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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Tunisia
 
[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Tunisia
 
  '''Lire cette page en français: [[Hydrogéologie de la Tunisie | Hydrogéologie de la Tunisie]]''' [[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]]]
 
 
Tunisia was historically inhabited by Berbers, becoming the seat of Carthage and later part of the Roman empire. Arab dynasties ruled between the 8th and 13th centuries, followed by the Ottomans from the 16th to the 19th century and then by French colonisation until independence in 1957. It had a relatively stable democracy until civil unrest in 2011, which saw a change in government, and an a return to more stable conditions. 
 
 
Tunisia’s economy is dominated by the service sector (accounting for over 60% of GDP), including tourism. Petroleum products account for over 11% of exports. Other inmportant sectors are industry (25% of GDP) agriculture (around 11% of GDP) and mining.
 
 
Tunisia has the highest access rates to water supply and sanitation in the Middle East and North Africa. Access to safe drinking water became close to universal, approaching 100% in urban areas and 94% in rural areas. With its semi-arid to arid climate, surface water resources are scarce in the south of the country, but the northern coastal region has relatively abundant rainfall and surface water resources .  Groundwater is the main source of water – both shallow renewable and deep, often non-renewable groundwater. Over 75% of groundwater is used by agriculture; most of the rest is for domestic supply. Uncontrolled over-abstraction of groundwater, largely for irrigation by small farmers, is causing over-exploitation of aquifers in some areas.
 
 
 
  
 
==Authors==
 
==Authors==
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'''Kirsty Upton''' & '''Brighid Ó Dochartaigh''', British Geological Survey, UK
 
'''Kirsty Upton''' & '''Brighid Ó Dochartaigh''', British Geological Survey, UK
  
'''Imogen Bellwood-Howard''', Institute of Development Studies, UK
 
 
Please cite this page as: Ben Ammar, Mekni, Upton, Ó Dochartaigh and Bellwood-Howard, 2018.
 
 
Bibliographic reference: Ben Ammar, S., Mekni, A., Upton, K., Ó Dochartaigh, B.É. and Bellwood-Howard, I. 2018. Africa Groundwater Atlas: Hydrogeology of Tunisia. British Geological Survey. Accessed [date you accessed the information]. http://earthwise.bgs.ac.uk/index.php/Hydrogeology_of_Tunisia
 
 
==Terms and conditions==
 
 
The Africa Groundwater Atlas is hosted by the British Geological Survey (BGS) and includes information from third party sources. Your use of information provided by this website is at your own risk. If reproducing diagrams that include third party information, please cite both the Africa Groundwater Atlas and the third party sources. Please see the [[Africa Groundwater Atlas Terms of Use | Terms of use]] for more information.
 
  
 
==Geographical Setting==
 
==Geographical Setting==
  
[[File: Tunisia_Political.png | right | frame | Tunisia. 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: Tunisia_Political.png | right | frame | Map of Tunisia (For more information on the datasets used in the map see the [[Geography | geography resources section]])]]  
  
 
===General===
 
===General===
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{| class = "wikitable"
 
{| class = "wikitable"
 
|-
 
|-
|Capital city || Tunis
+
|Estimated Population in 2013* || 10,886,500
 
|-
 
|-
|Region || Northern Africa
+
|Rural Population (% of total) (2013)* || 33.5%
 
|-
 
|-
|Border countries || Algeria, Libya
+
|Total Surface Area* || 155,360 sq km
 
|-
 
|-
|Total surface area* ||163,610 km<sup>2</sup>  (16,361,000 ha)
+
|Agricultural Land (% of total area) (2012)* || 64.9%
 
|-
 
|-
|Total population (2015)* || 11,254,000
+
|Capital City || Tunis
 
|-
 
|-
|Rural population (2015)* ||3,744,000 (33%)
+
|Region || Northern Africa
 
|-
 
|-
|Urban population (2015)* ||7,510,000 (67%)
+
|Border Countries || Algeria, Libya
 
|-
 
|-
|UN Human Development Index (HDI) [highest = 1] (2014)*|| 0.721
+
|Annual Freshwater Withdrawal (2013)* || 2850 Million cubic metres
 +
|-
 +
|Annual Freshwater Withdrawal for Agriculture (2013)* || 76.0%
 +
|-
 +
|Annual Freshwater Withdrawal for Domestic Use (2013)* || 12.8%
 +
|-
 +
|Annual Freshwater Withdrawal for Industry (2013)* || 3.9%
 +
|-
 +
|Rural Population with Access to Improved Water Source (2012)* || 90.5%
 +
|-
 +
|Urban Population with Access to Improved Water Source (2012)* || 100%
 
|}
 
|}
  
<nowiki>*</nowiki> Source: [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en FAO Aquastat]
+
<nowiki>*</nowiki> Source: World Bank
 +
 
  
 
===Climate===
 
===Climate===
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to 300 mm/year) and becoming very light in the south (less than 150 mm/year and less than 50 mm/year in the far south), with some years of no rain.  
 
to 300 mm/year) and becoming very light in the south (less than 150 mm/year and less than 50 mm/year in the far south), with some years of no rain.  
  
