Abstract

Despite technical advances, traditional large diameter hand-dug wells remain very important in remote and rural communities as a method for gaining access to groundwater for drinking, domestic and agricultural activities. This paper explores and discusses large diameter hand-dug wells in South Africa, with regard to their utilisation, research and development, and the legislative and policy framework guiding their development and use. While large diameter hand-dug wells have featured in national legislative and policy frameworks, and in early technical guidelines, in recent years the subject has not received much attention. There is also little evidence to suggest that large diameter hand-dug wells receive any attention in typical academic and research curriculums. While South Africa's national vision is to provide improved water supply schemes in rural areas under which clean drinking water can be accessed via communal water taps, it is clear that in some rural communities household large diameter hand-dug wells still remain the most feasible and convenient way to provide water, not only for drinking but also for agricultural activities – a key form of livelihood support contributing to poverty reduction. Large diameter hand-dug wells still need attention in the policy arena to improve technical guidance to optimise the development, utilisation and management of these wells.

Introduction

Groundwater provides a practical and affordable way of meeting basic human needs for water in rural areas where it has a wide range of applications such as for drinking, domestic use, gardening and animal watering. The development of groundwater may reduce poverty and promote sustainable livelihoods, particularly in Sub-Saharan Africa (Calow et al., 2002). One of the practically affordable ways to access shallow groundwater in rural areas is through a large diameter hand-dug well. The depth of the well will most likely vary depending on site hydrogeological/geohydrological conditions and water needs. While the definition of large diameter is relative, the Department of Water and Forestry (2004a) defines a large diameter hand-dug well as having a diameter greater than 0.8 metres, allowing a single community to be able to dig and remove the excavations during installation of the well. Comprehensive details about the installation of large diameter hand-dug wells can be found in MacDonald & Davies (2000), Abbott (2001) and Department of Water and Forestry (2004a). It is also important to mention that, in some cases, hand-dug wells (tube wells) can be as small as 0.8 metres in diameter (Still et al., 2004) and are often achieved by manually driven rotary auguring while some traditional cultures wells can be as large as 15 metres in diameter (Abbott, 2001).

In South Africa, hand-dug wells have been traditionally used, though mainly confined to KwaZulu Natal Province (King, 1997; Still et al., 2004; Botha, 2016). However, in recent years, there have been commendable efforts to provide safe portable water in rural areas through modern motorised borehole community supply schemes. These typically consist of borehole water abstracted to storage/treatment tanks and then supplied to community taps where it is accessed. This water mainly serves drinking and domestic needs; for household gardens, a large diameter hand-dug well in the yard can provide much more convenience and a sense of ownership. Drought can also have devastating consequences for sustainable livelihoods and bring limited accessibility to water resources to meet basic human needs. This may lead distant communities to resort to traditional large diameter hand-dug wells if the local hydrogeological conditions are conducive. Some areas have a very low groundwater yield due to less permeable formations such that it may not be viable to install a borehole, while permeability is still sufficient to allow the accumulation of water in large diameter hand-dug wells for community use. It is therefore possible that, in some rural areas, large diameter hand-dug wells might remain useful in future. There is thus a need to better understand the status of large diameter hand-dug wells in South Africa, and perhaps a need for further research and development in the field.

This study therefore seeks to explore and discuss the status of large diameter hand-dug wells in South Africa with respect to utilisation, research and development, and the legislative and policy framework guiding their development and use. As a platform to achieve this goal, the paper first gives an overview of the legislative/policy framework that governs the development and management of groundwater resources and hand-dug wells as a means for abstracting it. A theoretical and practical perspective of the main hydrogeological/geohydrological aspects of large diameter hand-dug wells is then presented to distinguish them from boreholes. The study discusses the potential factors influencing the development and use of large diameter hand-dug wells in South Africa and highlights the policy implications they have for rural water supply and for support of livelihood activities as a contributor to poverty eradication.

