Space Technology and its Application in Disaster Management: Case Studies on Ecological Disturbance and Landmass Changes in Sundarbans

Abstract

Sundarbans, the largest single patch of mangrove habitation of the world is prone to large number of natural disasters. There is an urgent need to protect this precious resource to maintain the natural harmony between man and environment. To show the capability of remote sensing satellites, two case studies for Sundarbans have been presented. In the first study, assessment of ecological disturbance caused by some of the major cyclones of the last decade has been carried out in which Moderate Resolution Imaging Spectroradiometer (MODIS)-derived Land Surface Temperature and Enhanced Vegetation Index have been used to calculate MODIS Global Disturbance Index (MGDI). MGDI approach was used to assess the instantaneous ecological disturbance caused by cyclones, of different intensities, striking the mangroves at different phenological stages. The second study is about the landmass change and its periodicity during 1973 to 2017 using multispectral satellite data. Overall decrease in the landmass is in the order of 329.45 km2 during 1973 to 2017 @ 7.48 km2 year−1. However, the rate of erosion is highly variable over the years and varies between 1.62% (between 1973 and 1999) and as high as 4.50% (between 1973 and 2017). Based upon the net loss of landmass the islands are classified into 4 categories, viz. low (<10 ha year−1, including Kankramari, Sikarpur and Putni Island), medium (between 10 and 20 ha year−1, including Ghoramara, Jambudwip and Mahisani), high (between 20 and 30 ha year−1, including Sagar and Bulcherry), and very high (>30 ha year−1, including Dalhausi and Bangaduni).