boreholes tend to use more water than those using mains water for gardens. On an average 1000
square meter house block water use for garden irrigation from mains supply ranges between 300-
600 kL/year, compared to about 1000 kl/year average borehole abstraction Water and Rivers
Commission, pers. comm., 2001).
The private boreholes are primarily used for garden irrigation and abstract water mainly from the
shallow unconfined aquifer. The City’s groundwater supply is abstracted from both the unconfined
aquifer and from deeper semi-confined aquifers. The boreholes drilled into the deep semi-confined
aquifers often exceed depths of 800m. The quality of water in both the unconfined and the deeper
aquifers is generally good, with total dissolved solids content below 250 mg/L (Appleyard, et al.,
1999).
Garden boreholes play an important role in the city’s water supply infrastructure. Through the use
of private boreholes the city’s water supply burden is lightened, saving other water resources and
money. Despite the free access that private citizens have to the Perth coastal plain aquifers,
concerns over environmental impacts and a period of exceptionally dry summers has resulted in
Perth water authorities imposing restrictions on water use, irrespective of its source. Such
restrictions include appropriate garden watering times, with a ban on daytime sprinkler use.
GARDEN BOREHOLES AS AN ALTERNATIVE
The experience of Perth in the use of private boreholes for garden irrigation has been a good one.
With so many similarities between Perth and Cape Town it begs the question on whether a similar
initiative in Cape Town would be of benefit to the city.
The use of private boreholes for garden irrigation has in Perth resulted in a reduction in the amount
treated domestic water used. The increased use of private garden boreholes in Cape Town would
similarly result in less treated domestic water being used in garden irrigation. It is estimated that
about 30% of the treated domestic supply to Cape Town water users is applied to garden irrigation
(Parsons, 2000). With annual water consumption of about 300 million m3, the potential water
saving that could be achieve should only groundwater from private wells be applied to gardens
would thus amount to about 90 million m3. The potential monetary saving to the city that this
represents is vast. Such saving result from the smaller amounts of water that will be pumped and
treated, as well as in reducing the need to invest in new bulk water supply schemes.
The fact that Cape Town receives winter rain makes it an ideal candidate for groundwater
abstraction during the dry summer months. This would relieve stress on other water sources during
the dry part of the year. With winter rains the levels in the aquifer should recover, if the aquifer is
not over exploited. By lowering water levels in summer storage in the aquifer is increased, which
reduces the risks of flooding in some of the low-lying parts of Cape Town.
2nd WARFSA/WaterNet Symposium: Integrated Water Resources Management: Theory, Practice, Cases; Cape Town, 30-31 October 2001
The use of garden boreholes in Cape Town, South Africa: Lessons learnt from Perth, Western Australia 335
In encouraging abstraction from the Cape Flats Aquifer concern about the potential of the aquifer
to meet supply will have to be addressed. Parsons (2000) quotes the estimated potential of the
Cape Flats Aquifer at about 53 million m3 per annum. If further studies show this to be correct, then
the Cape Flats Aquifer has the potential to meet a significant portion of the city’s garden irrigation
demand. The sustainable yield of the aquifer could be increased through the artificial recharge of
wastewater. Each year about 190 million m3 is discharged to the city’s rivers. Though yields vary
within the aquifer, even a lower end yield of 2 m3/hour would be sufficient to meet the irrigation
requirements of most private borehole users. This means that most of the city’s suburbs is in a
position to abstract reasonable quantities of water from the Cape Flats Aquifer.
One concern with developing large-scale abstraction is the potential impact it may have on
groundwater dependent ecosystems. Of particular concern is the impact of abstraction on wetlands
that depend on groundwater discharge. A system to address this concern has been developed in
Perth, where similar groundwater dependent wetlands exist. This has been done through the
establishment of groundwater abstraction zones, which are classified in terms of vulnerability and
recharge importance. Within sensitive zones no activities that may degrade the water quality
and/or quantity is allowed. Water managers should also guard against potential degradation of
water quality within the aquifer as a result of seawater intrusion or the induced inflow of poorer
quality water.
