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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]  >> Hydrogeology of Djibouti
 
[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]  >> Hydrogeology of Djibouti
  
'''Lire cette page en français: [[Hydrogéologie de Djibouti | Hydrogéologie de Djibouti]]''' [[File: flag_of_france.png  | 50px]]
 
  
[[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]]]
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'''This page has limited information and needs to be updated. If you have more information on the hydrogeology of Djibouti, please get in touch'''
  
 
Djibouti, located where the Red Sea joins the Gulf of Aden and the Indian Ocean, at a crossroads linking Africa to the Middle East, and at the mouth of the Suez Canal, has always been a trading hub. The area of present-day Djibouti was once part of a series of ancient kingdoms with strong links to ancient Ethiopia and Egypt. Its proximity to the Arabian Peninsula meant Islam was adopted early. It was later colonised by France in the late 19th century, and the construction of railroads to Ethiopia meant it became an important regional port. It won independence as the Republic of Djibouti in 1977. The independent country’s first president remained in power until 1999. In the 1990s, the country experienced a civil war that ended in a power sharing agreement in 2000. Since 2000, there have been periodic episodes of civil unrest and a number of contested elections, but overall Djibouti is perceived internationally as having being relatively politically stable.  
 
Djibouti, located where the Red Sea joins the Gulf of Aden and the Indian Ocean, at a crossroads linking Africa to the Middle East, and at the mouth of the Suez Canal, has always been a trading hub. The area of present-day Djibouti was once part of a series of ancient kingdoms with strong links to ancient Ethiopia and Egypt. Its proximity to the Arabian Peninsula meant Islam was adopted early. It was later colonised by France in the late 19th century, and the construction of railroads to Ethiopia meant it became an important regional port. It won independence as the Republic of Djibouti in 1977. The independent country’s first president remained in power until 1999. In the 1990s, the country experienced a civil war that ended in a power sharing agreement in 2000. Since 2000, there have been periodic episodes of civil unrest and a number of contested elections, but overall Djibouti is perceived internationally as having being relatively politically stable.  
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The geology map shows a simplified version of the geology at a national scale. More information is available in the report [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060007 UN (1989)] (see References section, below).
 
The geology map shows a simplified version of the geology at a national scale. More information is available in the report [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=ViewDetails&id=AGLA060007 UN (1989)] (see References section, below).
 
[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Djibouti geology and hydrogeology map'''].
 
  
  
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| [[File:Djibouti_Geology3.png | center | thumb| 500px | Geology of Djibouti 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 Djibouti geology and hydrogeology map].]]
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| [[File:Djibouti_Geology.png | center | thumb| 500px | Geology of Djibouti 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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==Hydrogeology==
 
==Hydrogeology==
  
The hydrogeology map below shows a simplified version 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).
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The hydrogeology map below 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).  
 
 
[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Djibouti geology and hydrogeology map'''].
 
  
A more detailed overview of the hydrogeology of the main aquifers in Djibouti is in  [https://link.springer.com/article/10.1007%2Fs10040-003-0312-2 '''Jalludin and Razack (2004)'''].
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A more detailed overview of the hydrogeology of the main aquifers in Djibouti is in  [https://link.springer.com/article/10.1007%2Fs10040-003-0312-2 Jalludin and Razack (2004)].
  
[[File:Djibouti_Hydrogeology3.png| center | thumb| 500px | Hydrogeology of Djibouti 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 Djibouti geology and hydrogeology map].]]
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[[File:Djibouti_Hydrogeology.png| center | thumb| 500px | Hydrogeology of Djibouti at 1:5 million scale. For more information on how the map was developed see the [[Hydrogeology Map | hydrogeology map]] resource page]]
  
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[[File: Hydrogeology_Key.png | center| 500x195px]]
  
 
'''Summary'''
 
'''Summary'''
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{| class = "wikitable"
 
{| class = "wikitable"
|Aquifer||Aquifer Productivity||General Description
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|Aquifer||General Description
 
|-
 
|-
 
|Wadi (valley) alluvium aquifers
 
|Wadi (valley) alluvium aquifers
||Generally High to Very High (but Variable)
 
 
||Alluvial sediments deposited along the main wadis, forming narrow, elongate aquifers that vary from tens to several hundreds of metres in width and from a few meters to a few tens of meters in thickness  (Jalludin and Razack 2004). Usually unconfined. Jalludin and Razack (2004) quote summary statistics of transmissivity values from 38 constant rate pumping tests from unconsolidated sedimentary aquifers, although it is not known whether these are wadi or alluvial plain aquifers:  the transmissivity values ranged from 38 to 14,150 m<sup>2</sup>/day, with an average of 1490 m<sup>2</sup>/day.
 
