Assessing the Impact of Climate Change on Landslide Recurrence Intervals in Nakhon Si Thammarat Province, Thailand, Using CMIP6 Climate Models

Climate variability and climate change may influence the frequency and recurrence interval of landslides. Precipitation, as a main triggering factor of landslides, may be influenced by climate variability and climate change. Changes in precipitation may directly affect landslide frequency and recurrence intervals. Considering the influence of climate variability and climate change, the partial duration series method and critical rainfall threshold are combined with the simulated precipitation of Phase 6 of the Coupled Model Intercomparison Project (CMIP6) general circulation models (GCMs) to predict changes in future landslide recurrence intervals in Nakhon Si Thammarat Province, Thailand. The analytical results predicted changes in the landslide frequency over the next 20 years (2023 to 2042). SSP1–2.6 and SSP2–4.5 are adopted as future socioeconomic development scenarios. According to the predictions, the results showed that the return period of landslide occurrence in the future will be shorter than the return period of landslide occurrence in the historical period; moreover, the landslide recurrence interval will fluctuate greatly. The Nakhon Si Thammarat DWR meteorological station shows the most fluctuation in landslide recurrence intervals for SSP1–2.6. In addition, the Nakhon Si Thammarat meteorological Station experiences a significant decrease of approximately 35% in landslide recurrence intervals under SSP1–2.6. For SSP2–4.5, the Nakhon Si Thammarat meteorological station shows the most fluctuation in landslide return period. In addition, the Nakhon Si Thammarat meteorological station observed a decline in landslide recurrence intervals, with a reduction of approximately 40%. Hence, the frequency of landslides may increase in the future. A comparison between SSP1–2.6 and SSP2–4.5 revealed that SSP2–4.5 yielded lower landslide return periods.