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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Côte d'Ivoire | [[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Côte d'Ivoire | ||
− | + | '''Most of the textual information on this page was taken from the chapter on Côte d'Ivoire in the report [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060034 ‘Groundwater in North and West Africa’] (UN 1988). Some of this information is outdated. If you have more recent information on the hydrogeology of Cote d'Ivoire, please get in touch.''' | |
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− | In pre-colonial times, the present day area of Republic of Côte d'Ivoire included part of a number of states, including the Gyaaman, Kong Empire, and Baoulé. Côte d'Ivoire became a protectorate of France in 1843–1844 and a French colony in 1893. During colonial rule, France promoted the development of agricultural plantations along the coast, using forced labour. Côte d'Ivoire won independence in 1960. In the first decades after independence the country was notably stable and the economy grew rapidly, while it maintained close ties to France and neighbouring countries. Since the early 1990s, Côte d'Ivoire has experienced coup d’etat and two civil wars, first from | + | In pre-colonial times, the present day area of Republic of Côte d'Ivoire included part of a number of states, including the Gyaaman, Kong Empire, and Baoulé. Côte d'Ivoire became a protectorate of France in 1843–1844 and a French colony in 1893. During colonial rule, France promoted the development of agricultural plantations along the coast, using forced labour. Côte d'Ivoire won independence in 1960. In the first decades after independence the country was notably stable and the economy grew rapidly, while it maintained close ties to France and neighbouring countries. Since the early 1990s, Côte d'Ivoire has experienced coup d’etat and two civil wars, first from 2002 – 2007 and again, following disputed elections, in 2011. |
At independence, Côte d'Ivoire had the strongest economy in West Africa, based largely on commercial agriculture for export, and it continued to develop this sector, particularly cocoa and coffee. A recession in the 1980s contributed to the increasing political unrest. Despite civil wars, falling global prices for agricultural products, and internal political pressures, the country remains the largest regional economy, largely based on agricultural and forestry product (including rubber) exports, and is the world’s largest exporter of cocoa beans. Employment opportunities attract large numbers of workers from neighbouring countries. Petroleum products also contribute to export earnings. | At independence, Côte d'Ivoire had the strongest economy in West Africa, based largely on commercial agriculture for export, and it continued to develop this sector, particularly cocoa and coffee. A recession in the 1980s contributed to the increasing political unrest. Despite civil wars, falling global prices for agricultural products, and internal political pressures, the country remains the largest regional economy, largely based on agricultural and forestry product (including rubber) exports, and is the world’s largest exporter of cocoa beans. Employment opportunities attract large numbers of workers from neighbouring countries. Petroleum products also contribute to export earnings. | ||
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[[File:Côte d'Ivoire_pre_Monthly.png| 255x124px| Average monthly precipitation for Côte d'Ivoire showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File:Côte d'Ivoire_tmp_Monthly.png| 255x124px| Average monthly temperature for Côte d'Ivoire showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File:Côte d'Ivoire_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File:Côte d'Ivoire_pre_Mts.png|255x124px | Monthly precipitation (blue) over the period 2000-2012 compared with the long term monthly average (red)]] | [[File:Côte d'Ivoire_pre_Monthly.png| 255x124px| Average monthly precipitation for Côte d'Ivoire showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File:Côte d'Ivoire_tmp_Monthly.png| 255x124px| Average monthly temperature for Côte d'Ivoire showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File:Côte d'Ivoire_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File:Côte d'Ivoire_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 Cote d'Ivoire can be seen at the [[Climate of Cote d'Ivoire | | + | More information on average rainfall and temperature for each of the climate zones in Cote d'Ivoire can be seen at the [[Climate of Cote d'Ivoire | Cote d'Ivoire climate page]]. |
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]]. | 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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|Urban population with access to safe drinking water (%) || || || || || 93.1 | |Urban population with access to safe drinking water (%) || || || || || 93.1 | ||
|- | |- | ||
− | |Population affected by water related disease | + | |Population affected by water related disease ||1,423,000 || || || || |
|- | |- | ||
|Total internal renewable water resources (cubic metres/inhabitant/year) || || || ||3,385 || | |Total internal renewable water resources (cubic metres/inhabitant/year) || || || ||3,385 || | ||
