Enhancing Efficiency of the Minipe Left Bank Canal Irrigation System: A Strategic Approach

Minipe left bank canal faces a head-tail water imbalance due to insufficient water availability and inefficiency in water distribution. To address this issue, Minipe anicut is raised by 3.5m. Though ample water could be released, irrigation water would not be dispersed adequately along the canal due to mis-usage and mismanagement. The study aims to establish an operational pattern for the canal to deliver adequate water to the entire command area during both the Yala and Maha seasons. Simulation models were used to model the canal's operational pattern, including inflows and irrigation demands. Catchment areas, which bring water to the Minipe Left Bank canal, were delineated using ArcGIS software, and inflows were estimated using HEC-HMS software. Crop water requirements were estimated using CROPWAT program. A system simulation model developed usingWEAP software was used to simulate irrigation system operation. Nine management scenarios were evaluated, including introducing new cropping patterns, shifting sowing dates, increasing Minipe anicut discharges, and reducing the command area. The study found that introducing a 70% paddy crop pattern, advancing the sowing date by two weeks, and raising the Minipe anicut discharge by 15% significantly reduce unmet demands. Implementing these improvements could result in a 75% reduction in unmet demand.