Long-term trends in land erosion and accretion within the Meghna-Tetulia-Feni River Estuary (1973–2023)

Abstract

A comprehensive comprehension of the mechanisms governing land erosion and accretion is of utmost importance in the pursuit of sustainable management strategies for estuarine environments. The present study aims to examine the enduring patterns of land erosion and accretion in the Meghna-Tetulia-Feni River Estuary in Bangladesh over a span of five decades, from 1973 to 2023. The study utilizes a dataset comprising 24 Landsat images captured during six significant years (1973, 1980, 1990, 2000, 2010, and 2023). The research employs both supervised and unsupervised classification techniques to demarcate the estuarine landscape into five distinct categories. These categories are subsequently reclassified into land and water classes for further analysis. The results suggest that there was a total land gain of 1406.91 km2 throughout the fifty-year period, with an average yearly increase of 28.14 km2. Significantly, the period spanning from 1980 to 1990 witnessed a notable increase in the net accretion rate, reaching a peak of 81.10 km2/year. Consequently, the total accretion during this period amounted to 1183.78 km2. In contrast, it is expected that the time span between 2010 and 2023 will experience a substantial decrease in land area, estimated to be roughly 705.73 km2. Given the significant geomorphological transformations and their wider economic and ecological consequences, this study proposes the implementation of an adaptable and flexible management approach that prioritizes the sustainable utilization of land and water resources in the Meghna-Tetulia-Feni River Estuary.