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==Geology== | ==Geology== | ||
− | This section provides a summary of the geology of Côte d'Ivoire. More information is available in the report [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060034 ‘Groundwater in North and West Africa: Côte d'Ivoire’] (UN 1988) (see References section, below). | + | This section provides a summary of the geology of Côte d'Ivoire. More information is available in the report [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060034 ‘Groundwater in North and West Africa: Côte d'Ivoire’] (UN 1988). (see References section, below). |
The geology map shows a simplified version of the geology at a national scale (see [[Geology | the Geology resources page]] for more details). | The geology map shows a simplified version of the geology at a national scale (see [[Geology | the Geology resources page]] for more details). | ||
− | + | [[File:CotedIvoire_Geology2.png | 500 px | center | thumb| Geology of Côte d'Ivoire 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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'''Summary''' | '''Summary''' | ||
− | + | A narrow strip along the southern coast forms the coastal basin. Here, sedimentary rocks of Cretaceous-Tertiary age and unconsolidated Quaternary sediments form a wedge which narrows towards the north, where it terminates at the edge of the basement rock, less than 35 km from the coast. The basin is crossed from west to east by a fault with a displacement of several thousand metres, which separates two distinct zones: | |
- to the north is a shallower basin where the sedimentary infill is not usually more than 300 m thick | - to the north is a shallower basin where the sedimentary infill is not usually more than 300 m thick | ||
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There is a series of lagoons, part of an ancient hydrographic system, which have very thick mud deposits and are now submerged. | There is a series of lagoons, part of an ancient hydrographic system, which have very thick mud deposits and are now submerged. | ||
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+ | Across the rest of the country are basement rocks. | ||
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|Continental Terminal | |Continental Terminal | ||
||Cretaceous-Tertiary | ||Cretaceous-Tertiary | ||
− | || | + | ||The lower part of the sedimentary infill in the coastal basin comprises detrital continental Tertiary (Miocene-Pliocene) formations - mostly coarse sands - and, in the deepest areas, Upper and Middle Cretaceous marine formations, mostly sandstone, including ferruginous sandstone, and clays. Together, these form the Continental Terminal formation (sometimes, the Cretaceous is treated as a separate aquifer). |
− | |- | + | |- |
− | !colspan="4"| | + | !colspan="4"|Basement (West African Shield) |
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|Birrimian | |Birrimian | ||
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||Metamorphic rocks, mainly of sedimentary origin. These are generally schists, with meta-sandstones and meta-conglomerates in places. In places there are granitic intrusions, accompanied by volcano-sedimentary formations of tuffs, breccias, and green rocks. These form bands running from north-northeast to south-southwest, and are heavily folded, sometimes vertical. | ||Metamorphic rocks, mainly of sedimentary origin. These are generally schists, with meta-sandstones and meta-conglomerates in places. In places there are granitic intrusions, accompanied by volcano-sedimentary formations of tuffs, breccias, and green rocks. These form bands running from north-northeast to south-southwest, and are heavily folded, sometimes vertical. | ||
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− | | | + | |Prebirrimian |
||Lower Precambrian | ||Lower Precambrian | ||
||The oldest basement formations include crystalline gneiss, granites and migmatites. They are most common in the west of the country (although migmatites are found everywhere). | ||The oldest basement formations include crystalline gneiss, granites and migmatites. They are most common in the west of the country (although migmatites are found everywhere). | ||
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==Hydrogeology== | ==Hydrogeology== | ||
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This section provides a summary of the hydrogeology of the main aquifers in Côte d'Ivoire. More information is available in the report [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060034 United Nations (1988)] (see References section, below). | This section provides a summary of the hydrogeology of the main aquifers in Côte d'Ivoire. More information is available in the report [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060034 United Nations (1988)] (see References section, below). | ||
− | The hydrogeology map shows a simplified version of the type and productivity of the main aquifers at a national scale (see the [[ | + | The hydrogeology map shows a simplified version of the type and productivity of the main aquifers at a national scale (see the [[Hydrogeology Map | Hydrogeology Map]] resource page for more details). |
− | + | [[File:CotedIvoire_Hydrogeology2.png | center | thumb| 500px | Hydrogeology of Côte d'Ivoire at 1:5million scale. For more information on how the map was developed see the [[Hydrogeology Map | hydrogeology map]] resource page]] | |
