Adapting existing experience with aquifer vulnerability and groundwater protection for Africa

Robins, Nick; Chilton, P.J.; Cobbing, Jude

doi:10.1016/j.jafrearsci.2006.10.003

Cited by 41 publications

(30 citation statements)

References 8 publications

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“…All these methodologies are data intensive and require detailed knowledge of the soil cover and its properties and of the vadose zone and its physical and chemical properties. For the most part these data are not available for much of the basement aquifer system of Sub-Saharan Africa, and Robins et al (2007) argue that few of the conventional approaches to vulnerability assessment used in the 'North' are readily transferable for application in the 'South'. Besides, at local scale, features such as laterite horizons and clay grade weathering products may provide some protection to the underlying regolith aquifer.…”

Section: Introductionmentioning

confidence: 99%

A low tech approach to evaluating vulnerability to pollution of basement aquifers in sub- Saharan aquifer

Robins¹

2009

Sustainable Groundwater Resources in Africa

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The application of quantitative approaches, such as DRASTIC, to assessing groundwater vulnerability at village scale in the weathered basement aquifer of sub-Saharan Africa is questionable. This is because the techniques are data intensive and were developed for regional scale evaluation. Deconstruction of the techniques allows the key influencing parameters to be identified. These parameters can be reviewed in terms of their likely influence on the weathered basement aquifer system and ranked as being of likely high, medium or low importance. Reassembly in the form of a scorecard, using only those parameters which can be judged subjectively in the field, produces a simple vulnerability assessment technique that can be applied at village and small town scale throughout the basement aquifer of sub-Saharan Africa. It is hoped that this tried and validated technique will provide a way forward for groundwater resource vulnerability assessment in the rural savannah lands underlain by the weathered basement aquifer system. INTRODUCTIONSub-Saharan Africa has been pre-occupied with water coverage statistics for a good few years. However, water supply is not the same as safe water supply and safe water supply coverage applies to a much smaller population of the sub-continent than overall water coverage statistics would imply. Safe water derives from a water supply that is sustainable at times of water stress and which remains potable both during a prolonged and intense rain season and progressively down 'the spiral of drought ' (Calow et al., in press). In the arid and semiarid savannah lands the only sustainable water supply is groundwater because most surface waters are ephemeral and even sand river supplies may dry up periodically. Groundwater is critically important to livelihoods in these areas as it is resistant to drought, responding with a delay time behind meteoric events, be they drought or flood. However, for this same reason groundwater requires longer to recover from an extreme event than surface water, albeit seasonal water courses, but groundwater nevertheless remains the key resource over much of the weathered basement aquifer of Sub-Saharan Africa.Not all groundwater is safe water. The sight of domestic animals drinking from standing water around a village hand pump is commonplace. But commonsense dictates that animals and their faeces should be kept away from well heads and boreholes lest they contaminate the source. Commonsense also dictates that pit latrines and soakaways should be distant from water points for the same reason, and there are a number of simple guidelines to help address these issues (e.g. MacDonald et al., 2005).Not so easy is the problem of the vulnerability of the resource-rather than the source, or water point-to pollution from anthropogenic activities on the ground surface. Groundwater vulnerability is variously defined, but perhaps most appropriately, as the hydraulic inaccessibility of the saturated zone to the penetration of pollutants, combined with the attenuation c...

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Section: Introductionmentioning

confidence: 99%

A low tech approach to evaluating vulnerability to pollution of basement aquifers in sub- Saharan aquifer

Robins¹

2009

Sustainable Groundwater Resources in Africa

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“…These studies predominantly focus on water chemistry and include topics such as groundwater (redox) zonation and gradients; degree and scale of, and controls on water quality variability and spatial distribution; source apportionment; (bio)geochemical controls on contaminant degradation; reactive transport modelling; aquifer vulnerability mapping; and the determination of background/threshold concentrations (for recent papers, see, e.g. Vissers 2005;Park et al 2006;Hinkle et al 2007;Robins et al 2007;Báez-Cazull et al 2008Hinsby et al 2008;McMahon andChapelle 2007, Sochaczewski et al 2008;Spiteri et al 2008).…”