[[File: Tunisia_ClimateZones.png | 375x365px |Koppen Geiger Climate Zones]][[File: Tunisia_ClimatePrecip.png | 375x365px |Average Annual Precipitation]][[File: Tunisia_ClimateTemp.png | 375x365px |Average Temperature]]
+
<gallery widths="375px" heights=365px mode=nolines>
 +
File: Tunisia_ClimateZones.png |Koppen Geiger Climate Zones
 +
File: Tunisia_ClimatePrecip.png |Average Annual Precipitation
 +
File: Tunisia_ClimateTemp.png |Average Temperature
 +
</gallery>
  
[[File: Tunisia_pre_Monthly.png| 255x124px| Average monthly precipitation for Tunisia showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File: Tunisia_tmp_Monthly.png| 255x124px| Average monthly temperature for Tunisia showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File: Tunisia_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File: Tunisia_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 Tunisia can be seen at the [[Climate of Tunisia | Tunisia climate page]].
+
[[File: Tunisia_pre_Monthly.png| 255x124px| Average monthly precipitation for Tunisia showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File: Tunisia_tmp_Monthly.png| 255x124px| Average monthly temperature for Tunisia showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File: Tunisia_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File: Tunisia_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]].
+
For further detail on the climate datasets used see the [[Climate | climate resources section]].
  
 
===Surface water===
 
===Surface water===
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| [[File: Tunisia_Hydrology.png | frame | Major surface water features of Tunisia. Map developed from World Wildlife Fund HydroSHEDS; Digital Chart of the World drainage; and FAO Inland Water Bodies. For more information on the map development and datasets see the [[Surface water | surface water resource page]].]]
+
| [[File: Tunisia_Hydrology.png | frame | Surface Water Map of Tunisia (For more information on the datasets used in the map see the [[Surface water | surface water resources section]])]]
 
 
|
 
 
|}
 
|}
  
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| [[File: Tunisia_soil.png | frame | Soil Map of Tunisia, from the European Commission Joint Research Centre: European Soil Portal. For more information on the map see the [[Soil | soil resource page]].]]
+
| [[File: Tunisia_soil.png | frame | Soil Map of Tunisia (For map key and more information on the datasets used in the map see the [[Soil | soil resources section]])]]
|
+
 
 
|}
 
|}
  
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| [[File: Tunisia_LandCover.png | frame | Land Cover Map of Tunisia, from the European Space Agency GlobCover 2.3, 2009. For more information on the map see the [[Land cover | land cover resource page]].]]
+
| [[File: Tunisia_LandCover.png | frame | Land Cover Map of Tunisia (For map key and more information on the datasets used in the map see the [[Land cover | land cover resources section]])]]
 
 
|
 
|}
 
 
 
===Water statistics===
 
 
 
{| class = "wikitable"
 
| || 2000 ||2006||2011||2012||2014||2015
 
|-
 
|Rural population with access to safe drinking water (%) || || ||  || || ||93.2
 
|-
 
|Urban population with access to safe drinking water (%) || || ||  || || ||100
 
|-
 
|Population affected by water related disease ||No data || No data || No data  || No data || No data ||No data
 
|-
 
|Total internal renewable water resources (cubic metres/inhabitant/year) || || ||  || ||372.8 ||
 
|-
 
|Total exploitable water resources (Million cubic metres/year) || || || ||3,625|| ||
 
|-
 
|Freshwater withdrawal as % of total renewable water resources || || ||69.71 || || ||
 
|-
 
|Total renewable groundwater (Million cubic metres/year) ||  || || || ||1,595 ||
 
|-
 
|Exploitable: Regular renewable groundwater (Million cubic metres/year) || || ||  ||1,150 || ||
 
|-
 
|Groundwater produced internally (Million cubic metres/year) || || ||  || ||1,495 ||
 
|-
 
|Fresh groundwater withdrawal (primary and secondary) (Million cubic metres/year) |||| ||2,066 || || ||
 
|-
 
|Groundwater: entering the country (total) (Million cubic metres/year) || || ||  || ||100 ||
 
|-
 
|Groundwater: leaving the country to other countries (total) (Million cubic metres/year) || || ||0 || || ||
 
|-
 
|Industrial water withdrawal (all water sources) (Million cubic metres/year) || || || 165|| || ||
 
|-
 
| Municipal water withdrawal (all water sources) (Million cubic metres/year)  || || ||496 || || ||
 
|-
 
|Agricultural water withdrawal (all water sources) (Million cubic metres/year) || || ||2,644 || || ||
 
|-
 
|Irrigation water withdrawal (all water sources)<sup>1</sup> (Million cubic metres/year) ||No data || No data || No data  || No data || No data ||No data
 
|-
 
|Irrigation water requirement (all water sources)<sup>1</sup> (Million cubic metres/year) ||1,552 || ||  || || ||
 
|-
 
|Area of permanent crops (ha) || || ||  || ||2,330,000 ||
 
|-
 
|Cultivated land (arable and permanent crops) (ha) || || ||  || ||5,232,000 ||
 
|-
 
|Total area of country cultivated (%) || || ||  || ||31.98 ||
 
|-
 
|Area equipped for irrigation by groundwater (ha) || ||271,800||  || || ||
 
|-
 
|Area equipped for irrigation by mixed surface water and groundwater (ha) ||13,000 || ||  || || ||
 
 
|}
 
|}
 
These statistics are sourced from [http://www.fao.org/nr/water/aquastat/main/index.stm FAO Aquastat]. 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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This section provides a summary of the geology of Tunisia. More detail can be found in the references listed at the bottom of this page. Many of these references can be accessed through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].
 