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'''Summary''' | '''Summary''' | ||
− | The | + | The main aquifer type in Côte d'Ivoire is in weathered and fractured basement rocks, which underlie most of the country. |
− | + | Along the coast are small sedimentary basins, with Cretaceous-Tertiary consolidated sedimentary rocks overlain by unconsolidated Quaternary sediments. '''Continental Terminal''' is the term is sometimes used to describe the whole of this coastal basin aquifer, from Cretaceous to Quaternary, and sometimes to describe only the Quaternary, or only the Tertiary, or both the Cretaceous and Tertiary formations. Here, it is used to describe the Cretaceous-Tertiary aquifer in the coastal basin that underlies the Quaternary aquifer. The Quaternary aquifer is described separately below, highlighting its unconsolidated nature and high vulnerability. | |
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|Coastal basin | |Coastal basin | ||
||Quaternary | ||Quaternary | ||
− | ||The southern part of the coastal basin consists of Quaternary formations, including coastal and marine sands. In their upper part, these form a moderately to highly productive aquifer, capable of sustaining borehole yields of at least 5 to 50 m³/hour. In some places with very permeable coarse sands, a borehole yield of at least 210 m³/hour for a drawdown of 3.1 m was recorded (a specific capacity of at least 1600 m³/day/m | + | ||The southern part of the coastal basin consists of Quaternary formations, including coastal and marine sands. In their upper part, these form a moderately to highly productive aquifer, capable of sustaining borehole yields of at least 5 to 50 m³/hour. In some places with very permeable coarse sands, a borehole yield of at least 210 m³/hour for a drawdown of 3.1 m was recorded (a specific capacity of at least 1600 m³/day/m). |
In some places there is a clay layer underlying the sand aquifer, below which is often saline water. | In some places there is a clay layer underlying the sand aquifer, below which is often saline water. | ||
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||Groundwater has moderate mineral content, with dry residues of between 250 and 500 mg/l, sometimes up to 650 mg/l, and a pH close to 7 (neutral). | ||Groundwater has moderate mineral content, with dry residues of between 250 and 500 mg/l, sometimes up to 650 mg/l, and a pH close to 7 (neutral). | ||
|- | |- | ||
− | | | + | |Granitogneiss aquifers |
− | ||Lower Precambrian | + | || Lower Precambrian |
− | || | + | ||In the quartz grained granitogneiss rocks, groundwater occurs in shallow weathered zones, where the rock has weathered to sand and gravel; and in deeper fractures in unweathered bedrock. |
The weathered zone is 20 to 30 m thick on average, but sometimes as much as 60 m. Transmissivity values for this zone are in the order of 8 to 85 m²/day. Generally speaking, the most weathered (the most sandy and gravelly) zones, which have the highest permeability, are found at the base of the weathered zone. | The weathered zone is 20 to 30 m thick on average, but sometimes as much as 60 m. Transmissivity values for this zone are in the order of 8 to 85 m²/day. Generally speaking, the most weathered (the most sandy and gravelly) zones, which have the highest permeability, are found at the base of the weathered zone. | ||
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==Groundwater Status== | ==Groundwater Status== | ||
− | + | Groundwater in the coastal Quaternary and Continental Terminal aquifers is highly vulnerable to contamination, both by seawater intrusion and by pollution from urban industry and domestic waste. Many studies have been done of the risks to and effects on groundwater, particularly in the Abidjan area (e.g. Douagui et al. 2012, Kouassi et al. 2013 and Issiaka et al. 2006). | |
− | Seawater intrusion may be caused by falling groundwater levels, which themselves may be linked to intensive groundwater pumping and/or to rainfall variability (Oga et al. 2006). | + | Seawater intrusion may be caused by falling groundwater levels, which themselves may be linked to intensive groundwater pumping and/or to rainfall variability (Oga et al. 2006). |
==Groundwater use and management== | ==Groundwater use and management== | ||
− | + | Groundwater from the Quaternary aquifer is the main source of drinking water supply in Abidjan and most of the rest of the coastal zone. Groundwater from shallow boreholes and hand dug wells in the basement aquifer is the main source of water in rural areas across the rest of the country. | |
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− | Groundwater from the Quaternary aquifer is the main source of drinking water supply in Abidjan and most of the rest of the coastal zone. Groundwater from shallow boreholes and hand dug wells in the basement aquifer is the main source of water in rural areas across the rest of the country. | ||
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− | + | At least 13,000 groundwater sources had been recorded in the country in 2008, mostly boreholes, with hand dug wells the next numerous. | |
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==References== | ==References== | ||
