Desire for Greener Land

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Recharge well Tunisia - Puits filtrant (French) 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. 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. 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. 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 drill 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 m 3 . 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. SLM Technology: Recharge well, Tunisia DESIRE – WOCAT 2012 Above left: A recharge well reduces the length of time of standing water, and thus evaporation, by injecting flood water rapidly into the aquifer, where it is stored and recovered later to be used for different purposes. This is an example of a recharge well behind a gabion check dam after rain. (Photo: Ouessar M.) Above right: A recharge well needs to be always combined with a gabion check dam which prevents floodwater movement downstream and creates a temporary pond (Photo: Temmerman S.) Location: Medenine Region: Medenine nord Technology area: 10 - 100 km 2 Conservation measure: structural Stage of intervention: prevention of land degradation Origin: externally - 10-50 years ago Land use: cropland, grazing land Climate: arid, subtropics WOCAT database reference: QT TUN14 on cdewocat.unibe.ch/wocatQT DESIRE site information: www.desirehis.eu/en/zeuss-koutine-tunisia Related approach: Dryland watershed management approach (QA TUN09) Compiled by: Mohamed Ouessar, Houcine Yahyaoui, Institut des Régions Arides (IRA), Tunisia Date: 31 st Jan 2009, updated 10 th Jun 2011 125
Classification Land use problems: Runoff water loss, riverbank erosion, flooding risk, aridity Land use Climate Degradation Conservation measure tree and shrub extensive grazing cropping land Stage of intervention Prevention Mitigation / Reduction Rehabilitation Soil depth (cm) 0-20 20-50 50-80 80-120 >120 Growing season(s): 180 days (Oct - Apr) Soil texture: medium (loam) Soil fertility: very low Topsoil organic matter: low (
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Desire for Greener Land Options for
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DESIRE - WOCAT Desire for Greener L
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Co-published by University of Bern,
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Cross-slope barriers Progressive be
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The present DESIRE publication desc
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Contributing authors and DESIRE con
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Desire for Greener Land - Options f
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XIV DESIRE - WOCAT Desire for Green
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Figure 1: Desertification vulnerabi
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In DESIRE, WOCAT methods and tools
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Part 1
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8 DESIRE - WOCAT Desire for Greener
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Figure 1: Methodological framework
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to Russia and China (see Table 1).
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DRI = 5.4 Very high desertification
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Table 2 provides a more detailed de
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decision. This leads to solutions b
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Aims and objectives This penultimat
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Figure 7: The DESIRE Project has fo
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References: n EEA-European Environm
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Area (x1000 Ha) Major land use type
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Major land degradation types per st
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Rate of degradation per study site
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Production services were affected o
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% of area under conservation measur
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Figure 16: Effectiveness of conserv
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Conservation impact on ecosystem se
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Analysis of SLM technologies Introd
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Table 2: WOCAT categories of SLM me
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Origin of technology SLM technologi
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Table 3: Sensitivity of and toleran
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No. of case studies Land Ownership
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No. of case studies Increased farm
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No. of case studies Improved harves
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No. of case studies Increased plant
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No. of case studies No. of case stu
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Analysis of SLM approaches Introduc
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system is focused on control rather
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References: n Alkemade, J. R. M., v
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actually implemented in the field.
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Concerning SLM, the most widely app
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Part 2 DESIRE - WOCAT Desire for Gr
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Desire for Greener Land Mexico Land
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2.1 SLM case studies Case studies -
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Assessment Impacts of the Technolog
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Classification Land use problems: O
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Class sification Land use problemss
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Classification Land use problems: T
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Classification Land use problems: O
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Problem, objectives and constraints
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Impacts of the Approach Improved su
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Input: - Equipment (machinery, tool
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Problems, objectives, and constrain
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Desire for Greener Land Opopejo Qui
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2.2 Mapping case studies This secti
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Land recommendation Land conservati
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Portugal - Maçao The Maçao area h
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Italy - Rendina The Rendina area ex
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Greece - Nestos This area has chemi
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Turkey - Eskişehir The Eskeheşir
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Tunisia - Koutine The Koutine area
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Russia - Novy Land use in the Novy
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Botswana - Boteti The main land use
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Chile - Cauquenes The Cauquenes are
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252 DESIRE - WOCAT Desire for Green
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Status of land degradation, sustain
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Examples of potential SLM technolog
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IV Up-scaling SLM strategies Actual
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Case study of the DESIRE methodolog
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II Identifying, evaluating and sele
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The results showed that the best op
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IV Up-scaling SLM strategies Some r
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Explanation pages of case studies:
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Cropland (or grazing land, mixed la
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Explanation pages of case studies:
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Here appears an organogram - if ava
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Pictograms SLM technology Land use
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Logos of partners 282 DESIRE - WOCA
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Desire for Greener Land

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