This section provides a summary of the geology of Tunisia. More detail can be found in the references listed at the bottom of this page. Many of these references can be accessed through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].
  
The geology map on this page shows a simplified overview of the geology at a national scale (see the [[Geology | Geology resource page]] for more details).
+
The geology map on this page shows a simplified version of the geology at a national scale (see [[Geology | the Geology resources page]] for more details).  
 
 
[https://www.bgs.ac.uk/africagroundwateratlas/downloadGIS.html '''Download a GIS shapefile of the Tunisia geology and hydrogeology map'''].
 
  
 
More detailed geological maps are published by the Service Geologique de Tunisie (at 1:500,000 scale) and the National Office of Mines (ONM) (at 1:50,000 and 1:100,000 scale) (see Geology: Key References, below).
 
More detailed geological maps are published by the Service Geologique de Tunisie (at 1:500,000 scale) and the National Office of Mines (ONM) (at 1:50,000 and 1:100,000 scale) (see Geology: Key References, below).
  
[[File:Tunisia_Geology4.png | center | thumb| 500px | Geology of Tunisia 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 Tunisia geology and hydrogeology map].]]
+
[[File: Tunisia_Geology2.png | center | 300px]]
  
'''Summary'''
+
===Summary===
  
 
The north of Tunisia has been extensively affected by tectonic movements, with anticlines and synclines generally trending southwest - northeast, and a series of faults.  
 
The north of Tunisia has been extensively affected by tectonic movements, with anticlines and synclines generally trending southwest - northeast, and a series of faults.  
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|Key Formations||Period||Lithology
 
|Key Formations||Period||Lithology
 
|-
 
|-
!colspan="4"|Unconsolidated Sediments
+
!colspan="4"|Unconsolidated
 
|-
 
|-
 
|Alluvial plains, including Ghardimou,Kalaa Khasba, Oued Guinniche basin (northern Tunisia) and Kairouan and Sfax basins (central Tunisia)
 
|Alluvial plains, including Ghardimou,Kalaa Khasba, Oued Guinniche basin (northern Tunisia) and Kairouan and Sfax basins (central Tunisia)
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|-
 
|-
 
|Series of marine and continental formations
 
|Series of marine and continental formations
||Cretaceous - Tertiary - general
+
||Cretaceous - Tertiary
||Cretaceous and Tertiary sedimentary formations occur across most of Tunisia. Across the centre and north of the country are many different marine and continental sedimentary formations.  
+
||Cretaceous and Tertiary sedimentary formations occur across most of Tunisia. In the south, the two largest formations are the Complex Terminal and Continental Intercalaire (see below). Across the centre and north of the country are many othe rsmaller marine and continental sedimentary formations.  
  
 
Continental sandstones occur in major sedimentary basins across much of central Tunisia, sometimes directly underlying Quaternary unconsolidated alluvium, such as in the Sfax basin and the Pliocene-Quaternary Kairouan basin. Small outcrops of limestone formations, sometimes with marls, dolostones, gypsum and other evaporates, are scattered across northern and central Tunisia, often interbedded with sand formation.
 
Continental sandstones occur in major sedimentary basins across much of central Tunisia, sometimes directly underlying Quaternary unconsolidated alluvium, such as in the Sfax basin and the Pliocene-Quaternary Kairouan basin. Small outcrops of limestone formations, sometimes with marls, dolostones, gypsum and other evaporates, are scattered across northern and central Tunisia, often interbedded with sand formation.
 +
 
|-
 
|-
 
|Complex Terminal (CT)
 
|Complex Terminal (CT)
 
||Upper Cretaceous - Tertiary
 
||Upper Cretaceous - Tertiary
||The Complex Terminal is one of the two main formations in the south of Tunisia (the other is the Continental Intercalaire, below). It comprises Upper Cretaceous (Senonian and Turonian) carbonate rocks; and Tertiary (Mio-Pliocene) detrital sand formations.
+
||Upper Cretaceous (Senonian and Turonian) carbonate rocks; and Tertiary (Mio-Pliocene) detrital sand formations.
  
 
|-
 
|-
 
|Continental Intercalaire (CI)
 
|Continental Intercalaire (CI)
 
||Lower Cretaceous
 
||Lower Cretaceous
||The Continental Intercalaire is one of the two main formations in the south of Tunisia (the other is the Complex Terminal, above). It comprises a continental facies of sands, limestones and clays.  
+
||A continental facies of sands, limestones and clays.  
  
 
|-
 
|-
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This section provides a summary of the hydrogeology of the main aquifers in Tunisia.  More information is available in the references listed at the bottom of this page. Many of these references can be accessed through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].
 
This section provides a summary of the hydrogeology of the main aquifers in Tunisia.  More information is available in the references listed at the bottom of this page. Many of these references can be accessed through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].
  
The hydrogeology map on this page 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 on this page 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 Tunisia geology and hydrogeology map'''].
 
  
 
A more detailed hydrogeological map at 1:500,000 scale is published by the DGRE (Zebidi 1991), and a different simplified map is published by SEMIDE (see Hydrogeology: Key References, below).
 
A more detailed hydrogeological map at 1:500,000 scale is published by the DGRE (Zebidi 1991), and a different simplified map is published by SEMIDE (see Hydrogeology: Key References, below).
  
