Recharge well [Tunisia]
- Creation:
- Update:
- Compiler: Mongi Ben Zaied
- Editor: –
- Reviewer: Fabian Ottiger
Puits de recharge (French)
technologies_1412 - Tunisia
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Expand all Collapse all1. General information
1.2 Contact details of resource persons and institutions involved in the assessment and documentation of the Technology
Key resource person(s)
SLM specialist:
Chniter Mongi
Commissariats Régionaux au Développement Agricole CRDA
4100 Medenine, Tunisia
Tunisia
SLM specialist:
Yahyaoui Houcine
Commissariats Régionaux au Développement Agricole CRDA
4100 Medenine, Tunisia
Tunisia
SLM specialist:
Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)
Commissariats Régionaux au Développement Agricole (CRDA) - TunisiaName of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)
Institut des Régions Arides de Médenine (Institut des Régions Arides de Médenine) - Tunisia1.3 Conditions regarding the use of data documented through WOCAT
When were the data compiled (in the field)?
10/06/2011
The compiler and key resource person(s) accept the conditions regarding the use of data documented through WOCAT:
Yes
2. Description of the SLM Technology
2.1 Short description of the Technology
Definition of the Technology:
A recharge well comprises a drilled hole, up to 30-40 m deep that reaches the water table, and a surrounding filter used to allow the direct injection of floodwater into the aquifer.
2.2 Detailed description of the Technology
Description:
The main worldwide used methods to enhance groundwater replenishment are through recharge basins or recharge wells. Though groundwater recharge aiming at storage of water in the periods of abundance for recovery in times of drought has a long history dating back millennia, the recharge wells began to be used only in the twentieth century, especially during the Second World War following concerns on attacks of the water supply facilities. Its use was extended later to sea intrusion control, treated waste water, water harvesting in the dry areas, and strategic water storage.
Purpose of the Technology: Recharge wells are used in combination with gabion check dams to enhance the infiltration of floodwater into the aquifer. In areas where the permeability of the underlying bedrock in front of a gabion is judged too low, recharge wells could be installed in wadi (ephemeral river) beds. Water is retained by the gabion check dam and it flows through the recharge well allowing accelerated percolation into the aquifer.
Establishment / maintenance activities and inputs: A recharge well consists of a long inner tube surrounded by an outer tube, the circumference of which ranges between 1 and 2 m. The area between the tubes is filled with river bed gravel which acts as a sediment filter. Water enters the well through rectangular-shaped openings (almost 20 cm long and a few mm in width) located in the outer tube, and it flows in the inner hole having passed through the gravel and the rectangular shaped openings of the dill hole. The above-ground height is around 2 to 3 m whereas the depth is linked to the depth of the water table (normally up to 40 m). The drill hole connects directly with the aquifer, where it is connected either directly with the water table or indirectly via cracks. Pond volume is dependent on the size of the gabion check dam but generally ranges between 500 and 3000 m3. The filtered water can directly flow into the aquifer at a rate exceeding what would occur naturally through the soil and the underlying strata.
The design should be conducted primarily by a hydrogeologist and a soil and water conservation specialist in order to determine the potential sites and the required drilling equipment. Drilling needs to be carried out by a specialized company.
Depending on the geological setting, the overall cost is around 5000 to 10000 US$. The recharge wells are used to recharge the deep groundwater aquifers, which are mainly exploited by government agencies. However, private irrigated farms are benefiting indirectly by increased groundwater availability.
Natural / human environment: This technique has been first tried for the replenishment of the Zeuss-Koutine aquifer (south east Tunisia).
