Difference between revisions of "Groundwater quality in Africa"

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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Additional Resources]] >> Groundwater Quality in Africa
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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Additional resources| Resource pages]] >> Groundwater Quality  
  
Groundwater quality can be influenced by both natural and anthropogenic processes. A detailed review of groundwater quality issues in Africa can be found in:
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Please cite page as: Africa Groundwater Atlas. 2019. Groundwater Quality. British Geological Survey. Accessed [date you accessed the information]. ''Weblink''.
  
Xu Y and Usher B (eds). 2006. Groundwater pollution in Africa. Taylor & Francis/Balkema, Netherlands.
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  This page is still in development. Please check back soon for more content.
  
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==Introduction to Groundwater Quality in Africa==
  
Some of the key issues and studies related to groundwater quality in Africa are described below.  
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Groundwater quality can be influenced by both natural and anthropogenic processes. At present there are few studies on groundwater quality for Africa, and no regional or national assessments.  Some of the key issues related to groundwater quality in Africa are described below, with some key sources of more information.
  
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==Drinking water guidelines==
  
==Geogenic Contamination==
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The World Health Organisation sets out [http://www.who.int/water_sanitation_health/publications/dwq_guidelines/en/ '''guidelines for drinking-water quality'''] (2011).
  
Geogenic contamination refers to naturally occurring elements that are generally present in groundwater due to dissolution of the aquifer material. Geogenic contaminants in groundwater, such as arsenic and fluoride, have a negative effect on human health, particularly when consumed over prolonged periods of time.
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==Groundwater quality fact sheets==
  
  
The Swiss Federal Institute of Aquatic Science and Technology (Eawag) are currently developing global probability maps of fluoride and arsenic. The first versions of these maps use measured concentrations of arsenic and fluoride from around 20,000 and 60,000 globally distributed observations points, respectively. They combine this data with available environmental information on soil, geology, climate, and topography, and use statistical methods to determine the probability of the occurrence of groundwater fluoride and arsenic concentrations above the WHO guidelines.
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The British Geological Survey collaborated with WaterAid to summarise the inorganic quality of groundwater in countries where WaterAid works.  
  
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Download [http://www.bgs.ac.uk/downloads/browse.cfm?sec=9&cat=115 '''fact sheets for groundwater quality'''] for Burkina Faso, Ethiopia, Ghana, Madagascar, Malawi, Mali, Mozambique, Nigeria, Tanzania, Uganda and Zambia. These fact sheets aim to identify inorganic constituents of risk to health that may be present in groundwater.
  
The global probability maps can be downloaded from the Eawag website:
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Download [http://www.bgs.ac.uk/downloads/browse.cfm?sec=9&cat=116 '''water quality fact sheets by element'''] for '''arsenic''', '''fluoride''', '''iodine''', '''manganese''' and '''nitrate'''. These element sheets aim to explain the nature of the health risk for each constituent, the origin and occurrence in groundwater, the means of testing and available methods of mitigation.
  
http://www.eawag.ch/forschung/qp/wrq/mitigation_framework/water-quality/risk-maps/index_EN
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Download [http://www.bgs.ac.uk/downloads/browse.cfm?sec=9&cat=117 '''fact sheets on the impact of agriculture, industry and urbanisation''']. These complement the fact sheets on specific groundwater quality parameters and countries, and should be read together with these.
  
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[[File:BurkinaFasoWaterAidFactsheet.png | 300px | thumb| center ]]
  
Further information on the methodology can be found in the following publications:
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==Geogenic contamination==
  
Amini M, Mueller K, Abbaspour KC, Rosenberg T, Afyuni M, Moller KN, Sarr M, Johnson A. 2008. Statistical Modeling of Global Geogenic Fluoride Contamination in Groundwaters. Environmental Science and Technology, 42, 3662-3668.
 
  
Amini M, Abbaspour KC, Berg M, Winkel L, Hug SJ, Hoehn E, Yang H, Johnson A. 2008. Statistical Modeling of Global Geogenic Arsenic Contamination in Groundwater. Environmental Science and Technology, 42, 3669-3675.
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Geogenic contamination refers to '''naturally occurring elements''' that are generally present in groundwater due to dissolution of the aquifer material. Geogenic contaminants in groundwater can have a negative effect on human health, particularly when consumed over prolonged periods of time. The most common geogenic contaminants are fluoride and arsenic. More than 300 million people worldwide are thought to use groundwater contaminated with fluoride or arsenic as a source of drinking water.
  