[[File:Tunisia_Hydrogeology4.png | center | thumb| 500px | Hydrogeology of Tunisia 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 Tunisia geology and hydrogeology map].]].
+
[[File:Tunisia_Hydrogeology2.png | center| 300px]]
  
  
'''Summary'''
+
===Summary===
  
 
Aquifers in Tunisia are classified according to whether they are:
 
Aquifers in Tunisia are classified according to whether they are:
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'''Deep aquifers''' - more than 50 m deep.
 
'''Deep aquifers''' - more than 50 m deep.
  
In the following summary and in the hydrogeology map above, most of the aquifers are classified as dominantly unconsolidated, in which groundwater flow and storage is entirely intergranular. The Complex Terminal and Continental Intercalaire aquifers - the principal aquifers in southern Tunisia - are treated separately; these aquifers have a mix of intergranular and fracture flow.  
+
In the following summary and in the hydrogeology map above, the aquifers are classified by their hydrogeological environment and the way that groundwater flow and storage occur: either unconsolidated, in which groundwater flow and storage is entirely intergranular; or, in consolidated aquifers, a mixture of intergranular and fracture flow.  
  
  
====Unconsolidated Aquifers====
+
====Unconsolidated====
 
{| class = "wikitable"
 
{| class = "wikitable"
 
|Named Aquifers||General Description||Water quantity issues||Water quality issues||Recharge
 
|Named Aquifers||General Description||Water quantity issues||Water quality issues||Recharge
 +
|-
 +
|Continental Intercalaire (CI) (Lower Cretaceous)
 +
||The Continental Intercalaire (CI) aquifer in southern Tunisia is of Lower Cretaceous age (Neocomian, Barremian, Aptian and Albian). It comprises detrital and continental formations, between 125 and 150 m thick, which are buried at depths of 1500 to at least 2400 m. The aquifer is confined, and piezometric water levels range from 500 to 3500 m depth.
 +
 +
Aquifer transmissivity values range from 0.8 to 170 x 10<sup>-3</sup>. Storativity values range from 0.2 to 1.4 x 10<sup>-4</sup>.
 +
||Annual abstraction from the CI aquifer in 2000 was 83.1 million cubic metres (Mm³).
 +
||Total dissolved solids in groundwater in the CI aquifer aquifer are between 1.5 and 4 g/l.
 +
||Recharge to the aquifer comes from the Algerian Atlas mountains. 
 +
 
|-
 
|-
 
|Sfax basin (Tertiary)
 
|Sfax basin (Tertiary)
 
||The Sfax basin in the east of the country is a sand sequence and forms an important coastal aquifer system, of Tertiary (Upper Miocene) age. The aquifer sequence is between 50 and 90 m thick, and it is buried at depths of between 200 to 600 m. The aquifer is confined. Piezometric water levels are 200 to 600 m deep. Boreholes abstracting from the aquifer are typically between 190 and 600 m deep.  
 
||The Sfax basin in the east of the country is a sand sequence and forms an important coastal aquifer system, of Tertiary (Upper Miocene) age. The aquifer sequence is between 50 and 90 m thick, and it is buried at depths of between 200 to 600 m. The aquifer is confined. Piezometric water levels are 200 to 600 m deep. Boreholes abstracting from the aquifer are typically between 190 and 600 m deep.  
  
Transmissivity values for the aquifer range from 0.1 to 7.3 x 10<sup>-2</sup> m<sup>2</sup>/sec. Storativity values range from 0.7 to 1.8 x 10<sup>-4</sup>.
+
Transmissivity values for the aquifer range from 0.1 to 7.3 x 10<sup>-2</sup>. Storativity values range from 0.7 to 1.8 x 10<sup>-4</sup>.
 
||Annual abstraction from the Sfax basin aquifer in 2000 was 19.16 million cubic metres (Mm³), from a total of 41 boreholes. Of this, abstraction for industrial use was 13.25 Mm³; for agriculture was 4.57 Mm³; and for domestic use was 1.34 Mm³.  
 
||Annual abstraction from the Sfax basin aquifer in 2000 was 19.16 million cubic metres (Mm³), from a total of 41 boreholes. Of this, abstraction for industrial use was 13.25 Mm³; for agriculture was 4.57 Mm³; and for domestic use was 1.34 Mm³.  
 
||Total dissolved solids in groundwater in the Sfax basin aquifer range from 2.5 to 10.5 g/l.  
 
||Total dissolved solids in groundwater in the Sfax basin aquifer range from 2.5 to 10.5 g/l.  
 
||There is recent recharge to the aquifer in the upstream region. In the downstream region, stable isotope and radiocarbon data have shown that there is no active recharge.
 
||There is recent recharge to the aquifer in the upstream region. In the downstream region, stable isotope and radiocarbon data have shown that there is no active recharge.
 +
 
|-
 
|-
 
|Kairouan plain (Tertiary - Quaternary)
 
|Kairouan plain (Tertiary - Quaternary)
 
||This is the most important aquifer system in central Tunisia, formed of detrital alluvial sediments of Plio-Quaternary age, which can be more than 700 m thick. The aquifer is unconfined and the water table depth ranges from 1 to 700 m. The aquifer is exploited both by large diameter dug wells only a few metres deep, and by boreholes that can be more than 700 m deep; the mean borehole depth is between 100 and 250 m.  
 
||This is the most important aquifer system in central Tunisia, formed of detrital alluvial sediments of Plio-Quaternary age, which can be more than 700 m thick. The aquifer is unconfined and the water table depth ranges from 1 to 700 m. The aquifer is exploited both by large diameter dug wells only a few metres deep, and by boreholes that can be more than 700 m deep; the mean borehole depth is between 100 and 250 m.  
  