Legislative and policy framework

South African legislation and policy documents concerning hand-dug wells were scrutinised to determine the availability of information on these in the country. Responsibility for the development of policies, guidelines and legislation lies with the National Department of Water and Sanitation (Formerly Department of Water Affairs – DWAF). The Minister of Water and Sanitation has overall responsible for the development of policies, guidelines and legislation and regulatory obligations.

The National Water Act (1998) (Republic of South Africa, 1998) mainly provided for reform of the law related to water resources. Sustainability and equity are the guiding principles for the protection, use, development, conservation, control and management of water resources, in accordance with the constitutional mandate for water reform. Under the Act, a Minister of the relevant water department is responsible for the use, allocation, protection and access to water resources to meet basic human needs and equity (Republic of South Africa, 1998). Information on hand-dug wells in the National Water Act is nonspecific. Section 1(ii) defines the term ‘borehole’ as an excavation, or any artificially constructed or improved underground cavity, which can be used for the interception and collection of water.

In South Africa, taking water for reasonable domestic use, including gardening and watering of animals for non-commercial purposes, is a Schedule 1 permissible use of water under the National Water Act. By nature of their small-scale operations, large diameter hand-dug wells would typically fall under Schedule 1 permissible water use which does not require any authorisation from the National Department of Water and Sanitation as long as provisions in the National Water Act are adhered to. However, recent general authorisations (Department of Water and Sanitation, 2016) for taking and storing of water under the National Water Act (1998) stipulate that it excludes alluvial aquifers directly connected to a stream. No groundwater may be abstracted within 500 m of the boundary of an estuary or wetland, within 100 m of a delineated riparian edge of a water course or a state dam, within 500 m of a state dam wall or within 500 m of the high-water mark of the ocean. It can be argued that these provisions under the ‘general authorisations’ are not applicable to hand-dug wells; however, if the total volume of groundwater taken from all hand-dug wells on a given property exceeds 10 m3 of groundwater per day, the water use must be registered. The total volume is dependent on community population size and water use activities. The registration therefore may pose a problem due to the exclusion of alluvial aquifers directly connected to a stream, as stipulated in the general authorisation exclusions, as many hand-dug wells are typically located in alluvial plains within the radius of the specifically excluded boundaries listed above.

Furthermore, this implies that water taken from hand-dug wells in communities using in excess of 10 m3 of groundwater per day can only be handled by the National Department of Water and Sanitation through a groundwater use license application. The groundwater use license application requires various specialist studies as part of the assessment. However, most rural communities in South Africa are very poor and it is highly unlikely that they would be able to afford the costs required for the specialist studies and indeed are not aware or informed of the water use authorisation requirements.

Basic hydrogeology of hand-dug wells

It is important to start by giving a conceptual overview of the main hydrogeological aspects of hand-dug wells and what distinguishes them from boreholes. A hand-dug well is excavated and constructed manually by hand, as its name implies. The level of technical expertise required for the excavation and construction of hand-dug wells varies, influenced by factors such as site conditions, affordability and location (varying from one region to another).

Hand-dug wells are typically of larger diameter than boreholes and, in the field of hydraulics, hand-dug wells are generally referred to as ‘large diameter wells’. It is mainly because of this difference in diameter that analysis of aquifer hydraulic characteristics becomes a challenge, given that the equations which are used to describe groundwater flow equations to a well assume that the diameter of a piezometer/well is infinitely small, such that storage in the well is assumed negligible (Kruseman & de Ridder, 1991); this is clearly not applicable to hand-dug wells because of their large diameter. While there are a limited number of standard methods to analyse aquifer hydraulic properties from large diameter hand-dug wells, methods have continued to evolve (Papadopulos & Cooper, 1967; Boulton & Streltsova, 1976; Rushton & Holt, 1981; Rupp et al., 2001; Yang & Yeh, 2004; MacDonald et al., 2008; Rupp et al., 2011; Rushton & de Silva, 2016).

