Delivery basin and energy dissipation structure (Minamba Traore, IICEM)
The irrigation area’s main earthen canals have their inverts lined in concrete and their sides lined with solid cement blocks. Concrete support posts are set at intervals and capped in concrete. Each lined main canal should be no longer than two kilometres. The main canal’s turnouts into the secondary canals are built in cement and are equipped with gates that can be opened and closed as required.
Each turnout’s outflow area is protected by a rockfill structure that is built right up to the top of the canal wall to prevent the canal banks at the head of the secondary canals from becoming degraded.
Lining is mainly used to improve the efficiency of existing irrigation systems. Once the canal has been lined, yields increase by between 35% and 80%. This is because crops receive the water they need to ripen as and when it is required. Often, lining also makes it possible to extend the irrigated area. Pumping hours per hectare are considerably reduced (by 25% in the rainy season) because the canals ensure the correct distribution of irrigation water. Consequently, irrigation costs per tonne of produce drop due to the reduction in pumping hours and the costs of periodical maintenance and increases in yields.
Together with the growers, a memorandum of understanding was drawn up with IICEM and then signed by the mayor. The memorandum describes all the activities that form part of the collaboration between IICEM and the various beneficiaries. The works were carried out either in-company or constituted part of the highly labour-intensive work (HLIW).
a) Work delivered in-company (turnkey basis): Works are carried out in several stages: 1) Identifying the sites requiring lining. This involves locating the sites to develop and making contact with the NGOs that represent the project in the region, as well as regional directorates of rural engineering and economic operators working with the farming organisations in question. 2) The delimited sites chosen for development must undergo technical studies, which are entrusted to engineering consultancies recruited through an open tender process in accordance with the terms of reference for the studies to be conducted. 3) The technical feasibility studies comprise topographical, geotechnical, soil and environmental studies, as well as the creation of a development plan and quantification of materials required for the construction work. 4) Drawing up the invitation to tender (ITT) documents and communicating the tender process to businesses. In lieu of a ToR, an ITT is created by the project according to the requirements of the site. It is then published so that interested consultancies can put forward their bids. 5) Works are carried out under the control and supervision of the oversight office to ensure they adhere to professional standards.
b) Highly labour-intensive work: 1) The same as above. 2) Topographical surveys are carried out by IICEM specialists to calculate the calibration of the canals to ensure they are able to submerge plots over a large area. 3) After calibrating the schemes (energy dissipation basin and division box, main canal and secondary canal turnout, channel), a work plan is drawn up. This uses the measurements calculated to quantify construction material and equipment requirements. 4) Teams of (preferably local) builders are recruited to line the canals. The teams comprise master builders, reinforcing ironworkers, bricklayers and surveyors. 5) The materials and equipment required for each site are provided by an appropriate supplier recruited through a tendering process. 6) Provision of labour and farmer participation. Only the building contractors are paid for working on the project. Labour is supplied by the local community who are provided with lunch to maintain motivation and to prevent lost time caused by workers going off-site. 7) In villages where schemes are proposed, teams of shift workers from the local community are set up and trained in proper conduct for working on a canal lining project and in the keeping of a construction project log book.
Once the canal lining works are complete, IICEM provides a pump unit and subsidises the required fuel and consumables for one growing season. Training in how to run and maintain pump units is provided for the local beneficiaries tasked with their upkeep. Furthermore, training in the management and maintenance of irrigation schemes is delivered to the farming organisations’ steering committee.
The lifespan of a canal lining ranges from 10 to 20 years if small repairs are regularly undertaken. Ensuring linings are impermeable is of the utmost importance because water penetrating through micro-cracks as it flows through the network can lead to rapid and major water loss. It is therefore essential that producers can maintain installations and repair cracks.
The Sahel is a region where the population has always faced a high degree of climate variability, manifested both in terms of time (unexpected dry spells can occur during the rainy season) and in terms of space (rainfall can vary greatly from one area to another). The population is mainly composed of small farmers and livestock keepers.
Over the last two decades, the effects of climate change have exacerbated the already difficult conditions. Accord¬ing to projections made by climatologists, the Sahel will experience a rise in temperatures combined with highly variable rainfall and an increase in extreme weather events.
The Soil and Water conservation and rehabilitation techniques have helped people in the Sahel to manage their ecosystems more effectively and improve their productive land. As a result, communities are better prepared to cope with environmental changes (changes in the climate, land degradation, etc.) and the im¬pact of shocks, particularly droughts
ສະຖານທີ່: Mopti, Timbuktu, Gao, Sikasso, Mali, ມາລິ
ຈໍານວນ ພື້ນທີ່ ທີ່ໃຊ້ ເຕັກໂນໂລຢີ ທີ່ໄດ້ວິເຄາະ:
ການແຜ່ກະຈາຍຂອງເຕັກໂນໂລຢີ: ແຜ່ຂະຫຍາຍຢ່າງໄວວາໃນພື້ນທີ່ (12.0 km²)
ຢູ່ໃນເຂດປ່າສະຫງວນທີ່ບໍ?:
ວັນທີຂອງການປະຕິບັດ: ຕໍ່າກວ່າ 10 ປີ ຜ່ານມາ (ມາເຖິງປະຈຸບັນ)
ປະເພດຂອງການນໍາສະເໜີ
