Background: Chickpea is one of the major protein rich legume crops predominantly cultivated in North Interior Karnataka (NIK). The study aimed to determine water requirement of chickpea (variety BGD- 103) using CROPWAT model that helps in tapping the potential yields of the crop through proper irrigation management by the farmers of North Interior Karnataka (NIK), which consists of 12 districts with 88,361 km2 area. Methods: The crop was simulated by considering recommended practices of UAS, Dharwad across four dates of sowing from 01st October to 15th November at quarterly interval for the past (1991-2020) and projected period (2021-2050), and the decadal analysis was done for the past and projected climate. The analysed climate, crop and soil data were used for simulation using CROPWAT model. Results: The average crop evapotranspiration (ETc), effective rainfall (ER) and irrigation requirement (IR) under past climate (1991-2020) for NIK were 292.6, 57.4 and 245.9 mm, respectively. Decrease of 67 mm in ETc, 91.3 mm in IR and an increase of 40.8 mm in ER were observed under projected climate. Sowing early i.e., on 01st October under projected climate (2021-2050) simulated the lowest water requirement and irrigation requirement for all the 12 districts of NIK.