Projection of near-future climate change and agricultural drought in Mainland Southeast Asia under RCP8.5

In order to plan for agricultural irrigation, the drought risk and amount of water needed for crops must be well studied. In this work, we apply the Standard Precipitation Index (SPI) and Crop Water Need (CWN) using input data from a fine-resolution Nested Regional Climate Model (NRCM) to assess the risk of future agricultural drought in Mainland Southeast Asia from 2020 to 2029. The NRCM was performed with resolutions of 60 and 10-km grid spacing for the present (1990-1999) and the future (2020-2029). The model employs initial and boundary conditions from the Community Climate System Model Version 4 (CCSM4) for meteorological variables. Two simulations, present-day (1990-1999) and future (2020-2029), were conducted under the Representative Concentration Pathway (RCP) 8.5 climate scenario. In general, the comparison between the NRCM predictions and observed data shows that the NRCM reasonably predicts precipitation and 2-m temperature with a high correlation of 0.89-0.98 and index of agreement (IOA) values ranging from 0.76 to 0.95. The future precipitation tends to decrease by (-1)-(1)mm/day, while the temperature will increase by up to 2-3 degrees C, which are favorable conditions for drought risk. Additionally, the SPI values between (-1.5) and 0 for both the dry and rainy seasons indicate a high possibility of drought events in the future. There seemed to be some evidence of drought risk in this region, but the calculation of CWN indicates that the region will remain relatively water rich for agriculture.