||Alluvial sediments deposited along the main wadis, forming narrow, elongate aquifers that vary from tens to several hundreds of metres in width and from a few meters to a few tens of meters in thickness  (Jalludin and Razack 2004). Usually unconfined. Jalludin and Razack (2004) quote summary statistics of transmissivity values from 38 constant rate pumping tests from unconsolidated sedimentary aquifers, although it is not known whether these are wadi or alluvial plain aquifers:  the transmissivity values ranged from 38 to 14,150 m<sup>2</sup>/day, with an average of 1490 m<sup>2</sup>/day.
 
|-
 
|-
 
|Alluvial plain aquifers
 
|Alluvial plain aquifers
||Generally High to Very High (but Variable)
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||Alluvial plain aquifers, including coastal and inland basin aquifers, cover some 22 % of the country. The extent of individual aquifers varies between 40 km<sup>2</sup> and 1,500 km<sup>2</sup>, and the thickness of the alluvial sediments varies between 40 m and more than 300 m. Jalludin and Razack (2004) quote summary statistics of transmissivity values from 38 constant rate pumping tests from unconsolidated sedimentary aquifers, although it is not known whether these are wadi or alluvial plain aquifers: the transmissivity values ranged from 38 to 14,150 m<sup>2</sup>/day, with an average of 1490 m<sup>2</sup>/day.
||Alluvial plain aquifers, including coastal and inland basin aquifers, cover some 22 % of the country. The extent of individual aquifers varies between 40 km<sup>2</sup> and 1,500 km<sup>2</sup>, and the thickness of the alluvial sediments varies between 40 m and more than 300 m. Jalludin and Razack (2004) quote summary statistics of transmissivity values from 38 constant rate pumping tests from unconsolidated sedimentary aquifers, although it is not known whether these are wadi or alluvial plain aquifers: the transmissivity values ranged from 38 to 14,150 m<sup>2</sup>/day, with an average of 1490 m<sup>2</sup>/day.
 
  
 
Groundwater quality is generally poor, with 1 g/l to more than 2 g/l of total mineralisation (Jalludin and Razack 2004).
 
Groundwater quality is generally poor, with 1 g/l to more than 2 g/l of total mineralisation (Jalludin and Razack 2004).
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{| class = "wikitable"
 
{| class = "wikitable"
|Aquifer type||Named formations||Aquifer Productivity||General Description
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|Aquifer type||Named formations||General Description
 
|-
 
|-
|Regional scale stratiform volcanic aquifers - Quaternary  
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|Regional scale stratiform volcanic aquifers - Quaternary age
||Gulf and stratiform basalts; stratiform rhyolites  
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||Gulf and stratiform basalts; stratiform rhyolites.
||Generally High to Very High (but Variable)
 
 
||The stratiform basalt series covers an area of about 9000 km<sup>2</sup> in the southwestern and northwestern regions of the country, extending into Ethiopia, and can reach 1300 m thick. Groundwater flow is dominantly through fractures. Transmissivity values from 26 constant rate pumping tests ranged from 13 to 27,100 m<sup>2</sup>/day, with an average of 5350 m<sup>2</sup>/day; the average storage coefficient was 2 × 10<sup>−5</sup> (Jalludin and Razack 2004). Based on only 3 constant rate pumping tests, stratiform rhyolites show higher transmissivity values, from 4660 to 46,600 m<sup>2</sup>/day (Jalludin and Razack 2004).  
 
||The stratiform basalt series covers an area of about 9000 km<sup>2</sup> in the southwestern and northwestern regions of the country, extending into Ethiopia, and can reach 1300 m thick. Groundwater flow is dominantly through fractures. Transmissivity values from 26 constant rate pumping tests ranged from 13 to 27,100 m<sup>2</sup>/day, with an average of 5350 m<sup>2</sup>/day; the average storage coefficient was 2 × 10<sup>−5</sup> (Jalludin and Razack 2004). Based on only 3 constant rate pumping tests, stratiform rhyolites show higher transmissivity values, from 4660 to 46,600 m<sup>2</sup>/day (Jalludin and Razack 2004).  
  
