EVALUATION AND OPTIMIZATION OF IRRIGATION TECHNIQUES TO REDUCE WATER LOSSES AND IMPROVE AGRICULTURAL PRODUCTIVITY: CASE OF DANOUNA IRRIGATION SCHEME IN CHAD

Abstract

This study focused on the evaluation and optimization of irrigation techniques to reduce water losses and improve agricultural productivity in the Danouna irrigation scheme, located in the Hadjer Lamis region of Chad and benefiting from the water resources of the Chari-Logone River. The main aim of the study was to identify the inefficiencies of the current irrigation system in terms of rational water use and agricultural yield, and to propose solutions adapted to the local context for more sustainable management of the resource. The analysis carried out in the Danouna irrigation scheme, combining literature review, field surveys and measurements with simulations using CROPWAT model, revealed an over-irrigation of around 86% compared to the real needs of rice. This wastage was mainly due to an inappropriate irrigation schedule, a lack of tertiary canals and losses through deep percolation and infiltration in unlined secondary canals. As far as agricultural productivity is concerned, despite these inefficiencies, the average yield observed in the Danouna perimeter is around 6 tons per hectare, which is still higher than the regional average but below optimum potential. Analysis of water productivity, estimated at around 0.27 kg/m³, points to considerable room for improvement through more rigorous irrigation management and more efficient farming practices. On this basis, the study proposed several avenues for optimization: a precise readjustment of the irrigation schedule according to the critical growth stages of the rice crop, the modernization of hydraulic infrastructures, notably through the rehabilitation of secondary canals and the much-needed construction of tertiary canals, and the adoption of better agricultural practices, including raising farmers' awareness of good irrigation practices. This work has highlighted a number of methodological limitations, particularly with regard to data availability and reliability. As a result, further research integrating advanced tools such as soil moisture sensors or remote sensing is required. Specific recommendations were also made to ensure sustainable management of the Danouna irrigated perimeter.