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The British Geological Survey [http://www.bgs.ac.uk/downloads/browse.cfm?sec=9&cat=116 '''fact sheets'''] give an overview of arsenic, fluoride, iodine and manganese, all of which can be geogenic contaminants in groundwater.
  
== Salinity ==
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The Swiss Federal Institute of Aquatic Science and Technology ([https://www.eawag.ch/en/ '''Eawag''']) has developed a method to assess the risk of groundwater contamination by fluoride or arsenic in a given area, using geological, topgraphical and other environmental data. The [http://www.gapmaps.org/gap.protected/ '''Groundwater Assessment Platform'''] (GAP) enables users to upload their own data and generate hazard maps for specific areas. The Groundwater Assessment Platform also hosts a Wiki site where you can find and share information about geogenic contamination, associated health risks, and mitigation options.
  
Salinity is another important groundwater quality issue that can be driven by both natural and anthropogenic processes. Processes such as sea level rise and intense evaporation can lead to naturally high salinity in groundwater, while over-abstraction, irrigation and waste disposal can exacerbate groundwater salinity issues. Salinity has important consequences for human health and agricultural productivity.
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Further information on the methodology used by Eawag can be found in these publications:
  
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Amini, M, Mueller, K, Abbaspour, K C, Rosenberg, T, Afyuni, M, Moller, K N, Sarr, M, and Johnson, A. 2008. [http://www.ncbi.nlm.nih.gov/pubmed/18546705 Statistical modeling of global geogenic fluoride contamination in groundwaters]. Environmental Science and Technology, Vol. 42, 3662–3668.
  
IGRAC have compiled a global map of groundwater salinity occurrence by extrapolating documented cases into larger areas of high probability of saline occurrence. The global salinity map can be downloaded from the IGRAC website:
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Amini, M, Abbaspour, K C, Berg, M, Winkel, L, Hug, S J, Hoehn, E, Yang, H, and Johnson, A. 2008. [http://www.ncbi.nlm.nih.gov/pubmed/18546706 Statistical modeling of global geogenic arsenic contamination in groundwater]. Environmental Science and Technology, Vol. 42, 3669–3675.
  
http://www.un-igrac.org/publications/344
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==Salinity==
  
  
== Nitrate ==
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Salinity is an important groundwater quality issue that can be driven by both natural and anthropogenic processes. Processes such as sea-level rise and intense evaporation can lead to naturally high salinity in groundwater, while overabstraction, irrigation and waste disposal can exacerbate groundwater salinity issues. Salinity has important consequences for human health and agricultural productivity.
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 +
 
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IGRAC have compiled a [http://www.un-igrac.org/news/saline-groundwater '''global map of groundwater salinity'''] by extrapolating documented cases into larger areas of high probability of saline occurrence.
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==Nitrate==
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Nitrogen occurs naturally in the environment and is essential for plant growth. Nitrogen-based fertilisers are therefore often applied to increase crop yields. Leaching from agricultural land can lead to high concentrations of nitrogen in groundwater, which can have a negative impact on both the environment and human health.
 
Nitrogen occurs naturally in the environment and is essential for plant growth. Nitrogen-based fertilisers are therefore often applied to increase crop yields. Leaching from agricultural land can lead to high concentrations of nitrogen in groundwater, which can have a negative impact on both the environment and human health.
  
 +
A British Geological Survey [http://www.bgs.ac.uk/downloads/browse.cfm?sec=9&cat=116 '''nitrate fact sheet'''] is available giving an overview of nitrate in groundwater.
  
IGRAC are currently carrying out a global assessment of nitrate contamination which will result in global scale maps of nitrate in groundwater. Further information can be found on the IGRAC website:
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IGRAC have carried out a [http://www.un-igrac.org/resource/global-assessment-nitrate-contamination-groundwater '''global assessment of nitrate contamination'''], working towards global scale maps of nitrate in groundwater.
  
http://www.un-igrac.org/publications/498
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==Urban pollution==
  
  
== Urban Pollution ==
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Urban and peri-urban areas are expanding in many parts of Africa, particularly across sub-Saharan Africa. Groundwater is often a very important source of improved drinking water in urban and peri-urban environments, but high population densities put pressure on urban groundwater resources, not only in terms of quantity but of water quality.  
 