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|-
 
|-
|Local scale volcanic aquifers, with minor interbedded volcaniclastic, alluvial sands, silts and clays, sometimes calcareous - Tertiary  
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|Local scale volcanic aquifers, with minor interbedded volcaniclastic, alluvial sands, silts and clays, sometimes calcareous - Tertiary age.
||Dalha and Somali basalts; Mabla rhyolites; Adolei basalts
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||Dalha and Somali basalts; Mabla rhyolites; Adolei basalts.
||Generally Moderate to Very High (but Variable)
 
 
||Volcanic aquifers of limited extent (area <2000 km<sup>2</sup>), including basalt traps (series of individual lava flows several metres thick, which in total can reach >200 m thick) (Jalludin and Razack 2004). Groundwater flow is dominantly through fractures.  
 
||Volcanic aquifers of limited extent (area <2000 km<sup>2</sup>), including basalt traps (series of individual lava flows several metres thick, which in total can reach >200 m thick) (Jalludin and Razack 2004). Groundwater flow is dominantly through fractures.  
  
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|}
 
|}
  
====Consolidated Sedimentary - Intergranular and Fracture Flow====
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====Consolidated sedimentary====
  
 
{| class = "wikitable"
 
{| class = "wikitable"
|Aquifer||Aquifer Productivity||General Description
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|Aquifer||General Description
 
|-
 
|-
 
|Jurassic-Cretaceous sandstones
 
|Jurassic-Cretaceous sandstones
||Probably Moderate to High
 
 
||These rocks have only a small outcrop in the southeast of the country, and little is known of their aquifer properties. Jalludin and Razack (2004) quote a single transmissivity value from a constant rate pumping test of 1800 m<sup>2</sup>/day.
 
||These rocks have only a small outcrop in the southeast of the country, and little is known of their aquifer properties. Jalludin and Razack (2004) quote a single transmissivity value from a constant rate pumping test of 1800 m<sup>2</sup>/day.
 
|}
 
|}
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===Groundwater quality===
 
===Groundwater quality===
  
Groundwater salinity is widely high: in 2005, more than half of Djibouti's boreholes were recorded as showing salinity of more than 900 mg/l, and sometimes up to 1,200 mg/l. At this time, only groundwater in the northwest of the country was recorded as having ionic levels below the standards of use for irrigation. High levels of boron are the most common (FAO AQUASTAT 2005). Where groundwater is used for agriculture, high evapotranspiration rates and mineralised irrigation returns have contributed to rising salinity, both in shallow alluvial and deeper volcanic rock aquifers. In coastal zones, salinity is exacerbated by over-abstraction that draws down water levels and induces sea water intrusion (Ahmed et al 2018).
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Groundwater salinity is widely high: in 2005, more than half of Djibouti's boreholes were recorded as showing salinity of more than 900 mg/l, and sometimes up to 1,200 mg/l. At this time, only groundwater in the northwest of the country was recorded as having ionic levels below the standards of use for irrigation. High levels of boron are the most common (FAO AQUASTAT 2005). Where groundwater is used for agriculture, high evapotranspiration rates and mineralised irrigation returns have contributed to rising salinity, both in shallow alluvial and deeper volcanic rock aquifers. In coastal zones, salinity is exacerbated by over-abstraction that draws down water levels and induces sea water intrusion(Ahmed et al. 2018).
  
 
Rapid urbanisation with a lack of adequate sanitation is contributing to groundwater quality degradation in urban areas (Ahmed et al 2017).
 
Rapid urbanisation with a lack of adequate sanitation is contributing to groundwater quality degradation in urban areas (Ahmed et al 2017).
  
Nitrate concentrations are high in many areas, in both alluvial and volcanic aquifers. Much of this is likely to be natural, reflecting evaporative and biochemical controls in arid conditions, but some is likely to be due to local contamination by livestock or human waste (Awaleh et al 2017).
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Nitrate concentrations are high in many areas, in both alluvial and volcanic aquifers. Much of this is likely to be natural, reflecting evaporative and biochemical controls in arid conditions, but some is likely to be due to local contamination by livestock or human waste (Awaleh et al 2017)
  
 
==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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Aboubaker M, Jalludin M and Razack M. 2013. [https://doi.org/10.1007/s12665-013-2398-8 Hydrochemistry of a complex volcano-sedimentary aquifer using major ions and environmental isotopes data: Dalha basalts aquifer, southwest of Republic of Djibouti]. Environmental Earth Sciences 70 (7), 3335–3349. doi 10.1007/s12665-013-2398-8
 