Transmissivity values for the aquifer range from 4.8 x 10<sup>-4</sup> to 2.3 x 10<sup>-2</sup> m<sup>2</sup>/sec. Storativity values range from 1.5 x 10<sup>-4</sup> to 1 x 10<sup>-3</sup>.
+
Transmissivity values for the aquifer range from 4.8 x 10<sup>-4</sup> to 2.3 x 10<sup>-2</sup>. Storativity values range from 1.5 x 10<sup>-4</sup> to 1 x 10<sup>-3</sup>.
 
||Annual abstraction from the aquifer in 2000 was 53.5 million cubic metres (Mm³). Of this, 26 Mm³ was from a total of 118 boreholes, and 27.5 Mm³ was from a total of 4000 wells.  
 
||Annual abstraction from the aquifer in 2000 was 53.5 million cubic metres (Mm³). Of this, 26 Mm³ was from a total of 118 boreholes, and 27.5 Mm³ was from a total of 4000 wells.  
 
||Total dissolved solids in groundwater from the aquifer range from 1 to 3 g/l.  
 
||Total dissolved solids in groundwater from the aquifer range from 1 to 3 g/l.  
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||This is one of the most important aquifers in northeastern Tunisia. It is a multi-layered aquifer system, formed of heterogeneous alluvial deposits of Plio-Quaternary age. The aquifer is typically 100 to 200 m thick in total. There is an upper aquifer layer, which is unconfined, with a water table depth of less than 50 m; and a deeper layer, with a piezometric water level of 200 to 300 m depth. Boreholes abstracting from the aquifer are between 50 and 300 m deep.
 
||This is one of the most important aquifers in northeastern Tunisia. It is a multi-layered aquifer system, formed of heterogeneous alluvial deposits of Plio-Quaternary age. The aquifer is typically 100 to 200 m thick in total. There is an upper aquifer layer, which is unconfined, with a water table depth of less than 50 m; and a deeper layer, with a piezometric water level of 200 to 300 m depth. Boreholes abstracting from the aquifer are between 50 and 300 m deep.
  
Transmissivity values range from 3.1 to 130 x 10<sup>-5</sup> m<sup>2</sup>/sec. The mean storativity value is 5.5.  
+
Transmissivity values range from 3.1 to 130 x 10<sup>-5</sup>. The mean storativity value is 5.5.  
 
||Annual abstraction from a total of 233 boreholes is on the order of 8 million cubic metres (Mm³) (data from 2012) and from a total of 1540 wells is 11 million cubic metres (Mm³) (data from 2008).  
 
||Annual abstraction from a total of 233 boreholes is on the order of 8 million cubic metres (Mm³) (data from 2012) and from a total of 1540 wells is 11 million cubic metres (Mm³) (data from 2008).  
 
||Total dissolved solids in groundwater from the aquifer range from 0.3 to 4 g/l.  
 
||Total dissolved solids in groundwater from the aquifer range from 0.3 to 4 g/l.  
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||
 
||
 
||
 
||
 +
 +
 +
 
|}
 
|}
  
Line 328: Line 271:
 
Maliki MA (2000); Maliki et al. (2000); Nazoumou (2002); Ben Ammar (2007); Ben Ammar et al. (2009); Leduc et al. (2007); Ben Ammar et al. (2006); Jeribi (2004).
 
Maliki MA (2000); Maliki et al. (2000); Nazoumou (2002); Ben Ammar (2007); Ben Ammar et al. (2009); Leduc et al. (2007); Ben Ammar et al. (2006); Jeribi (2004).
  
 
+
==== Sedimentary - Intergranular & Fracture Flow====
====Complex Terminal and Continental Intercalaire (Sedimentary - Intergranular (including unconsolidated) & Mixed Intergranular/Fracture Flow)====
 
 
{| class = "wikitable"
 
{| class = "wikitable"
 
|Named Aquifers||General Description||Water quantity issues||Water quality issues||Recharge
 
|Named Aquifers||General Description||Water quantity issues||Water quality issues||Recharge
Line 341: Line 283:
 
||Total dissolved solids in groundwater from the CT aquifer are between 0.7 and 7 g/l.  
 
||Total dissolved solids in groundwater from the CT aquifer are between 0.7 and 7 g/l.  
 
||Recharge to the aquifer comes from the Algerian Atlas mountains; from the Dahar uplands in southeast Tunisia; and from mountains in the northern part of the Chott.  
 
||Recharge to the aquifer comes from the Algerian Atlas mountains; from the Dahar uplands in southeast Tunisia; and from mountains in the northern part of the Chott.  
|-
 
|Continental Intercalaire (CI) (Lower Cretaceous)
 
||The Continental Intercalaire (CI) aquifer in southern Tunisia is of Lower Cretaceous age (Neocomian, Barremian, Aptian and Albian). It comprises detrital and continental formations, between 125 and 150 m thick, which are buried at depths of 1500 to at least 2400 m. The aquifer is confined, and piezometric water levels range from 500 to 3500 m depth.
 