By their nature, hand-dug wells are more suited to unconsolidated formations which make it possible to excavate manually. In principle, hand-dug wells can be installed in any formation that allows manual excavation. It is therefore possible to argue that in some hydrogeological conditions hand-dug wells can be cost effective to excavate and deliver similar yields to boreholes. A good example is an alluvial aquifer where the water bearing alluvial deposits are typically unconsolidated and can be excavated manually; the same can also be said for weathered basement aquifers. In weathered basement aquifers, boreholes are drilled deeper into the typically fractured bedrock, drawing some of the water for the overlying weathered zone. However, in highly permeable unconsolidated and weathered based basement aquifers, the influx of water during manual excavation of hand-dug wells might be a challenge, compared to a conventionally drilled borehole. In Sri Lanka (Karunaratne & Pathmarajah, 2002), in some cases large diameter wells in the weathered zone of a basement aquifer are considered a more viable option to abstract water for irrigation. Karunaratne & Pathmarajah (2002) describe the adoption of large diameter wells in the dry zone after deep drilling into the underlying hard rock aquifers had failed to provide sufficient water for irrigation.

Exploring the status of large diameter hand-dug wells in South Africa

Use of large diameter hand-dug wells

There is not much reported information in the public domain about the use of large diameter hand-dug wells in South Africa. The intention of this section is therefore not to give an overview perspective about the use of these wells in the country but to show an example of their use. While the scale of their use cannot be determined, this section serves to illustrate that they are still in use in some villages.

The few reported examples of research into hand-dug wells are generally confined to the KwaZulu Natal (KZN) Province. Traditionally hand-dug wells are common in rural areas across the Zululand Coastal Plain, as they typically exploit the shallow or unconfined aquifers found there (King, 1997). The Ubombo Family Wells Programme (UFWP) has been responsible for the construction of 500 shallow family wells in Maputaland (Still et al., 2004). Relief efforts by the Al-Imdaad Foundation to alleviate the effects of drought in Umhlabuyalingana Municipality (in KZN's Umkhanyakude District) provided boreholes in communities that have been largely reliant on large diameter hand-dug wells (Al-Imdaad Foundation, 2015); the Foundation further acknowledged that there was still a huge need for protected and safe sources of water as some villages were still reliant on unconventionally constructed open hand-dug wells. In the Umkhanyakude District Municipality region, rural communities are wholly dependent on groundwater which is extracted through hand-dug wells or boreholes, drilled for families and for communal use, respectively (Botha, 2016). It is important to highlight that most of the reported work found in literature in the public domain is confined to the influence of international partnerships and non-governmental organisations (NGOs).

Technical guidelines

There is no specific legislation dealing with the protection and management of hand-dug wells as a valuable source of water for rural communities; however, from 2000 to 2004, the Norwegian Agency for Development Cooperation (NORAD), together with the Department of Water and Forestry, embarked on the development of a toolkit for water services. This toolkit provides an overall framework and guidelines for the protection and management of groundwater in rural water supply schemes. Hand-dug wells were included, although the main focus remained on drilled boreholes. The toolkit was developed for use by water services authorities, water services providers and catchment management agencies. Village water committees – made up of community members – can also be established to assist with the management of groundwater sources (such as hand-dug wells) within their communities (Department of Water and Forestry, 2004b).

The Water Research Commission (WRC) of South Africa has a mandate to support water research and the development of sustainable water research capacity, as stipulated in the Water Research Act 1971 (Republic of South Africa, 1971). For the specific purposes of groundwater monitoring, the WRC has consistently provided guidance for groundwater sampling (Weaver, 1992; Weaver et al., 2007; WRC, 2017). The last two editions of the WRC's Groundwater Sampling Manual include procedures and techniques to collect groundwater samples from large diameter wells for the purpose of evaluating hydrogeochemical conditions and groundwater quality.

