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Wageningen Universiteit (2003)

Leveraging water delivery : irrigation technology choices and operations and maintenance in smallholder systems in Zimbabwe

Chidenga, E.E.

Titre : Leveraging water delivery : irrigation technology choices and operations and maintenance in smallholder systems in Zimbabwe

Auteur : Chidenga, E.E.

Université de soutenance  : Wageningen Universiteit

Grade : PhD thesis 2003

Résumé
Irrigation development and management in Zimbabwe like many other sub-Saharan countries has problems related to sustainability. These problems are of a socio-technical nature related to both physical artefacts and configuration of the water delivery continuum as well as the social, economic, regulatory, financial and other institutional factors that shape the management subsystem. Six schemes in the SavecatchmentofManicalandprovince in Zimbabwe with different attributes related to water sources, mobilisation, conveyance, distribution, application and management were investigated for two cropping seasons in the period 1999 to 2000 to find out major elements that affected their sustainability. The focused on the concept ofteretechnology, thatis the ability to care for artefacts. It looked at whether this concept was present in Zimbabwe. Two old gravity surface irrigation schemes ofChakowaandDeurewere found to differ significantly due to system design and level of cooperation.Chakowascheme had no source regulation, was vulnerable to summer floods and was structured in a way that allowed head-end farmers unlimited access to water at any time leading to serious head -end tail end problems that resulted in significant differences in cropping programs and patterns. In contrastDeurehad a stabilised water source and cooperation that allowed farmers to practice across block water rotation through the distribution canal, cropping programs and patterns were similar and all farmers had access to a local niche market. This also translated to cooperation in operation and maintenance activities. AtMutema, a second-generation groundwater pumped conventional sprinkler scheme, poor water delivery due to power cuts and lack of repair resulted in salinity that lead to changes in cropping especially from vulnerable beans to mainly tomatoes and cotton. The need to save on electricity costs saw farmers at the newMusikavanhupumped surface scheme with proportional water division structures and a more reliable water delivery system deliberately enforcing reduced water supplies to winter crops. The new pumpeddraghosesprinkler system atBondeexperienced unreliable water delivery right from commissioning. This led farmers to emulate the simple gravity surface practices at theDeurewith which they share both a water source and abstraction. This is in contrast with the gravitydraghosesystem atMpudziwhere farmers on the heavier soils are engaged in full time market gardeningwiththeir main problem centring on strategies to replace worn out sprinklers or reduce the rate sprinkler wear. In conclusion it is thus observed that farmers are primarily concerned with water delivery security, and can operate systems effectively that are simple. They maintain components that are within their capacity only to avoid disruption of delivery and that the institutions need support to enhance capacity to deal with complex systems. It is therefore recommended that future planning and design of water delivery subsystems consider the engineering precepts that take into account these tere technology requirements to ensure that sustainable systems are developed such that the users can operate and maintain and using local resources and available managerial support structures from government and the private sector and other production related structures like markets to leverage the water delivery.

Mots clés : irrigation / irrigated farming / irrigation systems / small farms / management / water distribution / technology / zimbabwe

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Page publiée le 24 mars 2007, mise à jour le 3 juin 2022