Assessment of rice yield and irrigation requirement simulated by crop model in paddy fields under climate changes

Abstract

 This paper uses the iGAEZ (improved Global Agro-Ecological Zones) model for simulating rice yield in the paddy fields at Matsuyama. We estimated the rice yield and net irrigation requirement for 2007-2011, 2071-2100 using the present and future climate datasets obtained by a statistical downscaling model (SDSM) for CGCM model under SRES A1B and A2 emission scenarios, NCEP reanalysis data, and AMeDAS observed data. Results indicate rice yield in field have increased by more than 30% in the future under the all scenarios, which have high CO₂ concentration. In contrast, it is found that reduction in rice transpiration is about 12%. In addition, because net irrigation requirement will likely increase by 28% under A1B, and 36% under A2 due to precipitation decreasing in the future, water withdrawals from the river will be more increased in the future.