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[[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Sierra Leone
 
[[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Sierra Leone
 
[[File:CC-BY-SA_logo_88x31.png | frame | This work is licensed under a [https://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License]]]
 
 
Sierra Leone’s geography, including its dense tropical forest, influenced settlement and migration patterns from other areas in Africa. From the 15th century, European traders arrived, dealing primarily in slaves. By the 18th century Islam, spreading from the north and east, became widely adopted. In the late 18th century, Freetown was established as a settlement for freed slaves on land held by the British Sierra Leone company, but there was little interaction with local peoples in the interior. In the early 19th century more freed slaves were sold to the original freed slaves in what was called the ‘apprenticeship’ system. This ethnic mix created the Krio identity and language, which still dominates in Freetown. In the late 19th century the British divided Sierra Leone into a coastal colony and an inland protectorate, governing them separately until the country gained independence in 1961.
 
 
After independence Sierra Leone initially had a democratic government, but in the late 1960s increasing political authoritarianism and military coups were followed what was effectively a one-party state until 1991, with periods of military and civil unrest. A civil war began in 1991, linked to war in Liberia, which became a complex conflict between several sides. In 2002 the end of the civil war was followed by elections and a period of disarmament, justice and reconstruction. In 2014-16 Sierra Leone was severely affected by the Ebola epidemic.
 
 
The economy is dependent on mining, especially diamonds but also many other minerals and precious metals, which account for most export earnings. The proceeds of diamond mining were an incentive for the civil war and helped funded it. However, the livelihoods of most of the population rely on subsistence agriculture, with rice a key crop. Even before the civil war, mismanagement had led to economic decline, and the national economy and infrastructure was decimated by the 11 years of war. Post war reconstruction and development was set back during the Ebola outbreak.
 
 
Sierra Leone has relatively abundant water resources, but access to improved water supplies remains low. Rainfall is high although seasonal, and there are a number of major perennial rivers. However, river flow is also seasonal in response to rainfall, and surface water resources are under increasing pressure from pollution and increasing water demand. In the dry season, rural populations rely largely on groundwater.
 
  
  
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'''Mustapha Thomas''', Hydrenv Consulting, Sierra Leone
 
'''Mustapha Thomas''', Hydrenv Consulting, Sierra Leone
  
'''Dr Imogen Bellwood-Howard''', Institute of Development Studies, UK
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Please cite this page as: Upton, Ó Dochartaigh & Thomas, 2016.
  
Please cite this page as: Upton, Ó Dochartaigh, Thomas and Bellwood-Howard, 2018.
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Bibliographic reference: Upton, K., Ó Dochartaigh, B.É. & Thomas, M. 2016. Africa Groundwater Atlas: Hydrogeology of Sierra Leone. British Geological Survey. Accessed [date you accessed the information]. http://earthwise.bgs.ac.uk/index.php/Hydrogeology_of_Sierra_Leone
 
Bibliographic reference: Upton K, Ó Dochartaigh , Thomas M and Bellwood-Howard, I. 2018. Africa Groundwater Atlas: Hydrogeology of Sierra Leone. British Geological Survey. Accessed [date you accessed the information]. http://earthwise.bgs.ac.uk/index.php/Hydrogeology_of_Sierra_Leone
 
  
 
==Terms and conditions==
 
==Terms and conditions==
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[[File:Sierra Leone_Political.png | right | frame | Sierra Leone. Map developed from USGS GTOPOPO30; GADM global administrative areas; and UN Revision of World Urbanization Prospects. For more information on the map development and datasets see the [[Geography | geography resource page]].]]   
 
