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UNESCO-IHE Institute for Water Education, Delft (2015)

Towards improved operation and maintenance practices for enhanced irrigation water delivery services : case study : Gezira Irrigation Scheme in Sudan

Ntazinda, P.

Titre : Towards improved operation and maintenance practices for enhanced irrigation water delivery services : case study : Gezira Irrigation Scheme in Sudan

Auteur : Ntazinda, P.

Université de soutenance : UNESCO-IHE Institute for Water Education, Delft

Grade : Master of Science (MS) 2015

Résumé
With the growing population and increasing demand for food, the irrigated agriculture must be improved to provide sustainable food production. With finite freshwater and land resources, and the increasing competition over these precious resources, irrigated agricultural use of land and water resources must be improved to produce more food per unit water. Therefore, the information on the performance indicators of water delivery is needed to devise appropriate water management strategies. Practically, the input data required for the assessment of irrigation performance are difficult to obtain due to the necessity of costly intensive field campaigns.In this study, the evapotranspiration maps obtained from waterwatch were used to compute theperformance indicators of equity, adequacy and reliability for the Gezira Scheme (GS) in Sudan. The results of water delivery performance indicators for the whole scheme and the three selected major (sub-main) canal subdivisions at the head, middle and tail of GS highlighted the poor performance with respect to the standard indicators of Molden & Gates (1990). The coefficients of variability in water consumption indicating the equity were above 0.25 and values for the average seasonal relative evaporation indicating the adequacy were below 0.8 while values for the temporal variation of the relative evaporation indicating reliability of water delivery were greater than 0.2.The issues related to operation and maintenance and how they impact the irrigation performance have beeninvestigated in the 3 selected major (sub-main) canal subdivisions and a sample of 2 minor (secondary)canals was selected within each subdivision for field surveys. The field data collection was enriched by the additional information collected through semi-structured interviews with farmers and some people directly involved in the irrigation work. The problems affecting the poor performance in water delivery are a combination of operational and maintenance issues. Lack of irrigation planning and uncontrolled operation leading to over-abstraction of upstream users underlie the operational issues. The lack of irrigation planning mostly affects water adequacy and reliability while the uncontrolled operation highly contributes to thepoor equity in water distribution. On the other hand, the identified maintenance issues were mainly related to the damaged and dysfunctional irrigation structures and canal over-excavation which led to the loss of water through dead storage and thus affecting negatively the adequacy of water delivery. To redress the identified issues ; the study recommended measures to be adopted in order to improve the irrigation water delivery services.The study also identified the effects of past major technical interventions on operation and maintenance andaccordingly tried to show their relation with the trend in irrigated areas and crop yields over the past years. It was found that some technical interventions contributed directly to the rising trends but they could not be sustained over a long period.

Sujets  : irrigation schemes water delivery performance water management operation and maintenance case studies Sudan

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Page publiée le 12 février 2020