2.3 Photos of the Technology
2.5 Country/ region/ locations where the Technology has been applied and which are covered by this assessment
Country:
Tunisia
Region/ State/ Province:
Medenine
Further specification of location:
Medenine nord
Map
×2.6 Date of implementation
If precise year is not known, indicate approximate date:
- 10-50 years ago
2.7 Introduction of the Technology
Specify how the Technology was introduced:
- through projects/ external interventions
3. Classification of the SLM Technology
3.2 Current land use type(s) where the Technology is applied
![Cropland](/static/assets/img/pictos/land_1.png)
Cropland
- Tree and shrub cropping
![Grazing land](/static/assets/img/pictos/land_5.png)
Grazing land
Comments:
Major land use problems (compiler’s opinion): Runoff water loss, riverbank erosion, flooding risk, aridity
Major land use problems (land users’ perception): water loss
Constraints of wadi beds
3.3 Further information about land use
Number of growing seasons per year:
- 1
Specify:
Longest growing period in days: 180Longest growing period from month to month: Oct - Apr
3.4 SLM group to which the Technology belongs
- water harvesting
- ground water management
3.5 Spread of the Technology
Specify the spread of the Technology:
- evenly spread over an area
If the Technology is evenly spread over an area, indicate approximate area covered:
- 10-100 km2
3.6 SLM measures comprising the Technology
![structural measures](/static/assets/img/pictos/swc_1_struc.png)
structural measures
- S11: Others
Comments:
Main measures: structural measures
3.7 Main types of land degradation addressed by the Technology
![soil erosion by water](/static/assets/img/pictos/degra_watererosion.png)
soil erosion by water
- Wr: riverbank erosion
- Wo: offsite degradation effects
![water degradation](/static/assets/img/pictos/degra_waterdegrade.png)
water degradation
- Ha: aridification
- Hq: decline of groundwater quality
Comments:
Main type of degradation addressed: Ha: aridification
Secondary types of degradation addressed: Wr: riverbank erosion, Wo: offsite degradation effects, Hq: decline of groundwater quality
Main causes of degradation: over abstraction / excessive withdrawal of water (for irrigation, industry, etc.)
Secondary causes of degradation: disturbance of water cycle (infiltration / runoff), Heavy / extreme rainfall (intensity/amounts)
3.8 Prevention, reduction, or restoration of land degradation
Specify the goal of the Technology with regard to land degradation:
- prevent land degradation
- reduce land degradation
Comments:
Main goals: prevention of land degradation
Secondary goals: mitigation / reduction of land degradation
4. Technical specifications, implementation activities, inputs, and costs
4.1 Technical drawing of the Technology
4.2 Technical specifications/ explanations of technical drawing
Schematic representation of the main components of a recharge well. The flood water retained behind the gabion check dam flows through the outer tube and the gravel filter into the water table. Clogging of the filter is one of the major problems to be considered and solved.
south east Tunisia
Date: January 2009
Technical knowledge required for field staff / advisors: moderate
Main technical functions: increase of groundwater level / recharge of groundwater
Secondary technical functions: control of concentrated runoff: retain / trap, water harvesting / increase water supply
Structural measure: Casting tube
Spacing between structures (m): 100-500
Depth of ditches/pits/dams (m): 30-40m
Width of ditches/pits/dams (m): 0.5-1m
Structural measure: Filter
Construction material (other): Plastic/iron: the casting tube, Gravel: for the filter
4.3 General information regarding the calculation of inputs and costs
other/ national currency (specify):
TND
Indicate exchange rate from USD to local currency (if relevant): 1 USD =:
1.3
Indicate average wage cost of hired labour per day:
10.00
4.4 Establishment activities
Activity | Type of measure | Timing | |
---|---|---|---|
1. | Drilling | Structural | |
2. | Installation | Structural |
4.5 Costs and inputs needed for establishment
Specify input | Unit | Quantity | Costs per Unit | Total costs per input | % of costs borne by land users | |
---|---|---|---|---|---|---|
Labour | Labour | ha | 1.0 | 7000.0 | 7000.0 | |
Construction material | ha | 1.0 | 1000.0 | 1000.0 | ||
Total costs for establishment of the Technology | 8000.0 |
Comments:
Duration of establishment phase: 3 month(s)
4.6 Maintenance/ recurrent activities
Activity | Type of measure | Timing/ frequency | |
---|---|---|---|
1. | Desilting of the filter | Structural | Ounce in 1-3years (floods) |
2. | Repairs | Structural |
4.7 Costs and inputs needed for maintenance/ recurrent activities (per year)
Specify input | Unit | Quantity | Costs per Unit | Total costs per input | % of costs borne by land users | |
---|---|---|---|---|---|---|
Labour | Labour | ha | 1.0 | 500.0 | 500.0 | |
Construction material | ha | 1.0 | 100.0 | 100.0 | ||
Total costs for maintenance of the Technology | 600.0 |
4.8 Most important factors affecting the costs
Describe the most determinate factors affecting the costs:
Labour is the most determining factor affecting the costs.