[[File:Sierra Leone_Political.png | right | frame | Sierra Leone. Map developed from USGS GTOPOPO30; GADM global administrative areas; and UN Revision of World Urbanization Prospects. For more information on the map development and datasets see the [[Geography | geography resource page]].]]   
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===General===
  
===General===
 
  
 
{| class = "wikitable"
 
{| class = "wikitable"
 
|-
 
|-
|Capital city || Freetown
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|Estimated Population in 2013* || 6,092,075
 
|-
 
|-
|Region || Western Africa
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|Rural Population (% of total) (2013)* || 60.8%
 
|-
 
|-
|Border countries || Guinea, Liberia
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|Total Surface Area* || 72,180 sq km
 
|-
 
|-
|Total surface area* || km<sup>2</sup>  (19,671,000 ha)
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|Agricultural Land (% of total area) (2012)* || 56.8%
 
|-
 
|-
|Total population (2015)* || 15,129,000
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|Capital City || Freetown
 
|-
 
|-
|Rural population (2015)* ||8,585,000 (56%)
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|Region || Western Africa
 
|-
 
|-
|Urban population (2015)* || 6,544,000 (44%)
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|Border Countries || Guinea, Liberia
 
|-
 
|-
|UN Human Development Index (HDI) [highest = 1] (2014)*|| 0.4659
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|Annual Freshwater Withdrawal (2013)* || 212.2 Million cubic metres
 +
|-
 +
|Annual Freshwater Withdrawal for Agriculture (2013)* || 21.5%
 +
|-
 +
|Annual Freshwater Withdrawal for Domestic Use (2013)* || 52.3%
 +
|-
 +
|Annual Freshwater Withdrawal for Industry (2013)* || 26.2%
 +
|-
 +
|Rural Population with Access to Improved Water Source (2012)* || 42.4%
 +
|-
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|Urban Population with Access to Improved Water Source (2012)* || 87.1%
 
|}
 
|}
  
<nowiki>*</nowiki> Source: [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en FAO Aquastat]
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<nowiki>*</nowiki> Source: World Bank
 
 
  
  
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Temperatures are relatively uniform throughout the year, ranging from 24 to 28 degrees C. Lowest temperatures are from July to September, in the middle of the rainy season, and highest temperatures are in February and March, near the  in end of the dry season (Lapworth et al. 2015).  
 
Temperatures are relatively uniform throughout the year, ranging from 24 to 28 degrees C. Lowest temperatures are from July to September, in the middle of the rainy season, and highest temperatures are in February and March, near the  in end of the dry season (Lapworth et al. 2015).  
  
[[File:Sierra Leone_ClimateZones.png | 375x365px |Koppen Geiger Climate Zones]][[File:Sierra Leone_ClimatePrecip.png | 375x365px |Average Annual Precipitation]][[File:Sierra Leone_ClimateTemp.png | 375x365px |Average Temperature]]
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These maps and graphs were developed from the CRU TS 3.21 dataset produced by the Climatic Research Unit at the University of East Anglia, UK. For more information see the [[Climate | climate resource page]].
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<gallery widths="375px" heights=365px mode=nolines>
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File:Sierra Leone_ClimateZones.png |Koppen Geiger Climate Zones
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File:Sierra Leone_ClimatePrecip.png |Average Annual Precipitation
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File:Sierra Leone_ClimateTemp.png |Average Temperature
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</gallery>
  
[[File:Sierra Leone_pre_Monthly.png| 255x124px| Average monthly precipitation for Sierra Leone showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File:Sierra Leone_tmp_Monthly.png| 255x124px| Average monthly temperature for Sierra Leone showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File:Sierra Leone_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File:Sierra Leone_pre_Mts.png|255x124px | Monthly precipitation (blue) over the period 2000-2012 compared with the long term monthly average (red)]]
 
  
More information on average rainfall and temperature for each of the climate zones in Sierra Leone can be seen at the [[Climate of Sierra Leone | Sierra Leone climate page]].
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[[File:Sierra Leone_pre_Monthly.png| 255x124px| Average monthly precipitation for Sierra Leone showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File:Sierra Leone_tmp_Monthly.png| 255x124px| Average monthly temperature for Sierra Leone showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File:Sierra Leone_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File:Sierra Leone_pre_Mts.png|255x124px | Monthly precipitation (blue) over the period 2000-2012 compared with the long term monthly average (red)]]  
 +
  