 
Urban and peri-urban areas are expanding in many parts of Africa, particularly across sub-Saharan Africa. Groundwater is often a very important source of improved drinking water in urban and peri-urban environments however high population densities put pressure on these resources in terms of both quantity and quality.  
 
  
  
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Some of the key sources of urban pollution include:
 
Some of the key sources of urban pollution include:
*Pit latrines, which are often located close to abstraction points, particularly in densely populated peri-urban or unplanned urban settlements
 
*Sewer leakage and sewage effluent
 
*Uncontrolled disposal of household and industrial waste
 
*Peri-urban agriculture, which includes pesticides/fertilisers and livestock waste
 
*Storm water runoff
 
*Vehicle emissions, power stations and mine waste
 
  
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*pit latrines, which are often located close to abstraction points, particularly in densely populated peri-urban or unplanned urban settlements
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*sewer leakage and sewage effluent
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*uncontrolled disposal of household and industrial waste
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*peri-urban agriculture, which includes pesticides/fertilisers and livestock waste
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*storm water runoff
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*vehicle emissions, power stations and mine waste
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There are few studies looking at urban groundwater issues in Africa and those that have been carried out mainly focus on large cities and include only basic chemical and microbiological parameters.
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Some studies of urban groundwater quality in Africa are:
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Kulabako, N R, Nalubega, M, and Thunvik, R. 2007. [http://www.sciencedirect.com/science/article/pii/S0048969707003762 Study of the impact of land use and hydrogeological settings on the shallow groundwater quality in a peri-urban area of Kampala, Uganda]. Science of the Total Environment, 381 (1-3), 180-199. doi:10.1016/j.scitotenv.2007.03.035
  
There are few studies looking at urban groundwater issues in Africa and those that have been carried out mainly focus on large cities and include only basic chemical and microbiological parameters. A detailed review of urban groundwater quality issues can be found in:
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Sorensen, J P R, Chibesa, M, Pedley, S, Lapworth, D J, Nkhuwa, D C W, Stuart, M E, Gooddy, D C, Bell, R A, Chirwa, M, Kabika, J, and Liemisa, M.  2015 [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA050013
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Emerging contaminants in urban groundwater sources in Africa]. Water Research, 72, 51-63.
  
Lapworth DJ, Stuart ME, Pedley S, Nkhuwa DCW & Tijani MN. 2014. A review of urban and peri-urban groundwater quality studies in sub-Saharan Africa. British Geological Survey (Report Number)
 
  
[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Additional Resources]] >> Groundwater Quality in Africa
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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Additional resources| Resource pages]] >> Groundwater Quality  
  
  
 
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[[Category:Additional resources]]
 
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[[Category:Africa Groundwater Atlas]]

Latest revision as of 11:05, 2 July 2019

Africa Groundwater Atlas >> Resource pages >> Groundwater Quality

Please cite page as: Africa Groundwater Atlas. 2019. Groundwater Quality. British Geological Survey. Accessed [date you accessed the information]. Weblink.
  This page is still in development. Please check back soon for more content.

Introduction to Groundwater Quality in Africa

Groundwater quality can be influenced by both natural and anthropogenic processes. At present there are few studies on groundwater quality for Africa, and no regional or national assessments. Some of the key issues related to groundwater quality in Africa are described below, with some key sources of more information.

Drinking water guidelines

The World Health Organisation sets out guidelines for drinking-water quality (2011).

Groundwater quality fact sheets

The British Geological Survey collaborated with WaterAid to summarise the inorganic quality of groundwater in countries where WaterAid works.

Download fact sheets for groundwater quality for Burkina Faso, Ethiopia, Ghana, Madagascar, Malawi, Mali, Mozambique, Nigeria, Tanzania, Uganda and Zambia. These fact sheets aim to identify inorganic constituents of risk to health that may be present in groundwater.

Download water quality fact sheets by element for arsenic, fluoride, iodine, manganese and nitrate. These element sheets aim to explain the nature of the health risk for each constituent, the origin and occurrence in groundwater, the means of testing and available methods of mitigation.

Download fact sheets on the impact of agriculture, industry and urbanisation. These complement the fact sheets on specific groundwater quality parameters and countries, and should be read together with these.

