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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]  >> Hydrogeology of Burundi
 
[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]  >> Hydrogeology of Burundi
  
[[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]]]
 
  
One of the smallest and most densely populated countries in Africa, Burundi was an independent kingdom for over 200 years until the early 20th century. It was then colonised first by Germany, and after the First World War by Belgium, and governed with present day Rwanda as Ruanda-Urundi until independence in 1962. Initially, independent Burundi was a monarchy, but after a period of civil and military unrest the monarchy was abolished and a one-party republic established in 1966. Burundi has continued to experience multiple periods of unrest, sometimes with violence between the Hutu and Tutsi cultural groups, including two periods in which genocide was identified, first in the 1970s and then in the 1990s. Since the 1990s Burundi has had a multi-party state, but has continued to experience periods of political and military unrest, such as disrupted presidential elections and a coup attempt in 2015. After the International Criminal Court (ICC) began to investigate potential human rights crimes by the country, Burundi left the ICC in 2017.
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One of the smallest and most densely populated countries in Africa, Burundi was an independent kingdom for over 200 years until the early 20th century. In the colonial era it was colonised first by Germany, and after the First World War by Belgium, and governed with present day Rwanda as Ruanda-Urundi until independence in 1962. Initially, independent Burundi was a monarchy, but after a period of civil and military unrest the monarchy was abolished and a one-party republic established in 1966. Burundi has continued to experience multiple periods of unrest, sometimes with violence between the Hutu and Tutsi cultural groups, including two periods in which genocide was identified, first in the 1970s and then in the 1990s. Since the 1990s Burundi has had a multi-party state, but has continued to experience periods of political and military unrest, such as disrupted presidential elections and a coup attempt in 2015. After the International Criminal Court (ICC) began to investigate potential human rights crimes by the country, Burundi left the ICC in 2017.
  
Decades of civil and military unrest has left the national infrastructure in very poor state, including water and sanitation services. The population is mostly rural and employed in subsistence agriculture, but high population density and lack of land access mean many farmers can’t support themselves. Pressure to increase agricultural land has resulted in widespread deforestation. Export earnings are also dominated by agriculture (mainly coffee and tea), but these account for only a small proportion of GDP. External aid accounts for over 40% of the national income. Burundi has resources of a number of metal minerals but to date has a relatively small mining industry, of which gold provides the biggest export income. Most of the country’s electricity is produced by hydroelectric power.  
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Decades of civil and military unrest has left the national infrastructure in very poor state, including water and sanitation services. Burundi has a mostly rural population, largely employed in subsistence agriculture, but high population density and lack of land access mean many farmers can’t support themselves. Pressure to increase agricultural land has resulted in widespread deforestation. Export earnings are also dominated by agriculture (mainly coffee and tea), but these account for only a small proportion of GDP. External aid accounts for over 40% of the national income. Burundi has resources of a number of metal minerals but to date has a relatively small mining industry, of which gold provides the biggest export income. Most of the country’s electricity is produced by hydroelectric power.  
  
 
With relatively high rainfall, Burundi has relatively abundant water resources, but because rainfall and surface water are unevenly distributed both spatially and seasonally, and because water supply infrastructure is poor, there is significant pressure on water resources. Most rural communities rely on groundwater, including from numerous natural springs.  
 
With relatively high rainfall, Burundi has relatively abundant water resources, but because rainfall and surface water are unevenly distributed both spatially and seasonally, and because water supply infrastructure is poor, there is significant pressure on water resources. Most rural communities rely on groundwater, including from numerous natural springs.  
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[[File:Burundi_Geology2.png | centre| thumb| 500px| Geology of Burundi 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]].]]
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[[File:Burundi_Geology.png | centre| thumb| 500px| Geology of Burundi 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]].]]
 
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More information on the hydrogeology of Burundi is available in these documents:
 
More information on the hydrogeology of Burundi is available in these documents:
  
:- a number of reports from the groundwater project [https://www.bgr.bund.de/EN/Themen/Wasser/Projekte/laufend/TZ/Burundi/burundi_fb_en.html?nn=1546392 Management and Protection of Groundwater Resources] in Burundi carried out by BGR;  
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:- a number of reports from the groundwater project[https://www.bgr.bund.de/EN/Themen/Wasser/Projekte/laufend/TZ/Burundi/burundi_fb_en.html?nn=1546392 Management and Protection of Groundwater Resources] in Burundi carried out by BGR;  
 
:- a report by BRGM (2016) on [https://www.brgm.eu/news-media/geosciences-journal-21-africa-land-of-knowledge '''mapping groundwater availability in basement rocks'''] (page 64), which includes a map of groundwater potential in Burundi (see also Gutierrez and Barrat 2016 in References section, below); and
 
:- a report by BRGM (2016) on [https://www.brgm.eu/news-media/geosciences-journal-21-africa-land-of-knowledge '''mapping groundwater availability in basement rocks'''] (page 64), which includes a map of groundwater potential in Burundi (see also Gutierrez and Barrat 2016 in References section, below); and
 
:- a report by United Nations (1989) on [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060003 '''groundwater in Burundi'''].  
 