− | The following references provide more information on the geology and hydrogeology of | + | The following references provide more information on the geology and hydrogeology of Cote d'Ivoire. |
Many of these, and others, can be found in [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=listResults&title_search=&author_search=&category_search=&country_search=CI&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive] | Many of these, and others, can be found in [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=listResults&title_search=&author_search=&category_search=&country_search=CI&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive] | ||
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Douagui et al. 2012. [https://www.sciencedirect.com/science/article/pii/S1570644312000470 Assessment of the bacteriological quality and nitrate pollution risk of Quaternary groundwater in the southern part of Abidjan District (Côte d’Ivoire)]. Journal of Hydro-environment Research, Vol.6, Issue 3, pp 227-238 | Douagui et al. 2012. [https://www.sciencedirect.com/science/article/pii/S1570644312000470 Assessment of the bacteriological quality and nitrate pollution risk of Quaternary groundwater in the southern part of Abidjan District (Côte d’Ivoire)]. Journal of Hydro-environment Research, Vol.6, Issue 3, pp 227-238 | ||
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Issiaka et al. 2006. Vulnerability assessment of the Abidjan Quaternary aquifer using the DRASTIC method. In: Groundwater quality in Africa, ed. Y Xu and B Usher, Taylor and Francis/Balkema, Rotterdam, pp 115-124 | Issiaka et al. 2006. Vulnerability assessment of the Abidjan Quaternary aquifer using the DRASTIC method. In: Groundwater quality in Africa, ed. Y Xu and B Usher, Taylor and Francis/Balkema, Rotterdam, pp 115-124 | ||
− | JICA Report (date unknown | + | JICA Report (date unknown) - extract. Chapter 5 - [http://open_jicareport.jica.go.jp/pdf/11634250_10.pdf Geology and Groundwater] (of Côte d’Ivoire). |
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Kouamé el al. 2013. https://pdfs.semanticscholar.org/efaf/9192096b978b14d291a31660d8314276f9a9.pdf Modeling of Groundwater Flow and Drawdown Evolution Simulation of Abidjan Aquifer (Côte d’Ivoire)]. Journal of Asian Scientific Research, Vol. 3 (4), pp 344-364. | Kouamé el al. 2013. https://pdfs.semanticscholar.org/efaf/9192096b978b14d291a31660d8314276f9a9.pdf Modeling of Groundwater Flow and Drawdown Evolution Simulation of Abidjan Aquifer (Côte d’Ivoire)]. Journal of Asian Scientific Research, Vol. 3 (4), pp 344-364. | ||
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Kouamé et al. 2013. [https://www.researchgate.net/publication/268504582_Modeling_of_Quaternary_Groundwater_Pollution_Risk_by_GIS_and_Multicriteria_Analysisin_the_Southern_Part_of_Abidjan_District_Cote_d'Ivoire Modeling of Quaternary Groundwater Pollution Risk by GIS and Multicriteria Analysis in the Southern Part of Abidjan District (Côte d’Ivoire)]. Journal of Environmental Protection Vol. 4 (11), pp 1213-1223. Doi: 10.4236/jep.2013.411139 | Kouamé et al. 2013. [https://www.researchgate.net/publication/268504582_Modeling_of_Quaternary_Groundwater_Pollution_Risk_by_GIS_and_Multicriteria_Analysisin_the_Southern_Part_of_Abidjan_District_Cote_d'Ivoire Modeling of Quaternary Groundwater Pollution Risk by GIS and Multicriteria Analysis in the Southern Part of Abidjan District (Côte d’Ivoire)]. Journal of Environmental Protection Vol. 4 (11), pp 1213-1223. Doi: 10.4236/jep.2013.411139 | ||
− | + | Oga MS, Marlin C, Dever L, Filly A and Njitchoua R. 2008 . Hydrochemical and isotopic characteristics of coastal Groundwater near Abidjan. In: Adelana and MacDonald (eds) Applied Groundwater Studies in Africa, pp 371-389. | |
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− | Oga MS, Marlin C, Dever L, Filly A and Njitchoua R. 2008 . Hydrochemical and isotopic characteristics of coastal Groundwater near Abidjan. In: Adelana and MacDonald (eds) Applied Groundwater Studies in Africa | ||
Practica Foundation, UNICEF and Enterprise Works/VITA. 2014. [https://www.practica.org/wp-content/uploads/2014/10/COTE_IVOIRE_carte_finale_A2.pdf Etude de faisabilite des techniques de forages manuelle: Carte des zones favorables - Republique de la Côte d'Ivoire]. Practica/Enterprise Works/VITA/UNICEF | Practica Foundation, UNICEF and Enterprise Works/VITA. 2014. [https://www.practica.org/wp-content/uploads/2014/10/COTE_IVOIRE_carte_finale_A2.pdf Etude de faisabilite des techniques de forages manuelle: Carte des zones favorables - Republique de la Côte d'Ivoire]. Practica/Enterprise Works/VITA/UNICEF | ||
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United Nations. 1988. [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060034 Groundwater in North and West Africa: Côte d'Ivoire]. United Nations Department of Technical Cooperation for Development and Economic Commission for Africa, Natural Resources/Water Series No.18, ST/TCD/5 | United Nations. 1988. [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060034 Groundwater in North and West Africa: Côte d'Ivoire]. United Nations Department of Technical Cooperation for Development and Economic Commission for Africa, Natural Resources/Water Series No.18, ST/TCD/5 | ||
− | Return to the index pages | + | ==Return to the index pages== |
− | [[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] | + | [[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Cote d'Ivoire |