Urban Growth Dynamics and Changing Land-Use Land-Cover of Megacity Kolkata and Its Environs

Spatio-temporal land-use land-cover changes have a long-term impact on urban environments. The present study is based on land-use land-cover changes and urban expansion of megacity Kolkata and its environs over three decades (1991-2018) using multitemporal Landsat data. The study aims to explore and explain the spatio-temporal land-use land-cover change, areal differentiation, spatio-temporal urban growth trajectory and future land-use land-cover prediction with population projection. The spatio-temporal representation found rapid urbanization, i.e. 19% to 57%, exactly three times as in 1991, resulting in significant loss of other than urban/built-up area. Urban trajectory reveals that the expansion mainly occurred in north-east to south-west direction, the zone of both sides of River Hooghly. Areal differentiation map with highest urbanization (3146 ha or UII = 0.64) was identified in the north-north-west part, while least urbanization was identified in the east-north-east direction. On the other hand, this urbanization has grabbed most (i.e. 87%) of the areas within 5-km ring buffer compared to other three ring buffers. Being Kolkata as a traditional city, it has all modern facilities since British rule; as a result, the high population growth and rapid urban expansion were explored in the study. Therefore, urban growth led to radical changes in land-use land-cover, which were witnessed by sharp decreases in sparse vegetation and fallow land. The correlation explained that increasing urbanization has decreased the amount of water body and vegetation. The future prediction graph identified the more horrible picture: the city and its environs will be covered by 67% built-up, while there will be only 3% water body, 14% vegetation and 16% fallow land of the total geographical area with a population (projection) of 28 million in 2051 if it is continued. Such expansion will create a wide range of mismanagement and environmental problems. Hence, the intensive explanation and areal differentiation maps and diagrams prepared using geospatial data will definitely help to understand the urban growth dynamics process and changing form of land-use land-cover and simultaneously decision-making process of the local planners, stakeholders and academicians. Therefore, it also guides to future planning to decrease the adverse effects of urbanization and result in the form of land-use land-cover and makes an eco-friendly megacity as well as sustainable urban development too.