Embed Size (px)
Citation preview
6th World Water ForumMarseille, 12-17.03.2012
Low cost Solutions for the Irrigation Efficiency improvement in the Maghreb oases-
Study case of Southern Tunisia
Institute of Arid Regions (IRA) - Tunisia
Nizar Omrani & Prof. Dr. Dieter BurgerIfGG, Karlsruhe Institute of Technology (KIT)
In the arid lands of the Maghreb countries (Tunisia, Algeria and Morocco), the oases still represent very particular irrigated perimeters with high crop production potential.
For the case of southern Tunisia, as well as for the neighbors countries, the introduction of the sprinkler and the drip irrigation for the main cultivations systems which is the date palm, remains definitely a technical challenge and requires relevant installation costs.
Nevertheless, under the water shortage context, the irrigation management became a crucial issue that preconditions the development of the oases. The efficiency of the surface irrigation and the water productivity inside farmers plots remained low and are focusing a cross disciplinary commitment from research and development actors.
2
Context:
Kit Solution Description:
The solution had been initiated within the framework of the cooperation between the Karlsruhe Institute of Technology (KIT), the institute of Arid Regions (IRA) and the
German technical Cooperation (GIZ).
The test in pilot farms of the irrigation systems (near surface sprinkler design) of PVC pipes using simply the water borne delivered discharge (less than 0.5 m) had been
implemented in Atilet, kebili Oasis in the southern Tunisia.
The technical installation of those irrigation techniques could be operated by the farmers community often organized in common interest groups (GIC). It should be than supervised by the local agriculture development organization for technical maintenance.
4
Kit Solution Description:
Farmers training by the Governmental vulgarization agencies and the German technical cooperation for the water saving practice inside farms is highly recommended prior to the
irrigation kit implementation.
The design of the irrigation systems could be easily by the local development agency supervised, the plastic materials are also simply in local markets available.
Low Cost Irrigation Kit DesignLow Cost Irrigation Kit Design
Alternative 1:Alternative 1: 2nd order Distributing pipe + basin irrigation; less effective, but relative cheap
Alternative 2:Alternative 2: 3rd order ‚punched‘ distribution pipe with holes e.g. every one meter
Alternative 3:Alternative 3: Two line distribution pipe for better water distribution
Alternative 4:Alternative 4: Two line distribution pipe with near-surface sprinklers. Precondition: 40 cm distance in height (0.4 bar needed)
alternative 1
= Outlet 63 mm
= Head Indicator
= Pipe PVC, ø= 63 mm
alternative 2
alternative 3
= Outlet 50 mm
= Head Indicator
= Pipe PVC, ø= 63 mm
= Pipe PVC, ø= 50 mm
Connexion to the public Connexion to the public irrigation networkirrigation network Oasis Rejim Maatoug, TunisiaOasis Rejim Maatoug, Tunisia
Photo: Ghazouani, 2007
Conversion from submersion method (A) to Low cost irrigation systems (B, C) implemented in Atilet, Kebili-Southern Tunisia Photo: Omrani, 2011
A
B
C
Conditions for success:
National policies in the irrigated sector emphasizes on the framer’s plots irrigation performance improvement. Several subsidies are being allocated to encourage the implementation of the water saving techniques inside farmer’s plot (20 %, 40 % and 60 % of the installation cost respectively for the big, medium and small farms).
The presence of Farmer’s group’s structure already good organized which would facilitate the implementation of the solution within the oases.
There is a real demand from the farmers group of concrete tools to enhance the parcels productivity and to overcome the water shortage in the summer period when the irrigation network become unable to satisfy the demand (high infiltration rate during the surface irrigation in the farmers plots).
11
The added value:
The introduction of low cost irrigation system for more water saving approach. The irrigation efficiency at the parcel more than 80 % while it had been 60 % in best case with the former improved surface method.
With the conventional drip irrigation material, there are recurrent problems of drippers warping by salt especially in summer period, our irrigation kit avoid such constraint, the near-surface sprinklers provide a uniform water application in the irrigation basin.
With a strict application of the recommended low cost irrigation technique , the water productivity attempts 0,51 kg/m3 while it could be, according to the state of art (Simmoneau, 1961), nearby 0,25 kg/m3.
Depending on the irrigation design types that could be recommended from our panel, the installation cost for an irrigated range from 1220 €uro/ha to 2800 €uro/ha.
There is no need to pumping, relevant energy costs are spared. The water supply could be operated with the discharge prevailing in the irrigation network. Nevertheless, considering the technical constraints that could afford such technique, the implementation of storage reservoir provide (0.4 to 0.5 m discharge) provides more flexibility for farmers to manage his parcel irrigation.
13
Replication potential:
This irrigation kit could installed within all the oases as alternative to the traditional surface method.
With use of brackish water, such irrigation system avoid the warping problem and the salt crust formation as it is the case with the conventional drippers.
Tunisia, Algeria and Lybia are using a common underground water resources SASS, such brackish water requires the recourse to alternative irrigation systems to resolve
the mentioned problems.
The prevailing water management condition in the Maghreb countries oases as well as the well structured irrigation scheme of these arid lands, reinforce the up scaling
potential of such solution.
