Abstract

Cyclonic catastrophes frequently devastate coastal regions of Bangladesh that host around 35 million people which represents two-thirds of the total population. They have caused many problems like agricultural crop loss, forest degradation, damage to built-up areas, river and shoreline changes that are linked to people’s livelihood and ecological biodiversity. There is an absence of a comprehensive assessment of the major cyclonic disasters of Bangladesh that integrates geospatial technologies in a single study. This study aims to integrate geospatial technologies with major disasters and compares them, which has not been tried before. This paper tried to identify impacts that occurred in the coastal region by major catastrophic events at a vast level using different geospatial technologies. It focuses to identify the impacts of major catastrophic events on livelihood and food production as well as compare the impacts and intensity of different disasters. Furthermore, it compared the losses among several districts and for that previous and post-satellite images of disasters that occurred in 1988, 1991, 2007, 2009, 2019 were used. Classification technique like machine learning algorithm was done in pre- to post-disaster images. For quantifying change in the indication of different factors, indices including NDVI, NDWI, NDBI were developed. “Change vector analysis” equation was performed in bands of the images of pre- and post-disaster to identify the magnitude of change. Also, crop production variance was analyzed to detect impacts on crop production. Furthermore, the changes in shallow to deep water were analyzed. There is a notable change in shallow to deep water bodies after each disaster in Satkhira and Bhola district but subtle changes in Khulna and Bagerhat districts. Change vector analysis revealed greater intensity in Bhola in 1988 and Satkhira in 1991. Furthermore, over the years 2007 and 2009 it showed medium and deep intense areas all over the region. A sharp decrease in Aus rice production is witnessed in Barishal in 2007 when cyclone “Sidr” was stricken. The declination of potato production is seen in Khulna district after the 1988 cyclone. A huge change in the land-use classes from classified images like water body, Pasture land in 1988 and water body, forest in 1991 is marked out. Besides, a clear variation in the settlement was observed from the classified images. This study explores the necessity of using more geospatial technologies in disastrous impacts assessment around the world in the context of Bangladesh and, also, emphasizes taking effective, proper and sustainable disaster management and mitigation measures to counter future disastrous impacts.

Highlights

  • The Normalized difference vegetation index (NDVI), NDWI and NDBI were performed on the bands of pre- and post-disaster images

  • This study considered pre- and post-disaster satellite images for the given years of cyclone incidence

  • NDVI indicates the changes in vegetation, while NDWI and NDBI represent variance in the waterbody and built-up areas

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Summary

Introduction

A severe cyclone strikes the country every 3 years [41] It is heavily impacted by catastrophes because of geographic factors like its location, trivial continental shelf, almost sea-level geography of the coastal land and the high-density population [18]. These disasters cause heavy loss to life, property, biodiversity, livestock and most importantly to agriculture that create social and economic losses to the affected communities. Agricultural and built-up areas are in a more vulnerable zone because of direct contact by cyclonic turbulence [37] These disasters cause severe distortion socioeconomically by affecting land transactions, livestock damage, destruction of built-up areas and causing debt to the local people for postdisaster recovery [34]. Total 1% of the global cyclone hits the Bangladesh coasts, but it experiences 53% of the global fatalities of the cyclone [26]

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