Monitoring Spatiotemporal Land Use and Land Cover Dynamics: A Case Study of Kolkata Megapolis, India (1991–2021)

The rapid growth of population, demographic shift in the form of rural–urban migration and high pace of urban transition in India have posed unprecedented challenges to city planners. Kolkata Megapolis, the capital of West Bengal State, is observing drastic changes in LULC (Land Use and Land Cover) due to high growth in population and consequential adverse effects requiring mapping and monitoring of LULC over a long period to assess the change occurring therein. Therefore, in the present work, Supervised classification with Maximum Likelihood Classifier (MLC) is performed on remote sensing images of Landsat-5 TM (Thematic Mapper) of 1991 and Landsat-8 OLI/TIRS (Operational Land Imager/Thermal Infrared Sensor) of 2021 to produce multi-temporal LULC maps which are used for studying the long-term periodical change and to carry out the transition matrix analysis. The overall classification accuracy of over 85% proves that the classified maps are accurate and can be used for further reliable analysis. The results show a maximum increase in built up by 594.79 km2 (32.87%) while agriculture experienced the highest decline by 429.13 km2 (23.71%) over a period of 30 years during 1991–2021. The forest also reduced by 139.13 km2 (7.69%) along with loss of water bodies. The change matrix analysis (1991–2021) results found that nearly all transformation is due to built up, primarily from agriculture by 401.79 km2 (22.20%), forest by 179.74 km2 (9.93%) and water body by 41.65 km2 (2.30%). The huge impervious development in form of built up is reflecting in degradation of land, environment and quality of life. This work is expected to benefit urban planners and decision-makers in the formation of effective plans and policies for sustainable development of the Kolkata megapolis.