Strategies for Crop‐Based Scheduling of Secondary Canals: Case Study of Mirpurkhas Subdivision, Pakistan

The present study was conducted in the Mirpurkhas subdivision within cut Jamrao canal command of the Nara Canal Area Water Board. Crop water requirements were evaluated under different irrigation methods. The Mehran model was used to calculate irrigation and crop water requirements, while the crop‐based irrigation operation (CBIO) model was used for secondary canal scheduling/rotation. To calculate irrigation demand, losses in the irrigation network and field application losses were measured. Besides CBIO, scheduling of canals was verified by real‐time scheduling on the basis of weekly crop irrigation demand by simple programming in Excel. The canal scheduling designed on the basis of the CBIO model suggests that all distributaries, minors and direct outlets would be closed for 6 weeks in the kharif season, whereas they will be closed for 7 weeks at premeditated time intervals during the rabi season. The real‐time canal scheduling indicated that the numbers of open and closed weeks are almost same as scheduled by the model; however, certain adjustments have been made to synchronize the closed weeks with annual closure in rabi for canal maintenance. The results further revealed that by implementing canal scheduling in the area, 34 and 40% of irrigation water can be saved in kharif and rabi, respectively.