These maps and graphs were developed from the CRU TS 3.21 dataset produced by the Climatic Research Unit at the University of East Anglia, UK. For more information see the [[Climate | climate resource page]].
+
  
 
===Surface water===
 
===Surface water===
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|
 
|
 
|}
 
|}
 
===Water statistics===
 
 
{| class = "wikitable"
 
| || 2002||2014||2015
 
|-
 
|Rural population with access to safe drinking water (%) || || || 67.3
 
|-
 
|Urban population with access to safe drinking water (%) || || || 92.9
 
|-
 
|Population affected by water related disease || No data || No data || No data
 
|-
 
|Total internal renewable water resources (cubic metres/inhabitant/year) || ||1,705 || 
 
|-
 
|Total exploitable water resources (Million cubic metres/year) || No data || No data || No data
 
|-
 
|Freshwater withdrawal as % of total renewable water resources ||5.699|| ||
 
|-
 
|Total renewable groundwater (Million cubic metres/year) ||  ||25,000 ||
 
|-
 
|Exploitable: Regular renewable groundwater (Million cubic metres/year) || No data || No data || No data
 
|-
 
|Groundwater produced internally (Million cubic metres/year) || ||3,500 || 
 
|-
 
|Fresh groundwater withdrawal (primary and secondary) (Million cubic metres/year) || No data || No data || No data
 
|-
 
|Groundwater: entering the country (total) (Million cubic metres/year) || No data || No data || No data
 
|-
 
|Groundwater: leaving the country to other countries (total) (Million cubic metres/year) || No data || No data || No data
 
|-
 
|Industrial water withdrawal (all water sources) (Million cubic metres/year) ||58 || ||
 
|-
 
|Municipal water withdrawal (all water sources) (Million cubic metres/year)  ||98|| ||
 
|-
 
|Agricultural water withdrawal (all water sources) (Million cubic metres/year) ||2,065 || ||
 
|-
 
|Irrigation water withdrawal (all water sources) <sup>1</sup> (Million cubic metres/year) || No data || No data || No data
 
|-
 
|Irrigation water requirement (all water sources) <sup>1</sup> (Million cubic metres/year) ||949.4|| ||
 
|-
 
|Area of permanent crops (ha) || ||68,000 || 
 
|-
 
|Cultivated land (arable and permanent crops) (ha) || ||3,268,000 || 
 
|-
 
|Total area of country cultivated (%) || ||16.61 || 
 
|-
 
|Area equipped for irrigation by groundwater (ha) ||10,000 || || 
 
|-
 
|Area equipped for irrigation by mixed surface water and groundwater (ha) || No data || No data || No data
 
|}
 
 
These statistics are sourced from [http://www.fao.org/nr/water/aquastat/main/index.stm FAO Aquastat]. They are the most recent available information in the Aquastat database. More information on the derivation and interpretation of these statistics can be seen on the FAO Aquastat website.
 
 
Further water and related statistics can be accessed at the [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en Aquastat Main Database].
 
 
<sup>1</sup> More information on [http://www.fao.org/nr/water/aquastat/water_use_agr/index.stm irrigation water use and requirement statistics]
 
  
 
==Geology==
 
==Geology==
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The geology map shows a simplified overview of the geology at a national scale (see the [[Geology | Geology resource page]] for more details).
 
The geology map shows a simplified overview of the geology at a national scale (see the [[Geology | Geology resource page]] for more details).
  
[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Sierra Leone geology and hydrogeology map'''].
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More information is available in the report [http://www.bgs.ac.uk/africagroundwateratlas/fulldetails.cfm?id=AGLA060003 UN (1988)] (see References section, below).
 
 
More information is available in the report [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060003 UN (1988)] (see References section, below).
 
  
 
'''Summary'''
 
'''Summary'''
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Across the country, in river valleys there are often unconsolidated alluvial deposits laid down by rivers. Along the coastal belt are extensive outcrops of coastal, marine and estuarine unconsolidated deposits.  
 
Across the country, in river valleys there are often unconsolidated alluvial deposits laid down by rivers. Along the coastal belt are extensive outcrops of coastal, marine and estuarine unconsolidated deposits.  
  
