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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]  >> Hydrogeology of Rwanda  
 
[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]  >> Hydrogeology of Rwanda  
  
[[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]]]
 
  
Rwanda is a small and quite densely populated country in the Great Lakes region of central Africa. It is also known as "The Land of a Thousand Hills". Rwanda has been a distinct entity from pre-colonial times. It was colonised by Germany in 1884 (as part of German East Africa), then by Belgium in 1916, before achieving independence in 1962. Ethnic tensions between the Hutu and Tutsi cultural groups led to periodic episodes of violence, including the 1994 genocide. In the aftermath of the genocide there was a period of reconciliation and justice with associated improvement in economic, health and social indicators.
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Rwanda is a small and relatively densely populated country, also known as "The Land of a Thousand Hills", in the Great Lakes region of central Africa. Rwanda as a country has been a distinct entity from pre-colonial times. It was colonised by Germany in 1884 (as part of German East Africa), then by Belgium in 1916, before gaining independence in 1962. Ethnic tensions between the Hutu and Tutsi cultural groups led to periodic episodes of violence, including the 1994 genocide. In the aftermath of the genocide there was a period of reconciliation and justice with associated improvement in economic, health and social indicators.
  
Tea and coffee cultivation are the major cash crops and growth agricultural industries, facilitated by Rwanda's climate and geography. Mining is a significant contributor to export income. The services sector has started to recover after the late 2000s recession, including banking and communications, and particularly tourism, which is now the main source of foreign income and is supported by government. This sector is boosted by the presence of mountain gorillas in uplands areas.  
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Tea and coffee cultivation are the major cash crops, facilitated by climate and geography, and are growth agricultural industries. Mining is a significant contributor to export income. The services sector has started to recover after the late 2000s recession, including banking and communications, and particularly tourism, which is now the main source of foreign income and is supported by government. This sector is boosted by the presence of mountain gorillas in uplands areas.  
  
 
Rwanda has relatively high rainfall and both surface water and groundwater resources. Two major river basins cover Rwanda – the Nile and the Congo basins – and there are many lakes and wetlands. Groundwater is the main source of water supply in rural and some urban areas: in mountain areas from springs, and in other areas from boreholes.  
 
Rwanda has relatively high rainfall and both surface water and groundwater resources. Two major river basins cover Rwanda – the Nile and the Congo basins – and there are many lakes and wetlands. Groundwater is the main source of water supply in rural and some urban areas: in mountain areas from springs, and in other areas from boreholes.  
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[[File:Rwanda_Geology2.png | center | thumb| 500px | Geology of Rwanda 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]].]]
 
[[File:Rwanda_Geology2.png | center | thumb| 500px | Geology of Rwanda 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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|Alluvium and lake sediments
 
|Alluvium and lake sediments
 
||Quaternary
 
||Quaternary
||Unconsolidated alluvium infilling valleys and forming floodplains; and lake sediments, which mainly comprise sands, silts, gravels and clays. The most significant alluvial sediments occur in the Akagera River floodplain along the eastern border with Tanzania. Smaller outcrops of alluvium are also present in river valleys across the rest of the country, but are too small to be shown on this map.  
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||Unconsolidated alluvium infilling valleys and forming floodplains; and lake sediments, mainly comprising sands, silts, gravels and clays. The most significant alluvial sediments occur in the Akagera River floodplain along the eastern border with Tanzania. Smaller outcrops of alluvium are also present in river valleys across the rest of the country, but are too small to be shown on this map.  
 
|-
 
|-
 
!colspan="4"|Volcanic rocks
 
!colspan="4"|Volcanic rocks
 
|-
 
|-
|Northern lavas; Southwestern basalts
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|
||Cenozoic (some possibly Cretaceous)
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||Cenozoic
||Volcanic rocks crop out in the north and the far west of the country, largely lava flows. Schlüter (2006) divides them into northern lavas (of Quaternary age) and southwestern basalts (of Cenozoic-Cretaceous age).  
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||Volcanic rocks crop out in the north and the far west of the country, largely lava flows. Schlüter (2006) divides them into northern lavas and southwestern basalt.  
 
