More crops whilst saving drops using an optimization model-A case from Bangladesh*

This study aims to determine the optimal use of irrigation water and irrigable area in the Karnafuli Irrigation Project (KIP) of Bangladesh by developing an optimization model using linear programming. The project consists of two units, namely, Halda and Ichamati, and the units are fed with Karnafuli river water. Required data were collected from several government offices and from the CMIP5 model. Considering existing cropping practice, irrigation supply, and future climate, the optimization model was run for four different scenarios. Climate change-induced effects appeared as non-significant in the optimization. In the Halda Unit, the existing cropping intensity is 136%, whereas optimal cropping intensity can be increased up to 200%. In the Ichamati Unit, optimal cropping intensity for all scenarios is in between 175% and 200%, where the existing intensity is 150%. An increase in cropping intensity in both the units in optimal scenarios results in higher benefits. At the same time, the implementation of the optimal situation in the KIP can save 20% of the diverted water, indicating the possibility of greater yields and subsequent greater benefits even if the existing water supply is saved. The outcomes of the research have been communicated to the regional extension office for implementation.