Vegetation stress as chief indicator for detection of hydrocarbon microseepage in regions of north-eastern India

Hydrocarbons are of significance for economic and environmental standpoints. Hydrocarbon microseepage alters the surface properties of land. Here, the detection of potential hydrocarbon microoseepage zone based on vegetation stress is carried out in the north-eastern Indian states of Assam and Meghalaya. A weighted overlay model, fed by 11 spectral wide and narrow band vegetation indices (VIs), is used to determine the effective VIs for detecting vegetation stress. Mineral alteration indices are also employed as proxies to detect potential hydrocarbon microseepage sites. Mineral alteration zones exhibiting vegetation stress are speculated to be potential hydrocarbon microseepage sites. VIs such as Red Edge Normalized Difference Vegetation Index (RENDVI), Normalized Difference Vegetation Index (NDVI), Lichtenthaler Index 1 (LIC1) and Simple Ratio Index (SRI) are more effective in detecting vegetation stress as they are sensitive to minor variations in chlorophyll content. The predominant vegetation stress is detected in south-east region of the study area in Jowai around Jaintia hills. The mineral alteration indices confirms that it is a potential hydrocarbon microseepage zone. Thus, remote sensing data can serve the dual purpose of fuel resource exploration and pollution source detection at once being cost effective, hazard free and convenient.