:- a report by United Nations (1989) on [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060003 '''groundwater in Burundi'''].  
  
[[File:Burundi_Hydrogeology2.png| 500px|thumb|center| Hydrogeology of Burundi 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]]  
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[[File:Burundi_Hydrogeology.png| 500px|thumb|center| Hydrogeology of Burundi 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]]]]
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[[File: Hydrogeology_Key.png | center| 500x195px]]
  
 
====Unconsolidated====
 
====Unconsolidated====
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|Variable Productivity (generally Low to Moderate but sometimes High)
 
|Variable Productivity (generally Low to Moderate but sometimes High)
||The productivity of the basement aquifer depends on the localised nature and extent of fracturing and weathering - how thick is the weathered zone and how developed are water-bearing fractures? A thick weathered zone - in some parts of granite and schist basement, such as at Kirundo, this can be up to 100 m (Gutierrez and Barrat 2016) - can provide significant groundwater storage potential. Where tectonic activity has caused increased rock fracturing , such as in fault zones, local basement aquifer productivity can be moderate or high. Fracturing may also, however, act to compartmentalise an aquifer  and reduce groundwater flow, which can affect the long-term sustainable yield of a borehole - for example, as suggested in Gitega in central Burundi (Pfunt et al. 2016).
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||The productivity of the basement aquifer depends on the localised nature and extent of fracturing and weathering - how thick is the weathered zone and how developed are water-bearing fractures? A thick weathered zone - in some parts of granite and schist basement rocks this can be up to 100 m - can provide significant groundwater storage potential. Where tectonic activity has caused increased rock fracturing , such as in fault zones, local basement aquifer productivity can be moderate or high. Fracturing may also, however, act to compartmentalise an aquifer  and reduce groundwater flow, which can affect the long-term sustainable yield of a borehole. This has been reported, for example, in Gitega in central Burundi (Pfunt et al. 2016).
  
 
BGR have carried out [https://www.geozentrum-hannover.de/EN/Themen/Wasser/Projekte/laufend/TZ/Burundi/burundi_fb_en.html?nn=1546392 hydrogeological studies] of the basement aquifer at sites at Gitega (the second largest city in Burundi), Kirundo and Rumonge.
 
BGR have carried out [https://www.geozentrum-hannover.de/EN/Themen/Wasser/Projekte/laufend/TZ/Burundi/burundi_fb_en.html?nn=1546392 hydrogeological studies] of the basement aquifer at sites at Gitega (the second largest city in Burundi), Kirundo and Rumonge.
  
Data from the Nyanzare wellfield at Gitega where boreholes abstract from fractured zones in the fractured schist and amphibolitic basement indicate that appropriately sited boreholes in the basement aquifer have typical transmissivity values of between 20 and 500 m<sup>2</sup>/day, possibly up to 700 m<sup>2</sup>/day (Tiberghien et al. 2014, Pfunt et al. 2016).  Borehole yields of up to 60 m<sup>3</sup>/hour are reported (Gutierrez and Barrat 2016), but compartmentalisation of the aquifer by fracturing suggests that these abstraction rates are not likely to be sustainable (Pfunt et al. 2016). [https://www.geozentrum-hannover.de/EN/Themen/Wasser/Projekte/laufend/TZ/Burundi/burundi_fb_en.html?nn=1546392 BGR] quote transmissivity values of around 35 m<sup>2</sup>/day, and borehole yields of up to 20 m<sup>3</sup>/hour, from the weathered zone of granites at Kirundo. However, more typical borehole yields across most of the basement aquifer are likely to be lower: from around <0.5 to 5 m m<sup>3</sup>/hour (Gutierrez and Barrat 2016).
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Data from a wellfield at Gitega indicate that appropriately sited boreholes in the basement aquifer have typical transmissivity values of between 20 and 500 m<sup>2</sup>/day, possibly up to 700 m<sup>2</sup>/day (Tiberghien et al. 2014, Pfunt et al. 2016).  [https://www.geozentrum-hannover.de/EN/Themen/Wasser/Projekte/laufend/TZ/Burundi/burundi_fb_en.html?nn=1546392 BGR] quote transmissivity values of around 35 m<sup>2</sup>/day, and borehole yields of up to 20 m<sup>3</sup>/hour, from the weathered zone of granites at Kirundo. Yields of up to 20 m<sup>3</sup>/hour are reported from boreholes abstracting from fractured zones in the fractured schist and amphibolitic basement in the Nyanzare wellfield at Gitega (Pfunt et al. 2016), but compartmentalisation of the aquifer by fracturing suggests that these abstraction rates are not likely to be sustainable.  
  
 
Groundwater levels (water table) in the basement aquifer at Gitega are around 15 m below ground level in the base of the valley (Pfunt et al. 2016); they may be deeper at higher elevations.
 
Groundwater levels (water table) in the basement aquifer at Gitega are around 15 m below ground level in the base of the valley (Pfunt et al. 2016); they may be deeper at higher elevations.

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