MANCO 20th :Technology And Innovation In Tertiary Canal And On Farm Structures And Water Delivery For Sustainable And Efficient Water Management In Small Holder Rice Production

Mohd Yazid bin Abdullah* and Mohd Amin bin Mohd Soom**


Irrigation Modernization is crucially needed nowadays to increase water, land, energy and labour productivity as to face the stiff competition for the limited resources and to meet the challenges for producing sufficient food for increasing population. Most of the irrigation infrastructures for rice production in Malaysia were designed and constructed more than 30 years ago to meet the irrigation and drainage requirement then. There are many changes which have occurred in rice industry and rice cultivation practices since then. Three structures in the tertiary canal and on-farm were designed and evaluated in this study: (1) field offtake to deliver water from tertiary canal to paddy fields; (2) the tertiary canal water level regulator or check structure and (3) field drainage outlet control structure. The functionality, flexibility, accuracy and suitability of these structures are the main criteria in their design consideration, and the evaluation carried out subsequently refers to those criteria. The laboratory and field evaluation were carried out to verify the performance of the structures and modifications to the developed structures were introduced to improve water delivery quality in tertiary canal and paddy field. The performance improvement of the existing tertiary canal system was studied for excellent water delivery service to support various farm activities and their scheduling, rainwater harvesting and control of chemicals in the paddy field. The water delivery management model was developed for four modes of irrigation supply, viz. presaturation, second flooding, crop growth stage water delivery and the termination of irrigation and drainage control prior to harvesting. The results of the field evaluation conducted in the pilot project site on the developed structures and water delivery management model provide encouraging results in improvement of water delivery service in the tertiary canal and on farm water management in term of reliability, equity and flexibility together with more accurate flow measurement. The application efficiency was also increased due to water saving through the faster presaturation and shorter irrigation delivery. A more efficient farm and irrigation management through the improved delivery model and the associated structures was obtained. The ability to maintain standing water depth in paddy fields without relying on the overflow of water through field drainage outlet pipes during supplementary delivery enabled successful rain harvesting, storing it in the paddy fields and its use in the paddy fields. The capability to keep appropriate standing water depth in the paddy fields has also reduced the possibility of flow of chemicals from paddy fields to the drains through run off. While providing storage for rainfall harvesting paddy field is also function as flood detention and groundwater recharge. The developed water delivery management model with utilization of the newly developed structures reduces the farmers’ frequency in attending the offtake to meet the paddy field standing water depth target. The most appropriate supplementary irrigation delivery method suggested for the tertiary canal is continuous supply whole day supply through the utilization of the developed flexible field offtake based on estimation of daily or weekly water utilization in the paddy fields. The field tests verified that this delivery method successfully reduced perturbation in tertiary canal and at the same time maintained the targeted standing water depth in paddy fields within the acceptable range.

*Senior Assistant Director, Irrigation Unit, BPSP. ** Professor, University Putra Malaysia