|-
 
|-
 
!colspan="4"|Precambrian
 
!colspan="4"|Precambrian
A number of different units within the Precambrian are named, with complex outcrops across the country (e.g. see Schlüter 2006). These are not distinguished on this geology map because of its small scale. The main divisions are described below.
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A number of different Precambrian geological units are defined, with complex outcrops across the country, but they are not distinguished on the map because of its small scale. The main divisions are described below.
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|-
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|Granites and associated other basement rocks
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||Palaeoproterozoic
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||These 'older granites', along with granitic-gneisses and migmatites, are seen in parts of eastern and southern Rwanda.
 
|-
 
|-
 
|Metasedimentary rocks, including the Burundian Supergroup
 
|Metasedimentary rocks, including the Burundian Supergroup
||Middle Proterozoic
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||Mesoproterozoic
 
||Metasedimentary rocks, largely quartzites, metamorphosed sandstones and shales of the Burundian Supergroup, which are locally intruded by granite. These are seen across much of the country. Named geological units within the Burundian Supergroup are the Byumba, Miyove and Lower series (Schlüter 2006).
 
||Metasedimentary rocks, largely quartzites, metamorphosed sandstones and shales of the Burundian Supergroup, which are locally intruded by granite. These are seen across much of the country. Named geological units within the Burundian Supergroup are the Byumba, Miyove and Lower series (Schlüter 2006).
|-
 
|Granites and associated other basement rocks
 
||Lower Proterozoic
 
||These are sometimes called 'older granites', along with granitic-gneisses and migmatites. They are seen in parts of eastern and southern Rwanda.
 
 
|-
 
|-
 
|}
 
|}
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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 [[Africa Groundwater Atlas Hydrogeology Maps| Hydrogeology map resource page]] for more details).  
 
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).  
  
Information on groundwater in Rwanda is still relatively limited, but further detail can be found in the reports listed in the references section below, including a more detailed hydrogeological map, which is published in the [https://waterportal.rwfa.rw/report/annual-water-status-report-2016-2017 Rwanda Annual Water Status Report 2016-2017].
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Information on groundwater in Rwanda is still relatively limited, but further detail can be found in the reports listed in the references section below, including a more detailed hydrogeological map, which is published in the Rwanda Water and Forestry Authority Annual Water Status Report 2016-2017.  
  
 
[[File:Rwanda_Hydrogeology2.png | center | thumb | 500px | Hydrogeology of Rwanda 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]]  
 
[[File:Rwanda_Hydrogeology2.png | center | thumb | 500px | Hydrogeology of Rwanda 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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'''Summary'''
 
'''Summary'''
  
The most common aquifer type in Rwanda is fractured, weathered Precambrian basement. Small outcrops of volcanic rocks form aquifers in the Western Province, in the far west and on the northern border. There are many local Quaternary unconsolidated alluvial aquifers, generally forming narrow, shallow aquifers along river valleys, with the largest outcrop in the east of the country.
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Most aquifers in Rwanda are found in fractured, weathered Precambrian basement rocks - mainly granites and metasedimentary quartzites and schists.  
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Cenozoic volcanic aquifers are found in the Western Province, in the far west and on the northern border.  
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Quaternary unconsolidated alluvial aquifers generally form narrow, shallow aquifers along river valleys. The largest outcrop is in the east of the country.
  
