Assessment of LULC Change During the Post-polderization Period Using GIS and Trend Analysis and Its Influence on Societal Structure in Southwest Coastal Bangladesh

The coastal region ofGeographic Information System (GIS) Bangladesh, especially the southern part, is prone to various kinds of natural disasters due to its geolocation and low-lying landscapesLandscape. Different natural disasters, predominantly riverine, are very common phenomena that have created a massive impact on the life and livelihood of the coastal inhabitants. To lessen this vulnerability, the Government has made significant investments in coastal infrastructure development such as the installment of polders in 1960, which is one sort of infrastructural development (i.e., embankments). In consequence, polderization has resulted in a major shift in different spheres of the social structure of the surrounding locality followed by massive land use and land cover change. This paper presents the influence on the social structure of land use and land cover change during the post-polderization period from 2000 to 2020 in polder 25 in southwestern Bangladesh. An unsupervised classification approach was used to classify the five time-series Landsat satellite images (Landsat 5–8) into six classes: waterbody, aquaculture, mixed culture, agriculture, yellow area, and vegetation. NDWI operation was also carried out to properly delineate the alteration of the land–water interface along with the timeframe. Furthermore, a survey on households selected by purposive sampling was conducted considering their age structure above 40 years in order to thoroughly investigate the influence of LULC changes on social structure (social institution, social status and roles, and social groups). Between 2000 and 2020, the extent of mixed culture increased by 390.91%. Within this period, the dominance of agriculture and vegetation reduced to 64.46% and 40.85%, respectively. Due to the progressive rise of urban development, yellow area (built-up area and barren land) showed an increase of 63.23% and waterbody decreased by 29.67%. Mann–Kendall trend test result depicted there is a trend present in change of waterbody (p = 0.014 < ɑ), vegetation (p = 0.014 < ɑ), agriculture (p = 0.014 < ɑ), and mixed culture (p = 0.014 < ɑ). No trend is found in aquaculture (p = 0.327 > ɑ) and yellow area (p = 0.142 > ɑ).