In 1996, the National Community Water and Sanitation Training Institute at the University of Limpopo was delegated by the Department of Water and Forestry to implement a groundwater training, awareness building and extension programme for rural water supply to communities. This was to include large diameter hand-dug wells as they are most convenient in rural and remote areas.

The Southern African Development Community (SADC) acknowledged that hand-dug wells are a common source of water supply in many rural areas within its remit (SADC Water Sector Coordination Unit, 2001). The installation of hand-dug wells is typically conducted by communities, international organisations and non-governmental organisations (SADC Water Sector Coordination Unit, 2001). SADC's guidelines for groundwater development in the region were developed in 2001 and include a section on hand-dug wells exploring siting, well excavation, well lining, installation of liners, slotted or perforated pre-cast concrete rings and in situ cast concrete liners, well head completions, well cover, apron and water runoff channels, as well as the upgrading of existing hand-dug wells (SADC Water Sector Coordination Unit, 2001).

Coverage of hand-dug wells in research

Academic and research activities have been investigated in order to help understand the featuring of hand-dug wells in South Africa. The Institute for Groundwater Studies (IGS) at the University of the Free State was used as a case study to assess the coverage of aspects of hand-dug wells in their research and academic activities, given that it is a specialised groundwater research and academic institute.

For coverage of the hand-dug well aspects in IGS's geohydrology academic and research activities, the content of the course's five modules were reviewed (Institute for Groundwater Studies, 2018). The five modules form the core concepts of groundwater in relation to the:

  • location of ideal/best drilling positions (Groundwater Geophysics module);

  • determination of aquifer parameters and yield (Groundwater Hydraulics module);

  • groundwater quality assessments (Hydrogeochemistry and Pollution module); and

  • management of groundwater resources (Groundwater Modelling and Groundwater Management modules).

The review of the course materials for these five modules shows that there is no reference or mention of hand-dug wells, implying that they may not be covered in the academic curriculum. It is possible to argue that the same principles used in relation to boreholes can simply be extended to large diameter hand-dug wells but the focus and emphasis can be different. Data from a geophysical survey targeted for boreholes can be useful for large diameter hand-dug wells, but the type of technology and costs associated with groundwater geophysical surveys is beyond the reach of typical rural communities. Equations used to describe and model groundwater storage and flow to wells are designed for wells of very small diameter where storage is negligible but this condition is broken in the case of large diameter hand-dug wells. Groundwater sampling for quality assessments is somewhat generic and the same principles can sometimes be used (WRC, 2017). The lack of coverage of the hand-dug well aspects in these fundamental modules (and therefore in the building blocks of understanding of groundwater science) is likely to have a negative impact on the research and development of other various aspects related to hand-dug well methodologies.

Policy implications

There are currently four water policy documents that relate to the provision of water in rural areas and which form the basis of support for the sustainable development of livelihoods and the eradication of poverty: the White Paper on Water Supply and Sanitation (Department of Water Affairs, 1994); the White Paper on a National Water Policy for South Africa (Department of Water Affairs, 1997); the White Paper on Basic Household Sanitation (Department of Water Affairs, 2001); and the Strategic Framework for Water Services (Department of Water Affairs, 2003).

Livestock and crop production are regarded as key components of a rural livelihood strategy (Ellis, 1998; Barrett et al., 2001). Depending on the scale of operation, these activities serve different livelihoods. Besides being the direct source of food, in some cases such activities can be large enough to generate additional income. In both ways, livestock and crop production at a small rural scale become important pillars for sustainability with an immense contribution towards nutrition and poverty reduction. For successful implementation of these activities, a reliable source of water is required at a rural level.

