Optimization in Water Management for Sustainable Irrigated Rice Production in Central Côte d’Ivoire Under Rainfall Variability

Irrigation is a major challenge of food self-sufficiency because of the demographic conditions of Ivorian cities, combined with climate variability. The aim of this study is to analyze and optimize practices management of rice irrigation in Nanan, at the central Cote d’Ivoire under rainfall variability. Methodological approach adopted was multidisciplinary and participatory. Climatic, agro-pedological, hydrometric and sociological data was used in this study. Results showed that rainfall variability is a reality and is characterized by alternating dry and wet periods. Agricultural practices analysis showed low value of crop intensity with 108% and 88% in 2016 and 2017 respectively. Irrigation efficiency is estimated at 37%. The results also showed a mismatch between water withdrawals and water needs, which vary between 4% and 80%. A poor annual distribution of rice transplanting with almost no transplanting during the first cycle was observed. Facing to these malfunctions, a reorganization of farming practice was recommended. This starts with harmonization of transplanting date and implementation of optimized water management methods. The periods from March to April, and September to October was identified as the optimal transplanting periods for the first and second cycles respectively. In addition, Height-Flow -Turn of Valve curve was carried out to help valve manager estimate water needed quantities. Finally, telephone fleet was proposed as communication way, to improve water distribution method by rotation between rice farmers.