 
Aquifer transmissivity values range from 0.8 to 170 x 10<sup>-3</sup> m<sup>2</sup>/sec. Storativity values range from 0.2 to 1.4 x 10<sup>-4</sup>.
 
||Annual abstraction from the CI aquifer in 2000 was 83.1 million cubic metres (Mm³).
 
||Total dissolved solids in groundwater in the CI aquifer aquifer are between 1.5 and 4 g/l.
 
||Recharge to the aquifer comes from the Algerian Atlas mountains. 
 
|-
 
 
|}
 
|}
  
Line 363: Line 296:
 
===Groundwater quantity===
 
===Groundwater quantity===
  
The total water resources in Tunisia are estimated (by DGRE) at 4,825 million cubic metres (Mm³), of which 2,125 Mm³ are groundwater. Of this volume, there is an estimated 745 Mm³ of groundwater stored in phreatic (unconfined) aquifers (55% in the north of the country; 30% in the centre; and 15% in the south). Some 1,380 Mm³ of groundwater is stored in deep (confined) aquifers, of which only some 650 Mm³ is renewable (18% in the north; 24% in the centre; and 58% in the south).  
+
The total water resources in Tunisia are estimated (by DGRE) at 4825 million cubic metres (Mm³), of which 2125 Mm³ are groundwater. Of this volume, there is an estimated 745 Mm³ of groundwater stored in phreatic (unconfined) aquifers (55% in the north of the country; 30% in the centre; and 15% in the south). Some 1380 Mm³ of groundwater is stored in deep (confined) aquifers, of which only some 650 Mm³ is renewable (18% in the north; 24% in the centre; and 58% in the south).  
  
Abstraction from phreatic aquifers in 2000 was estimated at 780 Mm³, from 90,000 wells. This is equivalent to 105% of the estimated total storage in phreatic aquifers. Abstraction from deep aquifers in 2000 was estimated at 1,100 Mm³, from 3,500 boreholes. This is equivalent to 80% of the estimated total storage in deep aquifers.  
+
Abstraction from phreatic aquifers in 2000 was estimated at 780 Mm³, from 90000 wells. This is equivalent to 105% of the estimated total storage in phreatic aquifers. Abstraction from deep aquifers in 2000 was estimated at 1100 Mm³, from 3500 boreholes. This is equivalent to 80% of the estimated total storage in deep aquifers.  
  
 
The DGRE publishes an annual report on the exploitation of deep aquifers; and a report every 5 years on the exploitation of phreatic aquifers.
 
The DGRE publishes an annual report on the exploitation of deep aquifers; and a report every 5 years on the exploitation of phreatic aquifers.
Line 371: Line 304:
 
===Groundwater quality===
 
===Groundwater quality===
  
Salinisation of groundwater is widespread in Tunisia, linked to intensive exploitation; to the geochemical nature of geological deposits; and sometimes to leaching of irrigation water. Salinity generally increases towards the south and in older (fossil) groundwater: much of the groundwater in the south and parts of the centre of the country has total dissolved solids (TDS) of more than 3 g/l; and in much of the centre and north groundwater TDS is typically between 1.5 and 3 g/l. Saline intrusion in the coastal aquifers is also problematic.
+
Salinisation of groundwater is widespread in Tunisia, linked to intensive exploitation; to the geochemical nature of geological deposits; and sometimes to leaching of irrigation water. Salinity generally increases towards the south and in older (fossil) groundwater: much of the groundwater in the south and parts of the centre of the country has total dissolved solids (TDS) of more than 3 g/l; and in much of the centre and north groundwater TDS is typically between 1.5 and 3 g/l.  
 +
  
 
==Groundwater use and management==
 
==Groundwater use and management==
Line 381: Line 315:
 
Groundwater use by sector in Tunisia in 2000 was as follows (data from DGRE):  
 
Groundwater use by sector in Tunisia in 2000 was as follows (data from DGRE):  
  
* Agriculture 76.9%
+
Agriculture 76.9%
* Domestic 16.2 %
 
* Industry 6.4%
 
* Tourism 0.4%
 
  
Irrigation in Tunisia uses 2.14 billion m³/year (data from 2012), of which 74% comes from groundwater. Much irrigation is based on a system of family farms using thousands of shallow wells, many of which are uncontrolled by the Ministry of Agriculture. This is leading to aquifer over-exploitation, especially as wells and boreholes are increasingly converted to use electric pumps.
+
Domestic 16.2 %
  
The Tunisian government portal of the Euro-Mediterranean information system on know-how in the water sector ([http://www.semide.tn/ SEMIDE]) gives the following estimate of Tunisia’s groundwater potential and abstraction rate:
+
Industry 6.4%
 +
 
 +
Tourism 0.4%
 +
 
 +
 
 +
Irrigation in Tunisia uses 2.14 billion m³/year (data from 2012), of which 74% comes from groundwater. Much irrigation is based on a system of family farms using thousands of shallow wells, many of which are uncontrolled by the Ministry of Agriculture. This is leading to aquifer over-exploitation, especially as wells and boreholes are increasingly converted to use electric pumps.
  
{| class="wikitable"
 
|-
 
!
 