BurkinaFasoWaterAidFactsheet.png

Geogenic contamination

Geogenic contamination refers to naturally occurring elements that are generally present in groundwater due to dissolution of the aquifer material. Geogenic contaminants in groundwater can have a negative effect on human health, particularly when consumed over prolonged periods of time. The most common geogenic contaminants are fluoride and arsenic. More than 300 million people worldwide are thought to use groundwater contaminated with fluoride or arsenic as a source of drinking water.

The British Geological Survey fact sheets give an overview of arsenic, fluoride, iodine and manganese, all of which can be geogenic contaminants in groundwater.

The Swiss Federal Institute of Aquatic Science and Technology (Eawag) has developed a method to assess the risk of groundwater contamination by fluoride or arsenic in a given area, using geological, topgraphical and other environmental data. The Groundwater Assessment Platform (GAP) enables users to upload their own data and generate hazard maps for specific areas. The Groundwater Assessment Platform also hosts a Wiki site where you can find and share information about geogenic contamination, associated health risks, and mitigation options.

Further information on the methodology used by Eawag can be found in these publications:

Amini, M, Mueller, K, Abbaspour, K C, Rosenberg, T, Afyuni, M, Moller, K N, Sarr, M, and Johnson, A. 2008. Statistical modeling of global geogenic fluoride contamination in groundwaters. Environmental Science and Technology, Vol. 42, 3662–3668.

Amini, M, Abbaspour, K C, Berg, M, Winkel, L, Hug, S J, Hoehn, E, Yang, H, and Johnson, A. 2008. Statistical modeling of global geogenic arsenic contamination in groundwater. Environmental Science and Technology, Vol. 42, 3669–3675.

Salinity

Salinity is an important groundwater quality issue that can be driven by both natural and anthropogenic processes. Processes such as sea-level rise and intense evaporation can lead to naturally high salinity in groundwater, while overabstraction, irrigation and waste disposal can exacerbate groundwater salinity issues. Salinity has important consequences for human health and agricultural productivity.


IGRAC have compiled a global map of groundwater salinity by extrapolating documented cases into larger areas of high probability of saline occurrence.


Nitrate

Nitrogen occurs naturally in the environment and is essential for plant growth. Nitrogen-based fertilisers are therefore often applied to increase crop yields. Leaching from agricultural land can lead to high concentrations of nitrogen in groundwater, which can have a negative impact on both the environment and human health.

A British Geological Survey nitrate fact sheet is available giving an overview of nitrate in groundwater.

IGRAC have carried out a global assessment of nitrate contamination, working towards global scale maps of nitrate in groundwater.

Urban pollution

Urban and peri-urban areas are expanding in many parts of Africa, particularly across sub-Saharan Africa. Groundwater is often a very important source of improved drinking water in urban and peri-urban environments, but high population densities put pressure on urban groundwater resources, not only in terms of quantity but of water quality.


Groundwater quality can be influenced by a large number of contaminants in the urban environment, from microbiological pathogens and heavy metals to macronutrients, herbicides and pesticides.


Some of the key sources of urban pollution include:

  • pit latrines, which are often located close to abstraction points, particularly in densely populated peri-urban or unplanned urban settlements
  • sewer leakage and sewage effluent
  • uncontrolled disposal of household and industrial waste
  • peri-urban agriculture, which includes pesticides/fertilisers and livestock waste
  • storm water runoff
  • vehicle emissions, power stations and mine waste


There are few studies looking at urban groundwater issues in Africa and those that have been carried out mainly focus on large cities and include only basic chemical and microbiological parameters.

Some studies of urban groundwater quality in Africa are:

Kulabako, N R, Nalubega, M, and Thunvik, R. 2007. Study of the impact of land use and hydrogeological settings on the shallow groundwater quality in a peri-urban area of Kampala, Uganda. Science of the Total Environment, 381 (1-3), 180-199. doi:10.1016/j.scitotenv.2007.03.035

Sorensen, J P R, Chibesa, M, Pedley, S, Lapworth, D J, Nkhuwa, D C W, Stuart, M E, Gooddy, D C, Bell, R A, Chirwa, M, Kabika, J, and Liemisa, M. 2015 [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA050013 Emerging contaminants in urban groundwater sources in Africa]. Water Research, 72, 51-63.


Africa Groundwater Atlas >> Resource pages >> Groundwater Quality