Aboubaker M, Jalludin M and Razack M. 2013. [https://doi.org/10.1007/s12665-013-2398-8 Hydrochemistry of a complex volcano-sedimentary aquifer using major ions and environmental isotopes data: Dalha basalts aquifer, southwest of Republic of Djibouti]. Environmental Earth Sciences 70 (7), 3335–3349. doi 10.1007/s12665-013-2398-8
  
Ahmed IM, Le Coz M, Jalludin M, Sardini P and Razack M. 2018. [https://doi.org/10.4236/jwarp.2018.101007  Assessment of Groundwater Resources in a Complex Volcanic Reservoir with Limited Data Sets in a Semi-Arid Context Using a Novel Stochastic Approach. The Goda Volcanic Massif, Republic of Djibouti]. Journal of Water Resource and Protection 10, 106-120. doi 10.4236/jwarp.2018.101007
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Ahmed IM, Le Coz M, Jalludin M, Sardini P and Razack M. 2018. [https://file.scirp.org/pdf/JWARP_2018013015200884.pdf Assessment of Groundwater Resources in a Complex Volcanic Reservoir with Limited Data Sets in a Semi-Arid Context Using a Novel Stochastic Approach. The Goda Volcanic Massif, Republic of Djibouti]. Journal of Water Resource and Protection 10, 106-120. doi 10.4236/jwarp.2018.101007
  
Ahmed AH, Rayaleh WE, Zghibi A and Ouaddane B. 2018. [https://doi.org/10.1016/j.jafrearsci.2017.04.010 Assessment of chemical quality of groundwater in coastal volcano-sedimentary aquifer of Djibouti, Horn of Africa]. Journal of African Earth Sciences 131, 284-300. doi 10.1016/j.jafrearsci.2017.04.010
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Ahmed AH, Rayaleh WE, Zghibi A and Ouaddane B. 2018. [https://www.sciencedirect.com/science/article/pii/S1464343X1730153X Assessment of chemical quality of groundwater in coastal volcano-sedimentary aquifer of Djibouti, Horn of Africa]. Journal of African Earth Sciences 131, 284-300. doi 10.1016/j.jafrearsci.2017.04.010
  
 
AQUATER-ISERST. 1986. Préfactibilité géothermique de la plaine de Hanlé-Gaggadé [Geothermic feasibility study of the plain of Hanlé-Gaggadé]. Report.
 
AQUATER-ISERST. 1986. Préfactibilité géothermique de la plaine de Hanlé-Gaggadé [Geothermic feasibility study of the plain of Hanlé-Gaggadé]. Report.
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ISERST. 1985–1995. Cartes géologiques de la République de Djibouti à 1/100000 [Geological maps of the Republic of Djibouti at 1/100000]. Editions ORSTOM, Paris, France
 
ISERST. 1985–1995. Cartes géologiques de la République de Djibouti à 1/100000 [Geological maps of the Republic of Djibouti at 1/100000]. Editions ORSTOM, Paris, France
  
Jalludin M and Razack M. 1994. [https://doi.org/10.1016/0022-1694(94)90167-8 Analysis of pumping tests in fractured basalts with regards to tectonics, hydrothermal effects and weathering, Republic of Djibouti]. Journal of Hydrology, 155, 237-250. doi 10.1016/0022-1694(94)90167-8.
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Jalludin M and Razack M. 1994. [https://www.sciencedirect.com/science/article/pii/0022169494901678?via%3Dihub Analysis of pumping tests in fractured basalts with regards to tectonics, hydrothermal effects and weathering, Republic of Djibouti]. Journal of Hydrology, 155, 237-250. doi 10.1016/0022-1694(94)90167-8.
  
Jalludin M and Razack M. 2004. [https://doi.org/10.1007/s10040-003-0312-2 Assessment of hydraulic properties of sedimentary and volcanic aquifer systems under arid conditions in the Republic of Djibouti (Horn of Africa)].  
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Jalludin M and Razack M. 2004. [https://link.springer.com/article/10.1007%2Fs10040-003-0312-2 Assessment of hydraulic properties of sedimentary and volcanic aquifer systems under arid conditions in the Republic of Djibouti (Horn of Africa)].  
 
Hydrogeology Journal, 12, 159-170. doi 10.1007/s10040-003-0312-2.  
 
Hydrogeology Journal, 12, 159-170. doi 10.1007/s10040-003-0312-2.  
  
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==Return to the index pages==
[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]   
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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]  >> Hydrogeology of Djibouti
  
 
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