While the government is making great strides in providing higher levels of water supply to all households, including in rural areas, as directed by the policy on water services (Department of Water Affairs, 2003), it is important to remember that this relates to clean and safe water for drinking and domestic uses. In most rural areas, improved water supply schemes are used where clean water can be accessed via communal water taps, typically within a 200 m walking distance (Department of Water Affairs, 1994). Assuming that villagers can still use water from these community taps for household gardening, a walking distance of 200 m can be a hindrance to use water for any meaningful agricultural activities. Furthermore, a house hand-dug well provides a better alternative for household gardening activities, due to the ‘personal’ ownership it offers. In areas where hydrogeology conditions are suitable, a simple large diameter hand-dug well is a very cost-effective and viable option. Such a well could even be located in the garden, providing both a sense of ownership and flexibility of use. With policy driven technical guidance and training, large diameter wells can be developed and managed to provide reliable yields for small-scale commercial farming, as illustrated by examples in Sri Lanka (Rushton & de Silva, 2016).

The National Water Policy Review of 2013 was clear that the allocation and use of water should support the reduction of poverty and inequality across the country and also that the water needs of poor rural communities should be met and protected to support the development of sustainable livelihoods (Department of Water Affairs, 2013). There is, however, a lack of strategies on how traditional large diameter shallow wells can be used in conjunction with modern community water supply schemes to support the development of sustainable livelihoods and contribute towards poverty reduction in rural areas.

From a policy point of view, it therefore important to promote the development and use of large diameter hand-dug wells in rural areas where hydrogeological conditions allow for their installation, as a cost-effective way of accessing water to support livelihood-related activities. It would also be very useful to conduct some baseline studies to assess the use of large diameter hand-dug wells and to investigate other related technical needs. With respect to rural areas, policies explored could also include aspects on conjunctive use of water supply schemes and traditional hand-dug wells.

Conclusions

This study has explored and discussed the status of hand-dug wells in South African. As in other SADC countries, a large part of the efforts to provide technical hands-on guidelines for the development and exploitation of hand-dug wells can be attributed to the influence of international partnerships and NGOs. Most of the NGO work on hand-dug wells accessible in the public domain has mainly been confined to KwaZulu-Natal Province. Examples showing the use of large diameter hand-dug wells in South Africa have also been presented. It is clear that large diameter hand-dug wells will remain a convenient and affordable way to tap shallow groundwater for a variety of household livelihood uses. Although there have been huge national achievements in providing motorised borehole community water supplies, the communities still using these wells could benefit from continuous, improved technical guidance on the installation, sustainable utilisation and management of large diameter hand-dug wells that could be offered at a policy level in the country.

