Evaluation of Water Delivery Performance of Nkhafi Irrigation Scheme in Dowa District, Malawi, Africa

Abstract

This study evaluated the water delivery performance of Nkhafi irrigation scheme based on adequacy, water delivery efficiency, equity, dependability and irrigation efficiency. Primary data were collected from field measurements, scheduled interviews, group discussions and use of a structured questionnaire. CROPWAT 8.0 computer model was used to determine crop water requirements and irrigation requirements. The results revealed that adequacy, water delivery efficiency, equity, dependability and overall water delivery performance were (0.74; 0.82), (0.70; 0.80), (0.15; 0.20), (0.11; 0.21) and (0.80; 0.80) for 2017 and 2018 seasons respectively. The scheme overall irrigation efficiencies were 20% and 25% for 2017 and 2018 respectively. These findings revealed that scheme users failed to deliver adequate and dependable water in an effective manner in both growing seasons. This occurred due to insufficient water supply, poor irrigation scheduling, lack of adequate knowledge and skills in operating and rehabilitating hydraulic structures, siltation and water losses through seepage in canals. Therefore, it is recommended that major maintenance works need to be done along the whole canal network in order to achieve good overall water delivery performance. Furthermore, farmers need to be trained in water management, sustainable agricultural production practices, operation and maintenance of irrigation structures. The study has provided an insight on the status of the scheme hence encouraging scheme users to improve water delivery performance.