Development of a Planting Date Estimation Model and Assessment of Climate Change Impacts in Northeast Thailand

Abstract

 In Northeast Thailand, where 60% of the nation's rice fields are located, the majority of rice cultivation depends on precipitation, making it highly sensitive to changes in weather patterns. Given this background, this study introduces a model developed to estimate rice planting dates and areas using detailed daily weather data, topographical information, and land usage patterns. This approach sets itself apart from previous research by integrating daily precipitation fluctuations to estimate the planting dates. Model calibration was conducted using observational data from 2005, resulting in errors of 8.66%. Model validation was conducted using data from 2004 and the error was 13.9 %, indicating a reasonable replication of observed values. The model was employed to analyze the impact of variations in precipitation from 1981 to 2017 on planting dates. The results show considerable shifts in planting dates, characterized by a trend towards increased variability and postponement in planting. These adjustments are primarily attributed to changes in precipitation at the onset of the rainy season. Furthermore, by inputting future precipitation data, we estimated the future planting dates. The results showed that the trend of delayed planting dates would continue in the near future and would shift to earlier dates in the distant future.