 
====Unconsolidated====
 
====Unconsolidated====
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|-
 
|-
 
|High Productivity
 
|High Productivity
||Most of the Quaternary unconsolidated aquifers are river alluvium, and form narrow linear aquifers along river valleys. Their aquifer properties are variable, depending largely on lithology, but where alluvium is dominated by coarser grained sediment (gravel and coarse sand), storage capacity and transmissivity can be high. Aquifers are usually unconfined with a shallow water table (<15 mbgl) and form locally important water supply sources.  
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||Most of the unconsolidated sedimentary aquifers are alluvial in origin, forming narrow linear aquifers along river valleys. Aquifer properties are variable, depending largely on lithology, but where alluvium is dominated by coarser grained sediment (gravel and coarse sand), storage capacity and transmissivity can be high. Aquifers are usually unconfined with a shallow water table (<15mbgl) and form locally important water supply sources.  
 
||Recharge is generally high due to close connection with rivers and wetlands.
 
||Recharge is generally high due to close connection with rivers and wetlands.
 
|}
 
|}
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|-
 
|-
 
|Moderate Productivity
 
|Moderate Productivity
||Little is known about groundwater in the volcanic rocks in Rwanda. Highly permeable basalt layers are documented in the Sebeya catchment in north-west Rwanda [http://www.water.rw/wp-content/uploads/2018/11/20181016-Sebeya-Catchment-Plan-2018-2024-FINAL.pdf (Water for Growth Rwanda, 2018c)].
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||Little is known about groundwater in the volcanic rocks in Rwanda. Highly permeable basalt layers are documented in the Sebeya catchment in north-west Rwanda (see the Sebeya Catchment Plan listed in the References section below).  
 
|}
 
|}
  
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|-
 
|-
 
|Variable Productivity (generally Low to Moderate)
 
|Variable Productivity (generally Low to Moderate)
||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? In the eastern and western provinces groundwater is mostly found in low productivity fractured granite, gneiss and the generally more productive quartzite. A north-south trending belt of more productive metasedimentary basement rocks, including schist and quartzite, extends along the border of the western province.  
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||The productivity of basement rocks depends on the localised nature and extent of fracturing, and the presence and thickness of a weathered zone. In the eastern and western provinces groundwater is mostly found in low productivity fractured granite, gneiss and the generally more productive quartzite.  
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A north-south trending belt of more productive metasedimentary basement rocks, including schist and quartzite, extends along the border of the western province.  
 
|}
 
|}
  
 
===Groundwater Quality===
 
===Groundwater Quality===
  
Groundwater quality is monitored by the Rwanda Water and Forestry Authority (RWFA). Noted problems with groundwater quality are usually caused by poor agricultural and mining practices, or by wastewater discharge from both domestic and industrial sources. Further detail on specific groundwater quality issues identified by the monitoring programme are summarised in [https://waterportal.rwfa.rw/report/annual-water-status-report-2016-2017 Rwanda Water and Forestry Authority (2017)].
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Groundwater quality is being monitored as part of the RWFA strategy. Issues with water quality are largely caused by poor agricultural and mining practices, as well as wastewater discharge from both domestic and industrial sources. Further detail on specific water quality issues identified by the monitoring programme are summarised in the Rwanda Water and Forestry Authority Annual Water Status Report 2016-2017 (see References below).
  
 
===Groundwater use and management===
 
===Groundwater use and management===
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=== Transboundary aquifers===
 
=== Transboundary aquifers===
  
For general information about transboundary aquifers, please see the [[Transboundary aquifers | Transboundary aquifers resources page]].
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For further information about transboundary aquifers, please see the [[Transboundary aquifers | Transboundary aquifers resources page]].
  
 
==References==
 
==References==
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Rwanda Ministry of Natural Resources. 2011. [http://www.environment.gov.rw/uploads/media/Rwanda-Waterstrategy-04062011-final-1006-corrected1406_02.pdf Water Resources Management Sub-Sector Strategic Plan (2011-2015)].  
 
Rwanda Ministry of Natural Resources. 2011. [http://www.environment.gov.rw/uploads/media/Rwanda-Waterstrategy-04062011-final-1006-corrected1406_02.pdf Water Resources Management Sub-Sector Strategic Plan (2011-2015)].  
  