!Total groundwater resource (millions m<sup>3</sup>)
 
!Volume that can be used (millions m<sup>3</sup>/year)
 
! Groundwater abstraction (millions m<sup>3</sup>/year)
 
!Ratio of abstraction to total resource (%)
 
|-
 
|Shallow aquifers
 
|745
 
|745
 
|780
 
|105
 
|-
 
|Deep aquifers
 
|1380
 
|1380
 
|1100
 
|80
 
|-
 
|Total
 
|4825
 
|4295
 
|3680
 
|86
 
|}
 
  
 
===Groundwater management===
 
===Groundwater management===
  
Tunisia has invested heavily in monitoring, mobilizing and managing groundwater resources. Four water master plan have been successively put in place since the 1960s. The key institutions involved in groundwater management are:  
+
Tunisia has invested heavily in monitoring, mobilizing and managing groundwater resources. The key institutions involved in groundwater management are:  
  
The '''Direction Générale des Ressources en Eau (DGRE)''' / General Direction of Water Resources. This institution has a representation in all 24 departments in the country.
+
The Direction Générale des Ressources en Eau (DGRE)/General Direction of Water Resources. This institution has a representation in all 24 departments in the country.
  
The '''Société National d’Exploitation et de Distribution des Eaux (SONEDE)''' / National Water Distribution Utility (www.sonede.com.tn). This institution has resposibility for exploiting and distributing domestic water supplies.
+
The Société National d’Exploitation et de Distribution des Eaux (SONEDE)/ National Water Distribution Utility (www.sonede.com.tn). This institution has resposibility for exploiting and distributing domestic water supplies.
  
The legal framework for groundwater management falls under the Law No. 16-75 of 31 March 1975 on the promulgation of the Water Code. A [http://www.semide.tn/CDE072014.pd revised version of the Law] is under preparation.
 
  
A permit from the DGRE is required for drilling any borehole or well exceeding 50 m in depth. Private abstraction from shallow aquifers less than 50 m deep is not regulated, and as a result, many are over-exploited.
+
The legal framework for groundwater management falls under the Law No. 16-75 of 31 March 1975 on the promulgation of the Water Code. A new revised version of the Law is under preparation (http://www.semide.tn/CDE072014.pd).
 +
 
 +
A permit from the DGRE is required for drilling any borehole or well exceeding 50 m in depth.  
  
 
Some river basins suffering from overexploitation or/and pollution are protected, and no drilling permit is allowed in these basins.  
 
Some river basins suffering from overexploitation or/and pollution are protected, and no drilling permit is allowed in these basins.  
Line 433: Line 344:
 
There is strict regulation of waste disposal or polluted  water discharge, but in some cases overruns can occur.
 
There is strict regulation of waste disposal or polluted  water discharge, but in some cases overruns can occur.
  
Domestic water is treated by the [http://www.onas.nat.tn ONAS (Office National d’Assanissement)] / National Sanitation Utility.
+
Domestic water is treated by the ONAS (Office National d’Assanissement/National Sanitation Utility) (http://www.onas.nat.tn).  
  
Irrigation schemes are managed by Agricultural Development Groups, of which there were over 2800 in 2009. A minority of these deal only with groundwater irrigation.
+
===Recharge===
 
 
===Artificial recharge===
 
  
 
A number of experiments into artificial recharge using treated waste water were carried out between 1992 and 2006 in the Cap Bon aquifer.  
 
A number of experiments into artificial recharge using treated waste water were carried out between 1992 and 2006 in the Cap Bon aquifer.  
Line 448: Line 357:
 
====Groundwater level monitoring====
 
====Groundwater level monitoring====
  
Groundwater level monitoring is done twice a year by different departments of the DGRE (there are 24 departments covering the country), using a piezometric network of more than 2,000 shallow wells and more than 1,100 deep boreholes ([http://www.semide.tn/ SEMIDE]). DGRE publish an annual report on the piezometric monitoring of deep aquifers, and a 5-yearly report on the piezometric monitoring of the phreatic aquifers. See also Horriche & Besbes (2006).  
+
Groundwater level monitoring is done twice a year by different departments of the DGRE (there are 24 departments covering the country). DGRE publish an annual report on the piezometric monitoring of deep aquifers, and a 5-yearly report on the piezometric monitoring of the phreatic aquifers. See also Horriche & Besbes (2006).
  
 
====Groundwater quality monitoring====
 
====Groundwater quality monitoring====
  
Groundwater quality is monitored twice a year by the DGRE, in September-October and March-April, at more than 1214 points: 736 wells in phreatic aquifers and 478 boreholes in deep aquifers. The main parameters monitored are total dissolved solids (TDS) and nitrate (NO<sub>3</sub>).  
+
Groundwater quality is monitored twice a year (in September-October and March-April) by the DGRE, at more than 1214 points: 736 wells in phreatic aquifers and 478 boreholes in deep aquifers. The main parameters monitored are total dissolved solids (TDS) and nitrate (NO<sub>3</sub>).
 +
The DGRE publishes the monitoring results in regular (annual or 5-yearly) reports. The SEMIDE programme also publishes monitoring results online at www.semide.tn .  
  
The DGRE publishes the monitoring results in regular (annual or 5-yearly) reports. The [https://www.semide.tn SEMIDE] programme also publishes monitoring results online.  
+
Boreholes from which groundwater is abstracted for domestic use by SONEDE are monitored monthly. SONEDE analysed 55,886 water sampels in 2013. These results are published online at https://www.sonede.com.tn/index.php?id=43 .  
  
Boreholes from which groundwater is abstracted for domestic use by SONEDE are monitored monthly. SONEDE analysed 55,886 water samples in 2013. These results are published online by [https://www.sonede.com.tn/index.php?id=43 SONEDE].
 
