Drainage problems in the rice schemes of the Office du Niger (Mali) in relation to water management

This paper quantifies the impact of water management on the incidence of drainage problems. It is based on an empirical study in the rice schemes of the Office du Niger. The rice schemes face perpetual drainage problems at harvest, which incur increased production costs as well as production and/or quality loss. The rice schemes discharge water into natural depressions and their filling-up poses an ultimate bottleneck to the disposal of drainage water. Results demonstrate that the principal causes of drainage problems are the saturation of the drainage system with excess irrigation water and the insufficient maintenance of the collector drains. Once the collector drain is no longer saturated, maintenance of the tertiary drains becomes important, while the disparity in harvest dates between adjacent fields always aggravates the drainage problem. Since the benefits of individual efforts often accrue to neighbors or are dissipated throughout the entire drainage system, water management practices related to drainage should be tackled at the collective level using Water User Associations as a platform.