Before the widespread use of private garden boreholes is initiated, an evaluation of the quality of
water within the aquifer and its potential health risks will have to be evaluated. Some concern
exists about the degradation of the aquifer by industrial, commercial, informal settlement and
waste disposal activities (Fraser and Weaver, 2000b). It is however accepted the irrigation water
quality requirements are widely satisfied (Fraser and Weaver, 2000a).
WHO SHOULD DRIVE THE CAMPAIGN?
The Department of Water Affairs and Forestry (DWAF), as custodian of the country’s water
resources and the City of Cape Town should promote the efficient use of garden boreholes. An
important aspect in promoting private garden borehole use is public education. It is proposed that a
partnership be formed with the private and public sectors as well as nongovernmental and
education institutions to educate and promote the use of groundwater. Policies should be
developed by the DWAF and the City of Cape Town for the use of garden boreholes that are
aligned to National Water Strategies and Policies. Guidelines should also be developed for the
efficient and responsible usage of garden boreholes.
Any individual who wishes to install a garden borehole should need to apply to the relevant
authority for permission to install a borehole. The applicant should be legally bound to adopt an
approved technical design. The technical specification would specify the depth to which a borehole
may be drilled, the type of material to be used and the pump capacity (in order to control
abstraction) for any particular area. A GIS database needs to be developed to spatially record data
and decisions. The regulatory authority should ideally provide an advisory service, which could aid
in the fostering of a good relationship with the public. After the completion of a borehole the
relevant authority may inspect the completed borehole and approve its use. The data obtained
during the construction of the borehole should then be loaded on the GIS database.
CONSTRUCTION
The installation of garden boreholes is fairly simple in sandy aquifers. Where the water table is
close to the surface and low abstraction rates are required, shallow boreholes can often be
installed using jetting. Jetting is a technique whereby borehole screens are forced into the ground
using pressurized water. Percussion drilling is the favoured technique for drilling in hard rocks. This
2nd WARFSA/WaterNet Symposium: Integrated Water Resources Management: Theory, Practice, Cases; Cape Town, 30-31 October 2001
The use of garden boreholes in Cape Town, South Africa: Lessons learnt from Perth, Western Australia 336
may be necessary in areas where substantial iron concretions, known as ‘Koffieklip’ occur. Slotted
PVC casing is preferred as construction material because of its light weight, low cost and
durability. Depending on the depth to the water table, the borehole may be equipped with a
submersible or surface pump. The structure of a completed borehole is shown in Figure 3.
WATER QUALITY
The quality of the groundwater in the Cape Flats Aquifer is generally fresh due to the high recharge
rates. Water samples taken from the University of the Western Cape borehole site show a fresh
groundwater character in the primary aquifer and a slightly brackish water in the Secondary
Malmesbury aquifer at depth (Table 1).
Table 1 Water quality of the two aquifers tapped by the UWC borehole site and from a general
study.
Parameter Primary Aquifer Secondary Aquifer Gen. Water Quality (Fraser
and Weaver, 2000a)
Na 25.46 217.14 57
Mg 11.68 12.50 11
K 4.62 3.29 1.5
Ca 146.42 22.63 95
Si 0.37 1.09 -
Fe 2.29 0.14 -
Cl 34.50 308.15 99
HCO3 15.80 162.30
NO3-N 0.5 2.4 <0.1
pH 4.9 7.0 7.7
EC (mS/m) 78 128 78
All values in ppm unless otherwise indicated
Surface Seal
(
Cement
)
Gravel Pack
(Optional)
Aquifer
Material
Slotted Casing
(PVC)
Figure 3: Typical constructed borehole in a sandy aquifer.
2nd WARFSA/WaterNet Symposium: Integrated Water Resources Management: Theory, Practice, Cases; Cape Town, 30-31 October 2001
The use of garden boreholes in Cape Town, South Africa: Lessons learnt from Perth, Western Australia 337
The quality of the groundwater is excellent, apart form elevated levels of iron in the primary aquifer.
When used for irrigation the iron may result in staining on walls and pavements. The pH of the
primary aquifer also has a slightly acidic nature. These two variables can cause biofouling of the
screens by iron bacteria. However, with low abstraction rates the impact of this should be
insignificant.
