Assessment of Land Cover Dynamics, Land Surface Temperature, and Heat Island Growth in Northwestern Bangladesh Using Satellite Imagery

The study examined the spatiotemporal variability of land use/land cover changes (LULC), land surface temperature (LST), and heat island (HI) in northwestern Bangladesh. Landsat images were used for evaluating LULC, LST, and HI for the years 1990, 2002, 2014, and 2018. Unsupervised and index-based classification approaches were used for mapping LULC. The mono-window algorithm was employed to identify the spatiotemporal variability of LST and HI. The analysis suggested that water bodies, forests, and bare land dwindled during these 28 years with an average of about 40%, 70%, and 45%, respectively. Agricultural land had been expanded from 1990 to 2002 and gradually stabilized in recent decades. Settlement areas increased alarmingly from 1990 to 2018. The water bodies, forests and bare lands were reduced due to the widening of agricultural land and rapid growth of urban area. The extents of the HI were found to be spreading out and became most extensive in 2018. LST had risen by around 5.5 degrees C from 1990 to 2018. The lower temperature zones prevailed in the water bodies, forests and agricultural lands whereas higher temperature zones were visible in the river sand bars and highly urbanized areas. The method used in this study is very successful in sparse built-up areas. The outputs of the study will be a great input in the city masterplan for landscape optimization and urban ecological balance in the study area and provide baseline information for future researches looking for inspecting the impacts of LULC change on a regional scale in plainland regions.

Automated summary

The study in northwestern Bangladesh revealed a decrease in water bodies, forests, and bare land over the past 28 years, while agricultural land and settlement areas have expanded. The heat island has been spreading, with a rise in land surface temperature, higher temperatures seen in urbanized areas.