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Tottori University (2013)

Integrated operation and management of irrigation systems for sustainable agriculture under arid environment

Ahmed Mohsen Aly Mohamed

Titre : Integrated operation and management of irrigation systems for sustainable agriculture under arid environment

Auteur : Ahmed Mohsen Aly Mohamed

Université de soutenance : Tottori University

Grade : Doctoral Thesis 2013

Sommaire partiel
Climate changes will significantly impact agriculture by increasing water demand and reducing water availability in areas where irrigation is most needed, especially in arid regions. The agricultural water management in the Nile Delta will be impacted by climate change increasing prone to flood and storm damage or experience salinity intrusion through surface and groundwater. A factor affecting the Delta water budget is also the uncertainty of precipitation and flows in the Nile river catchment that has been predicted to slightly decrease by 5% in the future decades over sub-catchments of the Blue Nile. The Blue Nile contributes about 60% of its total mean annual flow to Aswan High Dam in Egypt (84 × 109 m 3). Therefore, efficient operation and management of an irrigation system plays an important role in the sustainability of irrigated agriculture because the climate changes will have impacts on decisions of water management and use. Due to its limited water resources, Egypt faces great challenges to enforce policies to improve the performance of the existing delivery system by implement more effective irrigation technologies. Improvements consist of a demand delivery system using mechanical gate structures and controllers to automatically divert water from one portion of a network to another in the desired amount and sequence. This study was carried out to evaluate and understand the farmers’ irrigation practices in their farms before and after modification of the existing irrigation system. In addition, I also evaluated the irrigation network system under government management before and after these improvements in the existing irrigation networks. El-Wasat command area is selected as study area, where paddy rice, one of the most common crop in the Nile Delta, Egypt. Rice contributes 40% of total crop production. This area is located on the northern edge of the Nile Delta, and it is fed from the tail reaches of the main canal. Due to its location, El-Wasat command area receives less amount of water and suffers from shortage of water supply. Moreover, farmers tend to plant more fields with paddy rice than the limit government set (at 50%) and this causes increase of water demand. Therefore, an unbalance of water supply and demand is exacerbated. A set of performance indicators proposed by Molden and Gates (1990) have been employed for the evaluation of the study. The indicators to evaluate irrigation delivery performance require different data items such as water level, routine discharges, and cropping pattern for branch canals, pump operations for tertiary canals and irrigation events of selected farmers. Data were analyzed, and the values of different indicators are calculated. The results indicate that the water-use application at the improved system is improved. This is due the successful management and operation of the water-supply system by the water users association. Water users’ association has a positive effect on managing of the improved tertiary canal. For unimproved system, the results indicate that irrigation delivery by traditional rotation systems is unsuitable at the irrigation districts that are located at the end of large irrigation networks in the Nile Delta, while the demand delivery concept is successful in improving water delivery performance over that of the traditional rotation delivery concept used previously. The new system provided fair shares of water among irrigation districts and allows the irrigation districts to deliver water from main canal whenever they need water. In addition, the automation improves efficiency, responsiveness, and flexibility of canal system. There still remain main problems of water delivery in the irrigation networks and that is a water shortage in the main canal due to its location at the tail of the feeder canal system in the Nile Delta, and other reasons include rice-farmers’ nonobservance of summer crop production plan designed by government. It causes the greater demand of some fields than supply.

Annonce de la thèse

Page publiée le 26 octobre 2016, mise à jour le 19 avril 2020