COSTS
Where geological formations are favourable and the water table occurs close to the surface,
relatively inexpensive wellpoints can be constructed. By using jetting techniques contractors are
able to insert PVC casing up to depths of about 20 meters. Usually the cost of such an operation,
including the casing provided is in the range of R2000 to R2500. This compares well with the
comparative cost of drilling a 20 m deep borehole with air-percussion drilling, which would typically
be an order of magnitude more expensive. The cost of a centrifugal pump is about R 1000
(including connections and fittings). This means that a fully operational system can be installed for
under R 4000. This places it within the range of many households. Lower income households
however will generally not be willing to spend such an amount of capital towards garden irrigation.
The experience in Port Elizabeth, where different geological conditions exist and the cost of a
borehole is much higher, that private boreholes is almost exclusively found only in more affluent
neighbourhoods (Lomberg, et al., 1996).
ADVANTAGES AND DISADVANTAGES
As with every scheme there are advantages and disadvantages in using garden boreholes. These
are summarised in Table 2. The boreholes for garden irrigation would not require licensing but
would require some form of regulation by the relevant authorities. Large-scale abstraction in
coastal areas may cause salt-water intrusion, but this is unlikely due to the low abstraction rates
required for garden irrigation.
Table 2: The advantages and disadvantages of garden borehole use
Advantages Disadvantages
Savings in bulk water requirements Initial capital layout
Long term financial benefit Possible long term degradation of water
quality from possible saline intrusion
Devolution of maintenance from service
provider Possible soil subsidence
Job creation Possible impact on wetland systems
Research and development opportunities More groundwater quality protection and
pollution prevention required
Control water table fluctuations
The most common fear of groundwater abstraction in urban areas is that of land subsidence.
However, due to the natural groundwater level fluctuations this problem may not be very serious,
but will require additional monitoring and geotechnical research. Where abstraction is low the
water level stabilizes at a new equilibrium such that flow to the area of groundwater withdrawal
balances the abstraction (Foster et al., 1998). Irrigation return flow would also contribute to this
equilibration. The main concern would be the degradation of the water quality over time, with
pesticides, herbicides or through saline intrusion.
EDUCATION
Education and information dissemination should form an integral part of such a scheme. The main
focus would be on water conservation awareness as well using the garden boreholes responsibly.
2nd WARFSA/WaterNet Symposium: Integrated Water Resources Management: Theory, Practice, Cases; Cape Town, 30-31 October 2001
The use of garden boreholes in Cape Town, South Africa: Lessons learnt from Perth, Western Australia 338
Sensitising all role players on the importance of groundwater and the positive role it can play in
water conservation and demand management must play an important role. In Perth educational
units have been set up to run public campaigns in water resource education targeting schools and
the general public through ad campaigns (print and electronic media), competitions and
sponsorships.
The promotion of water wise gardening, including irrigation during periods of low
evapotranspiration (early mornings or just before or after sunset), drip irrigation and/or water
saving sprinkler systems, would help in preventing over exploitation of the Cape Flats aquifer.
CONCLUSIONS
The first step in encouraging widespread private garden irrigation would be through the building a
public awareness of the value of groundwater. The experience of Perth in public education could
provide water managers in Cape Town with insight on how to proceed with this. The use of private
garden boreholes will strengthen the city in its development of an integrated approach to water
resource management. It is envisaged that the use of private boreholes for garden irrigation will
form part of a larger education and water saving programme. Complimentary water saving
initiatives should also be encouraged such as rainwater harvesting and the installation of water
saving devices.
The idea of using groundwater resources is normally a progressive process that may take many
decades (Foster et al., 1998). Financial incentives for the installation of garden boreholes and
efficient water use may be required. Among the bigger challenges introduced by private garden
irrigation is the difficulty in exerting some degree of control over the large numbers of small-scale
abstractions.