5. Natural and human environment
5.1 Climate
Annual rainfall
- < 250 mm
- 251-500 mm
- 501-750 mm
- 751-1,000 mm
- 1,001-1,500 mm
- 1,501-2,000 mm
- 2,001-3,000 mm
- 3,001-4,000 mm
- > 4,000 mm
Agro-climatic zone
- arid
Thermal climate class: subtropics
5.2 Topography
Slopes on average:
- flat (0-2%)
- gentle (3-5%)
- moderate (6-10%)
- rolling (11-15%)
- hilly (16-30%)
- steep (31-60%)
- very steep (>60%)
Landforms:
- plateau/plains
- ridges
- mountain slopes
- hill slopes
- footslopes
- valley floors
Altitudinal zone:
- 0-100 m a.s.l.
- 101-500 m a.s.l.
- 501-1,000 m a.s.l.
- 1,001-1,500 m a.s.l.
- 1,501-2,000 m a.s.l.
- 2,001-2,500 m a.s.l.
- 2,501-3,000 m a.s.l.
- 3,001-4,000 m a.s.l.
- > 4,000 m a.s.l.
5.3 Soils
Soil depth on average:
- very shallow (0-20 cm)
- shallow (21-50 cm)
- moderately deep (51-80 cm)
- deep (81-120 cm)
- very deep (> 120 cm)
Soil texture (topsoil):
- medium (loamy, silty)
Topsoil organic matter:
- low (<1%)
If available, attach full soil description or specify the available information, e.g. soil type, soil PH/ acidity, Cation Exchange Capacity, nitrogen, salinity etc.
Soil fertility is very low
Soil drainage / infiltration is medium
Soil water storage is medium
5.4 Water availability and quality
Ground water table:
5-50 m
Availability of surface water:
poor/ none
Water quality (untreated):
poor drinking water (treatment required)
Comments and further specifications on water quality and quantity:
Seasonal fluctuations: Availability of surface water is poor/none but with periods of excess (e.g. flood)
5.5 Biodiversity
Species diversity:
- medium
5.6 Characteristics of land users applying the Technology
Market orientation of production system:
- mixed (subsistence/ commercial
Off-farm income:
- > 50% of all income
Relative level of wealth:
- average
Individuals or groups:
- employee (company, government)
Indicate other relevant characteristics of the land users:
Population density: 10-50 persons/km2
Annual population growth: 0.5% - 1%
70% of the land users are average wealthy and own 75% of the land.
5.7 Average area of land owned or leased by land users applying the Technology
- < 0.5 ha
- 0.5-1 ha
- 1-2 ha
- 2-5 ha
- 5-15 ha
- 15-50 ha
- 50-100 ha
- 100-500 ha
- 500-1,000 ha
- 1,000-10,000 ha
- > 10,000 ha
5.8 Land ownership, land use rights, and water use rights
Land ownership:
- state
Land use rights:
- communal (organized)
Water use rights:
- communal (organized)
Comments:
The recharge wells are used to recharge the deep groundwater aquifers which are mainly exploited by the government agencies. However, private irrigated farms could benefit indirectly, by increased groundwater availability.
