Impact of Climate Change on Crop Water Requirement of Rice in Central Zone of Kerala : An Assessment Using CROPWAT Model

The study was to investigate the possible impact of climate change on crop water requirement of rice in central zone of Kerala during different time period and future climates 2030, 2050 and 2080. Climate data for the years 2030, 2050, 2080 were collected from MarkSim DSSAT weather file generator under Representative Concentration Pathways (RCP) 4.5 scenarios. The crop water requirement of rice for different seasons during these periods was predicted using CROPWAT 8.0 model by assuming same crop management practices for all these years. It was found out that evapotranspiration, effective rainfall and irrigation requirement showed different trends in different seasons during 2030, 2050, and 2080. In virippu season percentage deviation of irrigation requirement from that of 2021 value was found to be 180. 7, 179.0, 181.0 for the years 2030, 2050, 2080, respectively. In mundakan season percentage deviation of irrigation requirement from that of 2021 was found to be -40. 4, -41.1, -29.8, respectively. In puncha season percentage deviation of irrigation requirement from that of 2021 was found to be -5.4,-5.3,-3.6 for the years 2030, 2050, 2080, respectively. The increase in irrigation requirement during virippu season in future compared to 2021 might be due to decrease in effective rain fall during this period and the decrease in irrigation requirement in future compared to 2021 during puncha and mundakan season might be due to increase in effective rainfall during this period. Considering the probability of increase irrigation requirement during virippu season in future, proper water management strategies should be adopted to sustain farmer’s income in addition to current irrigation management practices.