[[File:Sierra Leone_Geology3.png | center | thumb| 500px | Geology of Sierra Leone at 1:5 million scale. Based on map described by Persits et al. 2002/Furon and Lombard 1964. For more information on the map development and datasets see the [[Geology | geology resource page]]. [https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html Download a GIS shapefile of the Sierra Leone geology and hydrogeology map].]]
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[[File:Sierra Leone_Geology2.png | center | thumb| 500px | Geology of Sierra Leone at 1:5 million scale. Developed from USGS map (Persits et al. 2002). For more information on the map development and datasets see the [[Geology | geology resource page]].]]
  
  
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|}
 
|}
  
==Hydrogeology==
 
 
The hydrogeology map below shows a simplified overview  of the type and productivity of the main aquifers at a national scale (see the [[Africa Groundwater Atlas Hydrogeology Maps | Hydrogeology map resource page]] for more details).
 
  
[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Sierra Leone geology and hydrogeology map'''].
 
  
A comprehensive report on the [http://www.salgrid.org/final_report/Final_Report_20170822.pdf '''Hydrogeology of Sierra Leone'''] was published in 2017.
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==Hydrogeology==
  
Maps, data and more information on groundwater in Sierra Leone are also available through [http://www.salgrid.org/# '''SALGRID'''] - the Salone Groundwater Resources Database portal, the official data portal and repository of hydrogeological information of the Government of Sierra Leone.
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The hydrogeology map below shows a simplified overview of the type and productivity of the main aquifers at a national scale (see the [[Hydrogeology Map | Hydrogeology map resource page]] for more details).  
 
 
Other sources with information on the hydrogeology of Sierra Leone are listed in the References section, below.
 
 
 
[[File:HgOfSierraLeoneReportCover.png| right|thumb| 150px | Report cover of Hydrogeology of Sierra Leone (2017)]].
 
 
 
[[File:Sierra Leone_Hydrogeology3.png | center | thumb| 500px | Hydrogeology of Sierra Leone at 1:5 million scale. For more information on how the map was developed see the [[Africa Groundwater Atlas Hydrogeology Maps | Hydrogeology map]] resource page. [https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html Download a GIS shapefile of the Sierra Leone geology and hydrogeology map].]].
 
  
 +
More information on the hydrogeology of Sierra Leone is available in the documents listed in the References section, below.
  
 +
[[File:Sierra Leone_Hydrogeology2.png | center | thumb| 500px | Hydrogeology of Sierra Leone at 1:5 million scale. For more information on how the map was developed see the [[Hydrogeology Map | Hydrogeology map]] resource page]].
  
 
'''Summary'''
 
'''Summary'''
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At the base of the weathered zone, the underlying crystalline bedrock is often extensively fractured and not clay rich, and can store and transmit groundwater through fractures. There can also be deeper fracture zones associated with faults. The average thickness of the fractured aquifer zone is 35 m, but it can be as much as  60 m. Borehole yields are typically between 0.3 and 1.5 l/s. Groundwater flowpaths are usually longer than in the shallow weathered aquifer, and groundwater flow can be rapid over distances of tens of metres. This deeper, fractured aquifer zone is typically a more sustainable groundwater source than the upper weathered zone. It also has more potential for the natural attenuation of contaminants, because of the overlying clay zone and the longer flowpaths (Lapworth et al. 2015).
 
