Long-term assessment of crop water dynamics and irrigation dependency for selected major Kharif crops under climate variability using the CROPWAT Model in the Araniar command area, Andhra Pradesh, India (1990–2024)

A comprehensive understanding of crop water requirement (CWR) is crucial for improving irrigation practices, irrigation scheduling, and optimizing water usage. In the present study, reference evapotranspiration (ET0), CWR, and net irrigation requirement (NIR) for Kharif crops were estimated for the Araniar command area, Andhra Pradesh, India, for the period 1990–2024 using CROPWAT 8.0 model. The Fixed percentage, dependable rain empirical formula, USDA Soil Conservation Service and Penman–Monteith method was employed to determine effective rainfall and average daily reference evapotranspiration, respectively, resulting in a value of 4.91 mm/day. The study area’s effective rainfall was estimated at 926.6 mm, accounting for 74.9% of the total annual rainfall of 1235.9 mm. Utilizing the crop coefficient approach, the CWR for Paddy, Groundnut, and Bajra was estimated at 801.30, 531.70, and 380.40 mm, respectively. The corresponding net irrigation requirements were 431.8 mm for Paddy, 74.3 mm for Groundnut, and 44.2 mm for Bajra. The irrigation dependency ratio, indicating the proportion of CWR not met by effective rainfall, were found to be highest for Paddy (53.9%), followed by Groundnut (14.3%) and Bajra (11.6%). These findings highlight the significant variation in water dependency among crops and offer valuable insights for the efficient planning and sustainable management of irrigation resources in the Araniar command area.