5.9 Access to services and infrastructure
health:
- poor
- moderate
- good
education:
- poor
- moderate
- good
technical assistance:
- poor
- moderate
- good
employment (e.g. off-farm):
- poor
- moderate
- good
markets:
- poor
- moderate
- good
energy:
- poor
- moderate
- good
roads and transport:
- poor
- moderate
- good
drinking water and sanitation:
- poor
- moderate
- good
financial services:
- poor
- moderate
- good
6. Impacts and concluding statements
6.1 On-site impacts the Technology has shown
Socio-economic impacts
Water availability and quality
drinking water availability
water availability for livestock
irrigation water availability
Socio-cultural impacts
SLM/ land degradation knowledge
conflict mitigation
Improved livelihoods and human well-being
Comments/ specify:
Increased availability of water for drinking, agriculture and livestock
Ecological impacts
Water cycle/ runoff
harvesting/ collection of water
groundwater table/ aquifer
Soil
salinity
Other ecological impacts
risks of contamination of aquifers
6.2 Off-site impacts the Technology has shown
water availability
downstream flooding
Comments/ specify:
In combination with gabion check dams
damage on public/ private infrastructure
Comments/ specify:
In combination with gabion check dams
Surface water to reach downstream areas
6.3 Exposure and sensitivity of the Technology to gradual climate change and climate-related extremes/ disasters (as perceived by land users)
Gradual climate change
Gradual climate change
Season | Type of climatic change/ extreme | How does the Technology cope with it? | |
---|---|---|---|
annual temperature | increase | well |
Climate-related extremes (disasters)
Meteorological disasters
How does the Technology cope with it? | |
---|---|
local rainstorm | well |
local windstorm | well |
Climatological disasters
How does the Technology cope with it? | |
---|---|
drought | well |
Other climate-related consequences
Other climate-related consequences
How does the Technology cope with it? | |
---|---|
reduced growing period | well |
extreme floods | not well |
6.4 Cost-benefit analysis
How do the benefits compare with the establishment costs (from land users’ perspective)?
Short-term returns:
very positive
Long-term returns:
positive
How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?
Short-term returns:
very positive
Long-term returns:
positive
Comments:
Long-term benefits are slightly reduced due to silting problems.
6.5 Adoption of the Technology
Of all those who have adopted the Technology, how many have did so spontaneously, i.e. without receiving any material incentives/ payments?
- 0-10%
Comments:
Comments on acceptance with external material support: It is solely constrcuted by the government agencies.
6.7 Strengths/ advantages/ opportunities of the Technology
Strengths/ advantages/ opportunities in the land user’s view |
---|
Replenishment of the aquifer How can they be sustained / enhanced? Good selection of the site and drilling methods |
Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view |
---|
Enhance groundwater level and quality (reduce salinity) |
6.8 Weaknesses/ disadvantages/ risks of the Technology and ways of overcoming them
Weaknesses/ disadvantages/ risks in the land user’s view | How can they be overcome? |
---|---|
Retain water for dowstreams users | Proper watershed management plan |
Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view | How can they be overcome? |
---|---|
Silting up of the filter | Maintenance of the filters. |
Malfunction due to aquifer geometry and characteristics | Good selection of the sites |
7. References and links
7.2 References to available publications
Title, author, year, ISBN:
Yahyaoui, H., Ouessar, M. 2000. Abstraction and recharge impacts on the ground water in the arid regions of Tunisia: Case of Zeuss-Koutine water table. UNU Desertification Series, 2: 72-78.
Available from where? Costs?
IRA, CRDA-Medenine, UNU
Title, author, year, ISBN:
Yahyaoui, H., Chaieb, H., Ouessar, M. 2002. Impact des travaux de conservation des eaux et des sols sur la recharge de la nappe de Zeuss-Koutine (Médenine: Sud-est tunisien). TRMP paper n° 40, Wageningen University, The Netherlands, pp: 71-86.
Available from where? Costs?
IRA, Wegeningen University (NL),
Title, author, year, ISBN:
Temmerman, S. 2004. Evaluation of the efficiency of recharge wells on the water supply to the water table in South Tunisia. Graduation dissertation, Ghent University, Belgium.
Available from where? Costs?
IRA, Gent University (BE)
Title, author, year, ISBN:
Genin, D., Guillaume, H., Ouessar, M., Ouled Belgacem, A., Romagny, B., Sghaier, M., Taamallah, H. (eds) 2006. Entre la désertification et le développement : la Jeffara tunisienne. CERES, Tunis, 351 pp.
Available from where? Costs?
IRA, IRD
Title, author, year, ISBN:
Ouessar M. 2007. Hydrological impacts of rainwater harvesting in wadi Oum Zessar watershed (Southern Tunisia). Ph.D. thesis, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium, 154 pp.
Available from where? Costs?
IRA, Gent University (BE)
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