At the base of the weathered zone, the underlying crystalline bedrock is often extensively fractured and not clay rich, and can store and transmit groundwater through fractures. There can also be deeper fracture zones associated with faults. The average thickness of the fractured aquifer zone is 35 m, but it can be as much as  60 m. Borehole yields are typically between 0.3 and 1.5 l/s. Groundwater flowpaths are usually longer than in the shallow weathered aquifer, and groundwater flow can be rapid over distances of tens of metres. This deeper, fractured aquifer zone is typically a more sustainable groundwater source than the upper weathered zone. It also has more potential for the natural attenuation of contaminants, because of the overlying clay zone and the longer flowpaths (Lapworth et al. 2015).
 
|}
 
|}
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==Groundwater management==
 
==Groundwater management==
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==References==
 
==References==
  
The following reports provide more information on the geology and hydrogeology of Sierra Leone. Some, and others, can be accessed through the [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=listResults&title_search=&author_search=&category_search=&country_search=SL&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive]
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The following reports provide more information on the geology and hydrogeology of Sierra Leone. Some, and others, can be accessed through the [http://www.bgs.ac.uk/africagroundwateratlas/searchResults.cfm?title_search=&author_search=&category_search=&country_search=SL&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive]
  
 
Camus Y and Cukor D. 2012. [http://www.poloresources.com/PDF/Nimini_Resource_Update_NI43-101.pdf NI 43-101 Technical Report on the Resource Update Nimini Gold Project, Kono Region, Sierra Leone]. SGS Canada Inc., submitted to Polo Resources Ltd.  
 
Camus Y and Cukor D. 2012. [http://www.poloresources.com/PDF/Nimini_Resource_Update_NI43-101.pdf NI 43-101 Technical Report on the Resource Update Nimini Gold Project, Kono Region, Sierra Leone]. SGS Canada Inc., submitted to Polo Resources Ltd.  
 
Fileccia A, Teatini P, Walther C and Mastrocola P. 2017. [http://www.salgrid.org/final_report/Final_Report_20170822.pdf Hydrogeology of Sierra Leone]. Ministry of Water Resources, Freetown, Sierra Leone.
 
  
 
Flinch JF, Huedo JL, Verzi H, Gonzalez H, Gerster R, Mansaray AK, Painuly LP, Rodriguez-Blanco L, Herra A, Brisson I and Gerard J. 2009. [http://www.searchanddiscovery.com/pdfz/documents/2009/10224flinch/ndx_flinch.pdf.html The Sierra Leone-Liberia Emerging Deepwater Province]. Adapted from oral presentation at AAPG Annual Convention, Denver, Colorado, June 7-10, 2009.  
 
Flinch JF, Huedo JL, Verzi H, Gonzalez H, Gerster R, Mansaray AK, Painuly LP, Rodriguez-Blanco L, Herra A, Brisson I and Gerard J. 2009. [http://www.searchanddiscovery.com/pdfz/documents/2009/10224flinch/ndx_flinch.pdf.html The Sierra Leone-Liberia Emerging Deepwater Province]. Adapted from oral presentation at AAPG Annual Convention, Denver, Colorado, June 7-10, 2009.  
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Lapworth DJ, Carter RC, Pedley, S and MacDonald AM. 2015. [http://nora.nerc.ac.uk/510992/ Threats to groundwater supplies from contamination in Sierra Leone, with special reference to Ebola care facilities]. British Geological Survey Technical Report OR/15/009, Nottingham, UK, 87pp.  
 
Lapworth DJ, Carter RC, Pedley, S and MacDonald AM. 2015. [http://nora.nerc.ac.uk/510992/ Threats to groundwater supplies from contamination in Sierra Leone, with special reference to Ebola care facilities]. British Geological Survey Technical Report OR/15/009, Nottingham, UK, 87pp.  
  
United Nations. 1988. [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060048 Groundwater in North and West Africa: Sierra Leone]. United Nations Department of Technical Cooperation for Development and Economic Commission for Africa. Department of Technical Cooperation for Development and Economic Commission for Africa, Natural Resources/Water Series No. 18.  
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United Nations. 1988. [http://www.bgs.ac.uk/africagroundwateratlas/fulldetails.cfm?id=AGLA060048 Groundwater in North and West Africa: Sierra Leone]. United Nations Department of Technical Cooperation for Development and Economic Commission for Africa. Department of Technical Cooperation for Development and Economic Commission for Africa, Natural Resources/Water Series No. 18.  
  
  
Return to the index pages:
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==Return to the index pages==
 
[[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Sierra Leone
 
[[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Sierra Leone
  

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