Ground truth mapping with multi-temporal earth observation data in ESA CloudTool box: A case of Kerala flood event occurred in 2018

摘要

Kerala received an extensive rainfall during Jul-Aug 2018 which led to disastrous flood condition in many places of Kerala state. Optical Remote Sensing (RS) images acquired during the flood event with low cloud cover are used for ground truth mapping. Earth Observation (EO) images from three satellite, i.e., Sentinel-2, Landsat-8 and World View-3 are used. Two indices, i.e. Green Normalized Difference Vegetation Index (GNDVI) and Modified Normalized Difference Water Index (MNDWI) are used to analyze the flood pattern in the study area. A hybrid approach involving thresholding the indices combined with manual digitization is carried out for ground truth flood area extraction. Here, we used the CloudToolbox service provided by the European Space Agency (ESA) to process and analyze the Earth Observation (EO) data. From the images, it is quite evident that the flood water was increased from 12 Aug - 22 Aug 2018 and started receding by 27 Aug 2018.