Water Delivery Performance of Canal Irrigation: A Case Study of Chalakudy River Diversion Scheme

The role of irrigation is important in mitigating the challenges involved in food production under the changing climate scenarios. Adequacy and equity in water distribution are the primary concern regarding the performance of any irrigation scheme. Conveyance efficiency and two adequacy indicators, namely, Relative Water Supply and Adequacy were used to evaluate the performance of Chalakudy River Diversion Scheme (CRDS) located in central Kerala, India, in the present study, Water withdrawal data collected from Irrigation Department, and data collected from field measurements of canal discharge and seepage loss were used in the study. Irrigation requirement of the canal command area was worked out using the FAO’s CROPWAT 8.0 software. The results revealed that the average annual irrigation demand of the CRDS command area is 46.90 Mm3 . Measured flow rate through the canal system showed that the flow decreases towards the tail end. Loss of water through seepage from the canal was high in the irrigation scheme due to the highly damaged condition of canal lining and poor maintenance. The CRDS canal system’s overall conveyance efficiency was found to be 51%. Based on Relative Water Supply and Adequacy Indicator, functioning of the irrigation scheme falls in the category of ‘fair’. Apart from proper repair and maintenance of canal system, conjunctive use of groundwater and canal water for irrigation is suggested towards the tail reaches to alleviate irrigation water inadequacy problems in the CRDS command area.