Estimation of Erosion–Accretion Using Remote Sensing Approach: A Case Analysis on Teknaf Coastline

Abstract

Bangladesh is bounded by the Bay of Bengal on the south with a highly irregular deltaic coastline of about 580 km. Teknaf Upazila of Cox's Bazar District is in the southern part of Bangladesh and is being continually affected by sea-level rise, cyclones, and recurring effects of high waves during storm surges, which have caused erosion in this coast. Moreover, the coast morphology, tide, and high-velocity longshore current also act as important agents for sediment transportation. As a result of these natural processes, erosion and accretion are common phenomena of the Teknaf coastline. This study conducts a systematic assessment of shoreline shifting of the Teknaf coastline using satellite data ranging from 1989 to 2019 by Remote Sensing and GIS technique. The impact of some major cyclones (1991 Cyclone, SIDR, and AILA) on coastal erosion–accretion has also been addressed in this study. The analysis of the results showed that erosion on this coast becomes high generally after every cyclone and storm surges. The erosion rate was found to be 5.654 sq. km. / year after the 1991 cyclone which is also highest in the historical period of 30 years between 1989 and 2019. On the other hand, the maximum accretion rate was found to be 6.366 sq. km./year between the years 2002 and 2003. Around this time period, no major cyclones were recorded to hit the Teknaf Coastline directly. Moreover, erosion governed for first 10 years (1989–1999), then accretion governed for next 5 years (1999–2004), later erosion governed for next 10 years (2004–2014), and finally after 2014, the accretion started to increase. The study findings can be applied by policymakers and administrators to develop effective mitigation plans, minimize coastal hazards related impacts, and plan integrated coastal zone management (ICZM) to achieve sustainable coastal zone development.