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confidence: 99%

Geochemical reactivity of subsurface sediments as potential buffer to anthropogenic inputs: a strategy for regional characterization in the Netherlands

Gaans

Griffioen

Mol³

et al. 2010

J Soils Sediments

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Purpose Sedimentary aquifers are prone to anthropogenic disturbance. Measures aimed at mitigation or adaptation require sound information on the reactivity of soil/sediments towards the infiltrating water, as this determines the chemical quality of the groundwater and receiving surface waters. Here, we address the issues of relevant sediment properties, adequate analytical methods, borehole location selection, detail of stratification, and required sample size, to develop a protocol for efficient characterization of subsurface reactivity on a regional scale. Materials and methods The sequence of geological formations in the Dutch part of the North Sea Basin is documented in the form of systematic descriptions of some 450,000 borings. The basic data are stored in a database that also includes a limited amount of geochemical data collected for specific research projects. Based on the borehole descriptions, a Digital Geological Model of the Netherlands (DGM) has recently been completed. We combined the results of a statistical analysis of the existing geochemical data with theoretical and practical considerations, to assess the degree of variability of subsurface reactivity, the relevance of different DGM-based stratifications, and the efficiency and possible redundancy of analytical parameters. Results and discussion We present two protocols for the quantitative characterization of the reactive properties of the soil and subsurface sediments of the Netherlands, down to a depth of about 30 m below surface level. As numerous strategies are already available for soil surveying, the facies-based protocol for boring and sampling is aimed at subsoil sediments. Stratification is a combination of regional, lithological, and lithostratigraphical classifications. Selection of borehole locations and sampling depths is first based on the a priori information. Given the results of the first round, additional boring, sampling and analysis are performed when necessary. The analytical protocol also applies to soil surveys. It deploys limited means to obtain the most relevant information on subsurface reactivity in view of the priority environmental issues identified. Conclusions With the progress of technologies for aquifer architecture characterization and routine chemical analysis, assessment of subsurface reactivity on a regional scale has now become feasible. Lithological stratification is essential, but regional and lithostratigraphical variability cannot be ignored. With adequate stratification, a sample size of 45 per stratum was found sufficient in most instances. The key analytes chosen appear to be statistically independent; hence, a further reduction in analytical techniques would result in serious loss of information.

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“…The reasons cited for not including these as indicators of sensitivity to vulnerability were more important than the fact that it received good quantitative support for inclusion in the vulnerability map. Reasons ranged from the fact that poor-quality groundwater and low-yielding aquifers are also socioeconomically important and thus sensitive, especially if these are the only sources of water, a view that is echoed by researchers such as Robins et al (2007). There was also the matter that poor-quality water can also be treated to potable standards.…”

Section: Overlay Indicatorsmentioning

confidence: 99%

Developing a groundwater vulnerability map for unconventional oil and gas extraction: a case study from South Africa

Esterhuyse

2017

Environ Earth Sci

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Some of the most important issues surrounding unconventional oil and gas (UOG) extraction are the possible impacts of this activity on potable groundwater resources and how to minimise and mitigate such impacts. A groundwater vulnerability map for UOG extraction has been developed as part of an interactive vulnerability map for South Africa in an effort to address such concerns and minimize possible future impacts linked to UOG extraction. This article describes the development of the groundwater theme of the interactive vulnerability map and highlights important aspects that were considered during the development of this map, which would also be of concern to other countries that may plan to embark on UOG extraction. The policy implications of the groundwater vulnerability map for managing UOG extraction impacts is also highlighted in this article.

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Adapting existing experience with aquifer vulnerability and groundwater protection for Africa

Cited by 41 publications

References 8 publications

A low tech approach to evaluating vulnerability to pollution of basement aquifers in sub- Saharan aquifer

A low tech approach to evaluating vulnerability to pollution of basement aquifers in sub- Saharan aquifer

Geochemical reactivity of subsurface sediments as potential buffer to anthropogenic inputs: a strategy for regional characterization in the Netherlands

Developing a groundwater vulnerability map for unconventional oil and gas extraction: a case study from South Africa

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