Assessment of Agricultural Drought Severity in the Southern Agroclimatic Region of Tamil Nadu using Remote Sensing-Based Combined Drought Index

Drought is one of the significant issues of socio-economic development that causes severe impacts on health, agriculture, economies, energy, and the environment. Hence, it is vital to map and monitor agricultural droughts to achieve sustainable management of land-soil-water resources, particularly in the semi-arid agroclimatic regions. In the present study, the dynamic status of drought is estimated by analysing the six remote sensing-derived drought indices, namely Normalized Difference Vegetation Index (NDVI), Land Surface Temperature (LST), Standardized Precipitation Evapotranspiration Index (SPEI), Vegetation Condition Index (VCI), Vegetation Health Index (VHI), Soil Moisture Index (SMI) calculated for the years between 2016 and 2022 to develop a Combined Drought Index (CDI), using Principal Component Analysis (PCA) technique in the Southern Agroclimatic region of Tamil Nadu which is known for agricultural production being affected by frequently droughts. We found that the majority of the study area experienced severe to extreme drought stress in the years 2016 (61%), 2019 (51%), and 2022 (49%), especially Ramanathapuram, Sivaganga, Virudhunagar, Thoothukudi, and Pudukkottai were worst affected. For validation, the correlation coefficient between CDI and Standardized Precipitation Index (SPI) was evaluated for the drought-hit years (2016, 2019, and 2022), and the results showed a relatively positive correlation, indicating that the area had been highly vulnerable to drought conditions. Hence, decision-makers and the management community can use this index to monitor, assess, manage, and reduce the drought risk more accurately at the local to global level and to support agricultural drought management practices.