Rwanda Water and Forestry Authority. 2017. [https://waterportal.rwfa.rw/report/annual-water-status-report-2016-2017 Annual Water Status Report 2016-2017]
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Rwanda Water and Forestry Authority. [https://waterportal.rwfa.rw/report/annual-water-status-report-2016-2017 Annual Water Status Report 2016-2017]
  
 
Schlüter T. 2006. [http://www.geokniga.org/bookfiles/geokniga-geological-atlas-africa.pdf Geological Atlas of Africa].   
 
Schlüter T. 2006. [http://www.geokniga.org/bookfiles/geokniga-geological-atlas-africa.pdf Geological Atlas of Africa].   
  
Water for Growth Rwanda. 2018a. [http://www.water.rw/wp-content/uploads/2018/11/20181016-Upper-Nyabarongo-Catchment-Plan-2018-2024-FINAL.pdf IWRM Programme Rwanda: Upper Nyabarongo Catchment Plan 2018-2024].  
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Water for Growth Rwanda. 2018. [http://www.water.rw/wp-content/uploads/2018/11/20181016-Upper-Nyabarongo-Catchment-Plan-2018-2024-FINAL.pdf IWRM Programme Rwanda: Upper Nyabarongo Catchment Plan 2018-2024].  
  
Water for Growth Rwanda. 2018b. [http://www.water.rw/wp-content/uploads/2018/11/20181016-Nyabugogo-Catchment-Plan-2018-2024-FINAL.pdf IWRM Programme Rwanda: Nyabugogo Catchment Plan 2018-2024].  
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Water for Growth Rwanda. 2018. [http://www.water.rw/wp-content/uploads/2018/11/20181016-Nyabugogo-Catchment-Plan-2018-2024-FINAL.pdf IWRM Programme Rwanda: Nyabugogo Catchment Plan 2018-2024].  
  
Water for Growth Rwanda. 2018c. [http://www.water.rw/wp-content/uploads/2018/11/20181016-Sebeya-Catchment-Plan-2018-2024-FINAL.pdf IWRM Programme Rwanda: Sebeya Catchment Plan 2018-2024].  
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Water for Growth Rwanda. 2018. [http://www.water.rw/wp-content/uploads/2018/11/20181016-Sebeya-Catchment-Plan-2018-2024-FINAL.pdf IWRM Programme Rwanda: Sebeya Catchment Plan 2018-2024].  
  
Water for Growth Rwanda. 2018d. [http://www.water.rw/wp-content/uploads/2018/11/20181016-Muvumba-Catchment-Plan-2018-2024-FINAL.pdf IWRM Programme Rwanda: Muvumba Catchment Plan 2018-2024].  
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Water for Growth Rwanda. 2018. [http://www.water.rw/wp-content/uploads/2018/11/20181016-Muvumba-Catchment-Plan-2018-2024-FINAL.pdf IWRM Programme Rwanda: Muvumba Catchment Plan 2018-2024].  
  
 
Theunissen K, Hanon M and Fernandez N. 1991. Carte geologique du Rwanda (scale 1:250,000). Service Geologique du Rwanda et Musee Royale de l'Afrique Centrale,  Tervuren.
 
Theunissen K, Hanon M and Fernandez N. 1991. Carte geologique du Rwanda (scale 1:250,000). Service Geologique du Rwanda et Musee Royale de l'Afrique Centrale,  Tervuren.
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United Nations. 1989. [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060018 Groundwater in Eastern, Central and Southern Africa: Rwanda]. United Nations Department of Technical Cooperation for Development.
 
United Nations. 1989. [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060018 Groundwater in Eastern, Central and Southern Africa: Rwanda]. United Nations Department of Technical Cooperation for Development.
  
 
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==Return to the index pages==
Return to the index pages:
 
 
[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]  >> Hydrogeology of Rwanda  
 
[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]  >> Hydrogeology of Rwanda  
  

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