Modelling Paddy Water Demand and Irrigation Efficiency Using CROPWAT 8.0 for Sustainable Agriculture in Sundargarh District, India

ABSTRACT Declining water resources and rising food demand require improved water use efficiency. In this study, paddy water requirements were comprehensively assessed for the Sundargarh district, India, during 2000–2022 using the CROPWAT 8.0 model. Key parameters, including crop water requirement (CWR), net irrigation requirement (NIR), reference evapotranspiration (ET o ) and crop evapotranspiration (ET c ), were estimated. ET o was calculated using the FAO Penman–Monteith method. The results indicate that effective rainfall contributed significantly, with empirical determination meeting 73% of consumptive use. Seasonal variations showed higher CWR in Rabi (911.9–1294.3 mm) than in Kharif (550.5–1041.7 mm). Notably, 34% (Kharif) and 37% (Rabi) of NIR were applied during nursery/land preparation, with irrigation scheduled at 9‐day intervals. An overall 4% increase in NIR was observed during Rabi, and the maximum flow rate was 8.16 L/s/ha in 2000. Model‐derived yield loss showed no reduction due to ET c deviations in Kharif, but a significant 15% reduction occurred during Rabi, with a 29% change in ET c at the late stage using the FAO‐56–based yield response factor ( k y ). These findings provide valuable insights for irrigation authorities to design efficient, sustainable paddy water management strategies in the region.