If such an initiative is to work it will require the political and social will of the city’s managers and
the general public. The idea of using garden boreholes is attractive but will require more
investigation to determine its feasibility and affordability. It is recommended that a more
comprehensive study be launched to determine the feasibility of using garden boreholes for
irrigation
REFERENCES
Appleyard, S. J., Davidson, W. A., and Commander, D. P., 1999, The effects of urban
development on the utilization of groundwater resources in Perth, Western Australia, In:
Groundwater in the Urban Environment, Edited by Chilton, J., A.A. Balkema, Rotterdam, pp 97 –
104.
Department of Water Affairs and Forestry, undated, Water vir die Wes-Kaap. Pamphlet compiled
by Ninham Shand (Pty) Ltd.
Dorrington, R. E., 2000, Projections of the population of the Cape Metropolitan area 1996 – 2031,
Summary published on the City of Cape Town homepage:
http://www.capetown.gov.za/home/demographics.asp.
Forster, S; Lawrence, A and Morris, B. (1998) Groundwater in urban development. World
Technical Paper No. 390. The World Bank, Washington DC.
Fraser, L., and Weaver, J., 2000a, Cape Flats Aquifer: Bulk Water for Cape Town Now, Contract
Report submitted to Ninham Shand Consulting Engineers, Stellenbosch.
2nd WARFSA/WaterNet Symposium: Integrated Water Resources Management: Theory, Practice, Cases; Cape Town, 30-31 October 2001
The use of garden boreholes in Cape Town, South Africa: Lessons learnt from Perth, Western Australia 339
Fraser, L., and Weaver, J., 2000b, Groundwater Impact Scoping for the Cape Flats Aquifer,
Contract Report submitted to Ninham Shand Consulting Engineers, Stellenbosch.
Lomberg, C. R., and Roswarne, P. N., Raymer, D. A., and Devey, D. G., 1996, Research into
Groundwater Abstraction in the Port Elizabeth Miunicipal Area, Water Research Commission
Report, WRC Report No. 515/1/97.
Parsons, R., 2000, The role of Groundwater and its Impact on Urban Catchment Management,
The Thrid Bi Annual Symposium on Urban Catchment Management, 29 January 2000, Organised
by the Cape Metropolitan Council and the University of the Western Cape.
Sililo and Appleyard, in print, Shallow porous aquifers in Mediterranean Climates, In preparation for
UNESCO publication.
Statistics South Africa, 1996, Population Census, Pretoria.
Wicht, A. I., Meyburg, J. C., and Boustead, P. G., 1969, Rainfall at the Jonkershoek Forest
Hydrological research station, Annale Universiteit van Stellenbosch, Vol. 44, Serie A No.1. pp. 66.
  • ... Private property use of groundwater in Cape Town is already pervasive. This may be advantageous, particularly considering the efficiency of using raw water for irrigation, rather than processed potable water from the municipal supply (Saayman and Adams 2002). Some of the risks of overexploitation of aquifers such as ecological damage, saltwater intrusion and land subsidence must however be considered. ...
    ... In Cape Town's case, however, some aquifers already show a natural fluctuation in levels, and replenishment with reused water, as planned, would further mitigate the risk of overexploitation. While public education and monitoring would be recommended, the risks are not prohibitive, as shown by existing good practice studies in Australia (Saayman and Adams 2002). ...
    Article
    The infamous drought of 2015–2017 in Cape Town (South Africa) provides important lessons on water governance. While it is undeniable that an unprecedented sequence of two record-low rainfall years instigated the ‘water crisis’, this essay argues that the severity of the drought may have been mitigated by good governance, both in terms of diversifying water sources and managing existing supplies. Historically, water authorities have focussed on surface-water resources for Cape Town’s water supply. Cape Town’s ample groundwater has not been utilised to any notable extent. It is concluded that the crisis, once passed, may be viewed as auspicious, for not only did it provide the impetus to adapt Cape Town’s water supply, thereby better incorporating its groundwater resources, but the crisis stands as a case in point to justify future investments in water security, not only for Cape Town, but for other cities as well.