  
 
=== Transboundary aquifers===
 
=== Transboundary aquifers===
Line 462: Line 371:
 
Groundwater in the Djeffara coastal basin aquifer is shared between Libya and Tunisia.
 
Groundwater in the Djeffara coastal basin aquifer is shared between Libya and Tunisia.
  
Fossil groundwater in the Continental Intercalaire (CI) and Complex Terminal (CT) Northwest Saharan Aquifer System in the south of the country is shared between Tunisia, Algeria and Libya. This aquifer system has more than 1 million km³ of stored groundwater, of which some 80,000 km³ are in Tunisia. Tunisia, Algeria and Libya have established a commission to monitor the aquifer and have agreed to cooperate on its management to mimimise cross-border impacts - this is one of only two such agreements in the world. Many studies of the aquifer are carried out by the [https://www.oss-online.org Observatoire du Sahara et du Sahel (OSS)].
+
Fossil groundwater in the Continental Intercalaire (CI) and Complex Terminal (CT) Northwest Saharan Aquifer System in the south of the country is shared between Tunisia, Algeria and Libya. This aquifer system has more than 1 million km³ of stored groundwater, of which some 80,000 km³ are in Tunisia. Tunisia, Algeria and Libya have established a commission to monitor the aquifer and have agreed to cooperate on its management to mimimise cross-border impacts - this is one of only two such agreements in the world. Many studies of the aquifer are carried out by the Observatoire du Sahara et du Sahel (OSS - www.oss-online.org).
  
  
 
For further information about transboundary aquifers, please see the [[Transboundary aquifers | Transboundary aquifers resources page]]
 
For further information about transboundary aquifers, please see the [[Transboundary aquifers | Transboundary aquifers resources page]]
 +
  
 
==References==
 
==References==
  
 
The following references provide more information on the geology and hydrogeology of Tunisia.
 
The following references provide more information on the geology and hydrogeology of Tunisia.
These, 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=TN&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive]
+
These, and others, can be accessed through the [http://www.bgs.ac.uk/africagroundwateratlas/searchResults.cfm?title_search=&author_search=&category_search=&country_search=TN&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive]
  
 
===Geology: key references===
 
===Geology: key references===
  
'''A key source of geological information for Tunisia is:'''
+
'''Key sources of geological information for Tunisia are:'''
  
 
; [http://www.onm.nat.tn/fr/ National Office of Mines (ONM)].  
 
; [http://www.onm.nat.tn/fr/ National Office of Mines (ONM)].  
Line 495: Line 405:
 
The DGRE publish a number of periodical reports, including:  
 
The DGRE publish a number of periodical reports, including:  
  
* Annuaire de réalisation des forages (annually since 1994)
+
Annuaire de réalisation des forages (annually since 1994)
  
* Annuaire de l’exploitation des nappes profondes de Tunisie (annually since 1973)
+
Annuaire de l’exploitation des nappes profondes de Tunisie (annually since 1973)
  
* Situation de l’exploitation des nappes phréatiques (annually)
+
Situation de l’exploitation des nappes phréatiques (annually)
  
* Annuaire piezometrique de Tunisie (annually since 1990, with groundwater level/piezometric data from nearly 2500 monitoring points).
+
Annuaire piezometrique de Tunisie (annually since 1990, with groundwater level/piezometric data from nearly 2500 monitoring points).
  
* Annuaire de la qualité des EST
+
Annuaire de la qualité des EST
  
* Situation de l’exploitation des nappes phréatiques (every 5 years)
+
Situation de l’exploitation des nappes phréatiques (every 5 years)
  
  
Line 527: Line 437:
  
 
DGRE (Direction Generale des Ressources en Eau). 2004. [http://www.hydrosciences.fr/sierem/produits/biblio/annales/TN/2003-2004.pdf Annuaire Hydrologique de Tunisie 2003-2004].  
 
DGRE (Direction Generale des Ressources en Eau). 2004. [http://www.hydrosciences.fr/sierem/produits/biblio/annales/TN/2003-2004.pdf Annuaire Hydrologique de Tunisie 2003-2004].  
 
Ecole nationale d’ingénieurs de Sfax. [http://tcdc2.undp.org/GSSDAcademy/SIE/Docs/Vol11/SIE.v11_CH18.pdf Mapping groundwater resources: Tunisia].
 
  
 
Horriche F et Besbes M. 2006. [http://www.researchgate.net/publication/263241220_ANALYSE_DU_RSEAU_PIZOMTRIQUE_NATIONAL_TUNISIEN Analyse du réseau piézométrique national tunisien]. Journal of Water Science, 19 (4), 347-363.  
 
Horriche F et Besbes M. 2006. [http://www.researchgate.net/publication/263241220_ANALYSE_DU_RSEAU_PIZOMTRIQUE_NATIONAL_TUNISIEN Analyse du réseau piézométrique national tunisien]. Journal of Water Science, 19 (4), 347-363.  
Line 559: Line 467:
 
Zebidi H. 1991. Carte des Ressources en Eau de la Tunisie; echelle 1:500,000. Direction Generale des Ressources en Eau.
 
Zebidi H. 1991. Carte des Ressources en Eau de la Tunisie; echelle 1:500,000. Direction Generale des Ressources en Eau.
  
 +
==Return to the index pages==
  
 
Return to the index pages:
 
 
[[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Tunisia
 
[[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Tunisia
  
 
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[[Category:Hydrogeology by country|t]]
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