Evolution of meteorological drought characteristics over India using time-varying drought index

With approximately 28% of India's geographical area affected by droughts and a significant portion experiencing moderate to severe conditions, it is crucial to analyze these phenomena to assess their socio-economic impacts and develop effective policy responses. This study delves into the complexities of drought characteristics in India, emphasizing the need for advanced analytical methods to understand the evolving nature of droughts under changing climate conditions. From 1902 to 2013, the evolution of four essential drought characteristics: severity, depth, duration, and frequency has been examined across various climate zones. The analysis utilizes gridded precipitation datasets to compare outcomes from conventional Stationary Precipitation Indices (SPI) with a non-stationary, time-varying drought index aimed at offering a more sophisticated comprehension of drought dynamics and their socio-economic consequences. Furthermore, a non-linear trend analysis method has been implemented to identify the intrinsic complexities and non-linear correlations in drought data that conventional techniques tend to overlook.

The results indicate considerable geographical and temporal variations in drought dynamics. Central and southern India experience prolonged drought episodes, while areas like the Indo-Gangetic Plains and western India see shorter yet more severe droughts. The results further underscore the shortcomings of stationarity-based indices, which tend to overestimate drought severity and duration, especially in earlier decades. In contrast, the non-stationary index identifies subtle trends, indicating both gradual and sudden shifts in climatic patterns.

This study reveals critical hotspots of heightened drought risk, illustrating the increasing effects of hydroclimatic extremes in areas predominantly dependent on agriculture and monsoonal precipitation. By enhancing the accuracy of drought assessments and their spatial-temporal variability, the need for region-specific climate adaptation and mitigation strategies has been highlighted. The findings thereby contribute to the broader discourse that underscores the necessity of integrating evolving climate dynamics into future drought projections to tackle the increasing problems posed by hydroclimatic extremes in a rapidly changing environment.