  • ... Estos sistemas, han presentado ventajas no sólo por la infiltración del agua y la continuidad del acuífero en términos de cantidad sino también se habla de calidad, pues los jardines retienen algunos contaminantes que el agua puede arrastrar debido a la escorrentía por suelos contaminados u otros factores (Saayman & Adams, 2002). Se sabe pues que la recarga, aumenta el volumen y reduce significativamente el sobregiro de las aguas subterráneas y la intrusión de agua de mar en la zona (Munevar & Marino, 1999). ...
    Book
    Full-text available
    El presente texto contiene los resultados del proyecto de investigación titulado “Alternativas para el manejo de aguas subterráneas en las zonas de expansión occidental de la ciudad de Pereira, Colombia”, financiado por la Universidad Tecnológica de Pereira -UTP- en el marco de la convocatoria interna del año 2010, el cual fue desarrollado por el Grupo de Investigación en Agua y Saneamiento -GIASde la Facultad de Ciencias Ambientales durante los años 2012 y 2013. La investigación se llevó a cabo en torno a la disponibilidad, calidad y explotación del recurso hídrico subterráneo y su afectación tanto en calidad como cantidad, por los procesos urbanísticos que se puedan desarrollar en zonas identificadas como estratégicas para la recarga de acuíferos y representa un reto de gran importancia para la academia y las instituciones encargadas de orientar el desarrollo del territorio con criterios de sostenibilidad económica y ambiental.
  • ... Todavia, os cidadãos que usaram esta fonte de água consumiram mais água para a irrigação, do que os que usaram outras origens. Uma sequência de verões excecionalmente secos resultou na imposição por parte da autoridade da água de Perth, de restrições ao consumo da água para rega, independente da sua origem(Saayman e Adams, 2002). Existem, assim, alguns aspetos chave que devem ser abordados(Foster e Hirata, 2011), como a promoção da gestão conjunta por parte das concessionárias dos recursos de água subterrânea e a regularização de furos privados em áreas urbanas. ...
  • ... Todavia, os cidadãos que usaram esta fonte de água consumiram mais água para a irrigação, do que os que usaram outras origens. Uma sequência de verões excecionalmente secos resultou na imposição por parte da autoridade da água de Perth, de restrições ao consumo da água para rega, independente da sua origem(Saayman e Adams, 2002). Existem, assim, alguns aspetos chave que devem ser abordados(Foster e Hirata, 2011), como a promoção da gestão conjunta por parte das concessionárias dos recursos de água subterrânea e a regularização de furos privados em áreas urbanas. ...
    Chapter
    Full-text available
    Na segunda metade do século XX registou-se uma explosão da atividade humana, associada a grandes impactos à escala global sobre o sistema da Terra. Uma das principais consequências foi o declínio dos serviços dos ecossistemas, afetando em primeiro lugar, a água e a provisão de alimentos (Berry et al., 2017). Nesta nova idade geológica designada por Antropocénico, houve uma aceleração das perturbações antrópicas nos sistemas de água subterrânea, resultante da exploração massiva deste recurso para consumo nas cidades, para a agricultura de irrigação, e, de mudanças radicais no uso do solo em áreas de recarga dos aquíferos (Foster et al., 2013). Em Lisboa existem inúmeros casos no passado e nos tempos actuais de aproveitamento de água subterrânea para fins agrícolas.
  • ... This resource is extremely valuable to regulate a continuous cropping system, of especially vegetables, throughout the year and thereby producing a continuous food source and income for the gardener (Linares, 2009). Various technologies are being developed to address water provision for sustainable gardening in Sub-Saharan Africa, but often the financial costs for such systems and general lack of education is hampering the process (Rodda, Carden, Armitage, & Du Plessis, 2011;Saayman & Adams, 2002;Woltersdorf, Jokisch, & Kluge, 2014). ...