References

References
Abbott
S. P.
, (
2001
).
Hand Dug Wells: Choice of Technology and Construction Manual
.
Appropriate Design Choice
,
Canada
.
Al-Imdaad Foundation
(
2015
).
The Al-Imdaad Foundation Continues to the Drought Situation by Drilling Boreholes in Areas Affected by Water Shortages and Poor Access to Reliable Water
.
Available at: http://alimdaad.com/content/projectdetails.jsf?id=300 (accessed 17 August 2018)
.
Barrett
B. C.
,
Reardon
T.
&
Webb
P.
, (
2001
).
Non-farm income diversification and household livelihood strategies in rural Africa: concepts, dynamics, and policy implications
.
Food Policy
26
,
315
331
.
DOI: https://doi.org/10.1016/S0306-9192(01)00014-8
.
Botha
G. A.
, (
2016
).
Environmental and Social Impact Assessment Seismic Reflection Survey and Well Drilling, Umkhanyakude District Municipality, Northern KZN
.
Council for Geoscience, P.O. Box 900, Pietermaritzburg, 3200. Available at: www.serch.com (accessed 13 August 2018).
Boulton
N. S.
&
Streltsova
T. D.
, (
1976
).
The drawdown near an abstraction well of large diameter under non-steady conditions in an unconfined aquifer
.
Journal of Hydrology
30
,
29
46
.
DOI: https://doi.org/10.1016/0022-1694(76)90087-1
.
Calow
R. C.
,
MacDonald
A. M.
,
Nicol
A.
,
Robins
N. S.
&
Kebede
S.
, (
2002
).
The Struggle for Water: Drought, Water Security and Rural Livelihoods
.
British Geological Survey Commissioned Report CR/02/226N. Available at: http://siteresources.worldbank.org/INTWRD/864188-1171045933145/21216175/BGSStruggle.pdf (accessed 15 August 2018)
.
Department of Water Affairs
(
1994
).
Water Supply and Sanitation Policy White Paper
.
Cape Town
,
Republic of South Africa
.
Available at: http://www.dwa.gov.za/Documents/Policies/WSSP.pdf (accessed 28 September 2018)
.
Department of Water Affairs
(
1997
).
White Paper on A National Water Policy for South Africa
.
Republic of South Africa
.
Available at: https://www.gov.za/sites/default/files/nwpwp_0.pdf (accessed 2 October 2018)
.
Department of Water Affairs
(
2001
).
White Paper on Basic Household Sanitation
.
Republic of South Africa
. .
Department of Water Affairs
(
2003
).
Strategic Framework for Water Services
.
Republic of South Africa
. .
Department of Water Affairs
(
2013
).
National Water Policy Review (NWPR): Water Policy Positions. Secret Annexure A
. .
Department of Water and Forestry
(
2004a
).
Sustainability Best Practices Guidelines for Rural Water Services
.
Toolkit for Water Services, No. 7.1
.
Pretoria
,
Republic of South Africa
. .
Department of Water and Forestry
(
2004b
).
A Framework for Groundwater Management of Community Water Supply
.
Toolkit for Water Services, No. 1.1 of 2004
.
Pretoria
,
Republic of South Africa
. .
Department of Water and Sanitation
(
2016
).
Revision of General Authorisation for the Taking and Storing of Water
.
Notice of 538 of the National Water Act, 1998 (Act 36 of 1998). Government Gazette No. 40243
.
Pretoria
,
Republic of South Africa
. .
Ellis
F.
, (
1998
).
Household strategies and rural livelihood diversification
.
Journal of Development Studies
35
(
1
),
1
38
.
DOI:https://doi.org/10.1080/00220389808422553
.
Institute for Groundwater Studies
(
2018
).
2018 Calendar for BSc Honours and Master's Students Doing Certain Modules
. .
Karunaratne
A. D. M.
&
Pathmarajah
S.
, (
2002
).
Groundwater development through introduction of agrowells and micro-irrigation in Sri Lanka
. In:
Proceedings of Symposium ‘Use of Groundwater for Agriculture in Sri Lanka’
,
30 September 2002
.
Agricultural Engineering Society of Sri Lanka
,
Peradeniya
, pp.
29
41
.
King
G.
, (
1997
).
The Development Potential of KwaZulu-Natal Aquifer's for Rural Water Supply
.
MSc Thesis
