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Drought is a repetitive weather phenomenon marked by a slow beginning to increasing severity, and lasting an extended period depends on the water availability externally. Droughts encompass meteorological, hydrological, and agricultural categories which are all interconnected. Indian economy is more reliant on agriculture, relies more on agricultural output. The presence of agricultural drought significantly impacts on crop yielding, thereby influencing the regional economy. In this present study, relation between soil moisture and meteorological drought occurrence in all over India has been monitored through different remote sensing techniques. The drought assessment for meteorological and soil moisture has been done using two standardized drought measuring indices viz., Standardised Precipitation Index (SPI) and Standardised Soil Moisture Index (SSMI), respectively. The severity and persistence of these drought indices has been studied for 287 months (January, 2000 to November, 2023). Soil Moisture is acquired from a global data set by NASA; thus, processing has been done to bring them in same spatial subset. Since, drought detection needs processing for long temporal extent, the drought indices have been trained for 3 and 6 months as suggested as the best scale by many researchers. Using conditional probability and normalise scaling method drought resilience for 3 and 6 moths time scale has been assessed in this study. Alternatively, GLDAS-2 provides calculations for Terrestrial Water Storage (TWS), while GRACE data offers the Liquid Water Equivalent (LWE) variable. These datasets are utilized to develop the concept of Ground Water Storage (GWS), elucidating the quantity of groundwater retained across different areas of the Earth's surface. Lastly, the magnitude has been calculated for both SPI and GWS to establish a correlation assessment between them. As the temporal extent of GRACE and GLDAS is not same, it's important to carefully choose and focus on bands selection to ensure accurate results. Final interpretation of the outcomes has been shown on sub – hydro basin map of India, for a better vulnerability assessment and interpreting the agricultural impacts on those zones in particular.
Keywords: Drought, Standardised Precipitation Index (SPI), Standardised Soil Moisture Index (SSMI), Ground Water Storage (GWS), resilience.
