Climate Change Impacts on Rice Farming in Thailand’s Bang Pakong River Basin: an analysis Using Cropwat and DSSAT Models

Abstract

Rice production is associated with water, food security, and livelihood, and it is being affected by climate change. Additionally, rice paddies can emit greenhouse gases back into the atmosphere. This study uses the Cropwat and DSSAT models to investigate the impacts of climate change on irrigation water requirements and rice yields in the Bang Pakong River Basin, Thailand. The simulation results were then used to calculate rice water productivity and farmer income. Moreover, methane emissions from rice fields were also calculated using the IPCC equations. The study uses outputs from three CMIP5 Global Climate Models (EC-Earth, MPI-ESM-MR, and HadGEM2-ES) downscaled under RCP4.5 and RCP8.5 scenarios using two Regional Climate Models (RegCM4 and RCA4). The results indicate that, when comparing the baseline period (2000–2023) with the far future (2075-99), irrigation water requirements for rice under RCP4.5 and RCP8.5 are projected to change between − 8.6 and 9.7% and 1.7–15.3%, respectively. Rice yields under RCP4.5 and RCP8.5 are expected to change between − 4.3% to -3.3% and − 11.4% to -2.0%, respectively. Farmer income under RCP4.5 and RCP8.5 are expected to change between − 12.7% to -9.0% and − 34.4% to -5.5%, respectively. Biophysical water productivity under RCP4.5 and RCP8.5 are projected to change between − 16.7 and 5.5% and − 25.0% to -10.5%, respectively. Economic water productivity under RCP4.5 and RCP8.5 are projected to change between − 25.7% to -2.9% and − 46.8–5.9%, respectively. Calculated methane emissions from rice paddies are estimated at 134 kg/ha. These results demonstrate the negative impacts of climate change on rice farming. The information obtained from this study is helpful in developing adaptation strategies to mitigate these impacts.