    Article
    Rapid urbanization is predicted to take place in Africa in the near future and currently stressed cities will be even more overburdened in terms of pressure on green areas and increasing urban poverty. Effectively planning for and conserving current urban green infrastructure will be essential to ensure resilience and maintenance of quality urban environments. Gardens represent major portions of urban green infrastructure. In this paper we review literature to determine the current status of garden ecosystem services under the main themes of provisioning, regulating, supporting and cultural services in sub-Saharan Africa and identify the current challenges in optimizing these ecosystem services. Studying gardens as social-ecological systems might be the key to promote and enhance their resilience capacity in a changing world, acknowledging the fact that gardens are communities of practice in which social learning may occur. Studies on health clinic gardens in the North-West Province of South Africa have indicated how some of the challenges in terms of optimizing garden ecosystem services can be addressed. Multiple stakeholders involved in the health clinic gardens contribute towards a co-production of knowledge that could lead to social learning on aspects such as cultivation of nutritious food. More detailed studies on health clinic gardens are however, necessary to be able to develop a community-based resource management framework that can be implemented in the North-West Province and potentially in other South African provinces and countries in Sub-Saharan Africa.
  • ... Commonly industries develop groundwater self-supplies rather than purchase water from municipal utilities. Similarly, households may be tempted to drill bore wells for private use as in Perth (the Gnangara Mound case study above; Rinaudo et al. 2015); this phenomena has also been reported in other cities like Cape Town in south Africa (Saayman and Adams 2002), and southern France (Montginoul and Rinaudo 2011). ...
    Chapter
    Full-text available
    Groundwater resources are part of larger social-ecological systems. In this chapter, we review the various dimensions of these complex systems in order to uncover the diversity of elements at stake in the evolution of an aquifer and the loci for possible actions to control its dynamics. Two case studies illustrate how the state of an aquifer is embedded in a web of biophysical and sociopolitical processes. We propose here a holistic view through an IGM-scape that describes the various possible pathways of evolution for a groundwater related social-ecological system. Then we describe the elements of this IGM-scape starting with physical entities and processes, including relations with surface water and quality issues. Interactions with society bring an additional layer of considerations, including decisions on groundwater abstraction, land use changes and even energy related choices. Finally we point out the policy levers for groundwater management and their possible consequences for an aquifer, taking into account the complexity of pathways opened by these levers.
  • ... The commissioning and application of supplementary household water sources by private home owners are often drought-driven (Jacobs, 2010). Definitions of groundwater abstraction points used elsewhere are ambiguous, with the term 'garden boreholes' used by Saayman and Adams (2001) considered the most descriptive. The term groundwater abstraction point (GAP) coined by Wright and Jacobs (2010) was adopted in this manuscript to describe any type of structure for groundwater abstraction on a residential stand. ...
    Article
    Full-text available
    The potable water use recorded by 3 579 residential consumer water meters in Cape Town, South Africa, was analysed as part of this research. The focus was on selected residential properties in serviced areas, with additional private access to groundwater as a supplementary household water source. Private consumers in South Africa are not normally required to report on, or meter, groundwater use. The research team analysed records of an extensive, compulsory registration process for supplementary on-site water sources that was introduced by the City of Cape Town during the prolonged drought between 2004 and 2005. The main objective of this research was to determine the average annual water demand of residential properties serviced via the potable water distribution system, with additional registered access to a supplementary on-site groundwater source. Geo-referencing was employed to determine the approximate coordinate of each property, with subsequent one-by-one verification of each address. The data set initially contained 4 487 properties, but after filtering and verification 3 579 consumers remained in the data set for further analyses. The unique property code was identified for each verified property in order to link the attributes of consumers with access to on-site groundwater sources to their corresponding water meter records, so that the potable water demand for these stands could be analysed. The annual average water demand of the properties was subsequently obtained and analysed for two separate periods, namely, 2010 and 2014. The water use, categorised according to stand size, was similar for both periods. The results showed that consumers with access to groundwater used only about 65% of the estimated average annual water demand when compared to applicable water demand guidelines.
  • Article
    Extreme droughts can result in crippling impacts across local and regional scales. In South Africa, droughts are regular occurrences presenting several opportunities to learn from and improve on drought risk reduction efforts. Drought responses in South Africa, however, show a rather ‘messy’ reality. In the early 1990s, for example, an expanded set of various actors, not only restricted to science ‘experts’, collectively shaped and expanded the traditional drought response that had dominated in the country enabling a rethinking of risk reduction. Recent extreme droughts, occurring over 20 years later, appear to have produced interventions that have taken place with little focussed recollection of these past drought responses. A comparative assessment of the responses to droughts over time reveals some reaction but little effective ‘deep’ thinking about drought. The persistent truths of recurring drought, a failure to learn from the process of drought rather than the event, the problems of the scientific uncertainty linked to droughts and the usual crisis response to drought made by a select few, are all shown to be threats to ensuring adaptation to repeated droughts in the future.
