Assessment of Agricultural Drought Vulnerability in Tamil Nadu Using MODIS NDVI, NDWI and VSDI

Abstract

Agriculture continues to be sensitive to drought conditions despite the technological developments in weather analysis and crop management in Tamil Nadu. Agricultural drought vulnerability is defined as exposure, sensitivity and adaptive capacity of an agricultural area to the situation of inadequate soil moisture availability. Geographic information systems-based assessment of agricultural drought vulnerability map that was created through the development of a numerical weighting scheme helps to evaluate the drought potential of the classes within each factor that can lead to mitigation-oriented drought management. The severity and extent of drought in Tamil Nadu state is believed to be the result of aberrations in rainfall, overexploitation of ground water, lower reservoir levels and crop stress conditions. Hence in the present study, the agricultural drought is assessed for Tamil Nadu from 2006 to 2018, using MODIS’s Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI) and Visible and Shortwave Infrared Drought Index (VSDI). From these qualitative approaches of assessing the agricultural drought vulnerability, the values are calculated, mapped and categorized into five classes: Very slightly vulnerable, Slightly vulnerable, Moderately vulnerable, Highly vulnerable and Very highly vulnerable, for all the above-mentioned indices. From the results, top five acute drought-prone districts in Tamil Nadu, particularly the area under highly vulnerable and very highly vulnerable classes are identified for all three indices. In the study area, different areas are differentially exposed to drought and have different levels of vulnerability. This assessment of agricultural drought vulnerability would help in planning and preparedness in the study area. In addition, recommendations are also put forward for consideration.