Comparative Analysis of SPI and SPEI as Meteorological Drought Indices in the Highland Region of Kerala

Drought is a disastrous natural phenomenon that can devastate agricultural production and cripple the regional socioeconomic well-being. It will occur due to insufficient rainfall for a prolonged period of time, resulting in water shortages for various activities. Therefore, the analysis and future projection of drought events are necessary to adopt the appropriate mitigation activities. This study evaluates the performance of the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) for assessing drought in the highland region of Kerala at different timescales. The study area is Wayanad district which is located in the northeastern part of Kerala, linking the eastern ghats and western ghats. For the analysis of drought indices, GLDAS gridded precipitation and temperature data were used over a span of 67 years. Trend analysis of SPI and SPEI values was detected using the Mann-Kendal trend test and the Sen’s slope method. The study findings revealed that the study area is subjected to frequent droughts of varying severity on the timescales considered. The years 2016 and 1983 witnessed notable drought events, effectively demonstrated by the two indices. Additionally, a decreasing trend in SPI and SPEI values was detected at all the gridded points in the study area which indicates an increasing severity of drought events. The results obtained from this study will help identify the regions that require more attention and help the authorities to take appropriate measures.