  • Thesis
    Accès restreint aux membres de l'Université de Lorraine jusqu'au 2014-12-06
  • Article
    Recent studies on urban water demand have suggested that the water price increase observed during the last ten years in France has led to a reduction in the consumption of urban water by households. Whereas certain households have reduced their water consumption, others have turned to substitute water resources (collection of rainwater, borehole drilling, wells supplied with untreated mains water, grey water recycling systems, etc.). This article presents the results of a case study, which describes and analyses the phenomenon of resorting to untreated groundwater as a complement to or a substitute for the urban water supply. After highlighting the risks associated with uncontrolled development of private boreholes, the paper presents a survey conducted in Southern France to understand the motivations of households drilling boreholes. The results of this survey are utilised to develop a micro-economic model of households' behaviour, which is then used to assess the probability of development of private boreholes on a regional scale. The impact of various economic and regulatory scenarios on borehole development and the related impact on urban water demand and financial sustainability of water and wastewater management utilities are assessed.
  • Project Cycle Management––Integrated approach and logical framework ZOOP an introduction to the method. German Agency for Technical Cooperation Theory and Practical Appli-cation
    • References Ec
    References EC, 1993. Project Cycle Management––Integrated approach and logical framework. Commission of the European Communities (EC), Brussels. GTZ, 1988. ZOOP an introduction to the method. German Agency for Technical Cooperation, Eschborn. GTZ, 1995. GTZ Project Management, Theory and Practical Appli-cation. German Technical Cooperation, Division 601 (Personnel Development and Training), Eschborn.
  • A systems view of the logical framework matrix
    • E A Wright
    Wright, E.A., 2000. A systems view of the logical framework matrix.
  • Research into Groundwater Abstraction in the Port Elizabeth Miunicipal Area
    • C R Lomberg
    • P N Roswarne
    • D A Raymer
    • D G Devey
    Lomberg, C. R., and Roswarne, P. N., Raymer, D. A., and Devey, D. G., 1996, Research into Groundwater Abstraction in the Port Elizabeth Miunicipal Area, Water Research Commission Report, WRC Report No.
  • The role of Groundwater and its Impact on Urban Catchment Management, The Thrid Bi Annual Symposium on Urban Catchment Management
    • R Parsons
    Parsons, R., 2000, The role of Groundwater and its Impact on Urban Catchment Management, The Thrid Bi Annual Symposium on Urban Catchment Management, 29 January 2000, Organised by the Cape Metropolitan Council and the University of the Western Cape.
  • Projections of the population of the Cape Metropolitan area 1996-2031, Summary published on the City of Cape Town homepage
    • R E Dorrington
    Dorrington, R. E., 2000, Projections of the population of the Cape Metropolitan area 1996-2031, Summary published on the City of Cape Town homepage: http://www.capetown.gov.za/home/demographics.asp.
  • Rainfall at the Jonkershoek Forest Hydrological research station
    • A I Wicht
    • J C Meyburg
    • P G Boustead
    Wicht, A. I., Meyburg, J. C., and Boustead, P. G., 1969, Rainfall at the Jonkershoek Forest Hydrological research station, Annale Universiteit van Stellenbosch, Vol. 44, Serie A No.1. pp. 66.
  • Cape Flats Aquifer: Bulk Water for Cape Town Now
    • L Fraser
    • J Weaver
    Fraser, L., and Weaver, J., 2000a, Cape Flats Aquifer: Bulk Water for Cape Town Now, Contract Report submitted to Ninham Shand Consulting Engineers, Stellenbosch.
  • Shallow porous aquifers in Mediterranean Climates, In preparation for UNESCO publication
    • Appleyard Sililo
    Sililo and Appleyard, in print, Shallow porous aquifers in Mediterranean Climates, In preparation for UNESCO publication.