8. Re-Estimating the Crop Water Requirement (CWR)

Crop water requirements (CWR) are changing over a period due to climate change. The CWR derived with limited field data in the past using broad assumptions couldn’t represent the actual CWR to plan the water allocation in the present era of climate change. Reworking the crop water requirements (CWR), net irrigation requirements (NIR), and gross irrigation requirements (GIR) using scientific approach incorporating the climatic parameters has provided valuable insights into water allocation. CWR was re-estimated for different crops covering selected states in India. Comparing the NIR and GIR, at 60% efficiency level, only 66% more water is needed to meet the NIR, at 50% efficiency level, 100% more water is needed, at 40% efficiency level 150% more water is needed and at 30% efficiency level 233% more water is needed to meet the crop irrigation requirements indicating the importance of improving the project efficiency under growing water scarcity situations. Use of the re-estimated CWR is expected to alter the future irrigation demand scenarios in the country.