Spatiotemporal analysis of historic and future drought characteristics over a monsoon dominated humid region (kerala) in india

Drought manifests as a devastating natural event and Kerala in India has experienced frequent drought in the recent past, despite being in a tropical monsoon climate region. This study primarily concentrates on the analysis and future projection of meteorological drought events in Kerala using the Standardized Precipitation Index (SPI) for different timescales (3-month, 6-month, and 12-month). For the analysis of historic drought events, Global Land Data Assimilation System (GLDAS) gridded rainfall data was used. Mann- Kendall and Sen's slope estimator was employed for evaluating the trend in the SPI time series and the persistence of the trend was analysed using the Hurst exponent. The linkage between meteorological drought and Sea Surface Temperature (SST) anomalies in the Nino 3.4 region and the Indian Ocean was also studied. Results from this study indicated that a recent extreme drought event occurred in the year 2016 and is more affected in northern parts of Kerala. The results of trend analysis show that a statistically significant decreasing trend in SPI values was identified for more than 70% of the grid points. Correlation analysis of SPI values and SST anomalies indicate a weak lagged negative correlation with Nino 3.4 and a weak lagged positive correlation with the Indian Ocean region. Future projection of SPI values under two climate change scenarios (SSP1-2.6, SSP5-8.5) from Coupled Model Intercomparison Project Phase 6 (CMIP6) reveals the occurrence of recurrent drought events in the near (2021-2050) as well as the far future periods (2051-2100). Moreover, a decreasing trend in SPI values was observed in the near future under SSP5-8.5 for 3-month and 12-month time scales. For SSP1-2.6, projections indicate that extreme drought years are observed in 2046 and 2089, and in the case of SSP5-8.5 scenario, extreme drought years are anticipated in 2034 and 2061. The results obtained from this study will help in identifying the regions that need more attention in drought mitigation and hence proper planning can be adopted in those areas.