,
Rhodes University
.
Available at: https://core.ac.uk/download/pdf/11985188.pdf (accessed 10 August 2018)
.
Kruseman
G. P.
&
de Ridder
N. A
, . (
1991
).
Analysis and Evaluation of Pumping Test Data
,
2nd edn
.
International Institute for Land Reclamation and Improvement
,
Wageningen
.
MacDonald
A. M.
&
Davies
J.
, (
2000
).
A Brief Review of Groundwater for Rural Water Supply in Sub-Saharan Africa
.
British Geological Survey Technical Report WC/00/33 30pp
.
BSG
,
Keyworth
,
United Kingdom
. .
MacDonald
A. M.
,
Barker
J. A.
&
Davies
J.
, (
2008
).
The bailer test: a simple effective pumping test for assessing borehole success
.
Hydrogeology Journal
16
,
1065
1075
.
DOI: https://doi.org/10.1007/s10040-008-0286-1
.
Papadopulos
I. S.
&
Cooper
H. H.
, (
1967
).
Drawdown in a well of large diameter
.
Water Resources Research
5
,
817
829
.
DOI: https://doi.org/10.1029/WR003i001p00241
.
Republic of South Africa
(
1971
).
Water Research Act, Act 34 of 1971
.
Pretoria
.
Government Gazette No. 3105. Available at: https://www.gov.za/sites/default/files/Act%2034%20of%201971.pdf (accessed 5 August 2018)
.
Republic of South Africa
(
1998
)
National Water Act, Act 36 of 1998
.
Pretoria
.
Government Gazette, pp. 1–94. Available at: http://www.dwa.gov.za/Documents/Legislature/nw_act/NWA.pdf (accessed 13 August 2018)
.
Rupp
D.
,
Selker
J.
&
Simunek
J.
, (
2001
).
A modification to the bower and rice method of slug-test analysis for large diameter, hand-dug wells
.
Ground Water
39
,
308
314
.
DOI: https://doi.org/10.1111/j.1745-6584.2001.tb02313.x
.
Rupp
D.
,
Reckmann
O.
,
Vergara
J.
,
Uribe
H.
&
Selker
J.
, (
2011
).
Unconfined aquifer permeability near hand-dug wells in the secano costero and interior, Libertador General Bernardo O'Higgins Region, Chile
.
Chilean Journal of Agricultural Research
71
,
267
274
.
DOI: http://dx.doi.org/10.4067/S0718-58392011000200012
.
Rushton
K. R.
&
de Silva
C. S.
, (
2016
).
Sustainable yields from large diameter wells in shallow weathered aquifers
.
Journal of Hydrology
539
,
495
509
.
DOI: https://doi.org/10.1016/j.jhydrol.2016.05.043
.
Rushton
R. K.
&
Holt
S. M.
, (
1981
).
Estimating aquifer parameters for large-diameter wells
.
Groundwater
19
(
5
),
505
509
.
DOI: https://doi.org/10.1111/j.1745-6584.1981.tb03501.x
.
SADC Water Sector Coordination Unit
(
2001
).
Guidelines for the Groundwater Development in the SADC Region
.
Ministry of Natural Resources
,
Lesotho
.
Still
D. A.
,
Nash
S. R.
&
MacCarthy
M. F.
, (
2004
).
South African Experience with Hand Augured Shallow Wells in Coastal Aquifers
. In:
International Water Association Water and Wastewater Management for Developing Countries (WAMDEC) Conference
,
28–30 July 2004
,
Victoria Falls, Zimbabwe
. .
Water Research Commission (WRC)
(
2017
).
Groundwater Sampling Manual
.
WRC
,
Pretoria
,
South Africa
.
WRC Report No. TT 733/17. Available at: http://www.wrc.org.za/Knowledge%20Hub%20Documents/Research%20Reports/TT%20733-17.pdf (accessed 25 September 2018)
.
Weaver
J. M. C.
, (
1992
).
Groundwater Sampling: A Comprehensive Guide for Sampling Methods
(WRC Report No. TT 54/92)
.
Water Research Commission
,
Pretoria
.
Weaver
J. M. C.
,
Cavé
L.
&
Talma
A. S.
, (
2007
).
Groundwater Sampling: A Comprehensive Guide for Sampling Methods
,
2nd edn
.
Water Research Commission (WRC)
,
Pretoria
,
Republic of South Africa
.
Report No TT 303/07. Available at: http://www.wrc.org.za/Knowledge%20Hub%20Documents/Research%20Reports/TT303-07.pdf (accessed 25 August 2018)
.
Yang
S. Y.
&
Yeh
H. D.
, (
2004
).
A simple approach using Bouwer and Rice's method for slug test data analysis
.
Ground Water
42
,
781
784
.
DOI: https://doi.org/10.1111/j.1745-6584.2004.tb02732.x
.