A synergetic approach for multidimensional drought assessment in the Indian agro-climatic zone using coherency, propagation and AHP techniques.

Drought is one of the most detrimental natural calamities to the economy. Despite its significant consequences, the evolution from meteorological to agricultural and hydrological droughts still needs to be explored. A thorough investigation was carried out in India's eastern hills and plateau region to determine the extent of drought's impact through indices. Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), Standardized Soil Moisture Index (SSMI), and Standardized Streamflow Index (SSI) were analyzed to delineate meteorological, agricultural, and hydrological droughts across the region using precipitation, temperature, soil moisture, and streamflow data comprising of the 35 years (1987-2021) from 24 stations. Analytic Hierarchy Process (AHP) was employed with Geographic Information System (GIS) techniques for combined drought indicator. The findings show that compared to other indices, the maximum weightage is given to meteorological drought indices (SPI and SPEI). The combined drought index (CDI) resulted from 39.1% of SPI, 27.6% of SPEI, 19.5% of SSMI, and 13.8% of SSI. The AHP technique made it easier to generate maps. These maps categorize the area into five degrees of vulnerability, from severe drought to normal conditions. The propagation duration from the onset of meteorological drought to the emergence of agricultural and ultimately hydrological drought was explored. The propagation time of hydrological drought after meteorological drought is longer compared to agricultural drought. Additionally, wavelet coherence analysis investigated the interaction of meteorological drought with agricultural and hydrological drought in the region. Temporal assessments of the spatial extent of drought across the study area were also conducted, offering crucial details about the drought's regional and temporal pattern. This multidimensional method provides a thorough learning of the dynamics and sensitivity of drought in the eastern hills of India and the plateau region. This is helpful for the implementation of targeted mitigation and adaptation strategies to reduce the adverse impacts of drought.