Conclusion

Kolkata is the 13th most populated and eighth largest urban agglomeration in the world, having a population of approximately 14.11 million. Population density has increased from 2039 persons per sq.km (in 1971) to 3879 (in 2011) persons per sq.km. Urban structure refers to the heterogeneous alignment of terrestrial objects and characteristics of land uses (such as built-up, vegetation, water bodies and open spaces) in a region. Rapid urbanisation involving large scale land transitions necessitates the understanding of urban dynamics (spatial extent, up-to-date data, etc.). The current endevour demonstrates the quantification of urbanisation with its spatiotemporal aspect, pattern and structure through temporal remote sensing data along with density gradients and spatial metrics. Urbanization analysis using temporal remote sensing data for Kolkata reveals that area under vegetation has declined from 36% (1980) to 13% in 2010. Land use analysis reveals a decline of vegetation from 33.6 % (1980) to 7.36% (2010). During 2010, built-up constitute 8.6%, water bodies 3.15% and other categories about 80.87%. Increasing Shannon’s entropy values highlight the tendency of sprawl that demands for appropriate policy interventions to provide basic amenities in the regions. Temporal remote sensing data with Shannon entropy have provided substantial multi-purpose information at both regional and local levels for describing, understanding and monitoring the spatial configuration of urban growth to support decision making in complex urban systems.

Spatial metrics computed in density gradients helped in elucidating spatio-temporal patterns of urbanisation at local levels and support sustainable urban planning and management decisions. Metrics PLAND show an increase in urban pixels. Contagion metrics (such as number of patches, patch density, edge density, IJI, AWMSI) highlight urban sprawl at outskirts and in the buffer regions, while aggregation indices (Clumpiness, aggregation, NLSI) highlight the process of aggregation at the city centre. The urban pattern analysis through spatial metrics provided insights about the spatial patterns temporally and quantitatively. The metrics highlighted the anthropogenic pressures on the landscape. This indicates that the landscape at the outskirts is highly fragmented and city administration need to plan in a phased manner to provide basic amenities.  Proper land use planning with temporal monitoring would aid in sustainable planning. Coexistence of economic activities, ecological integrity, infrastructural deficits, poverty alleviation, and population growth are posing serious challenges to urban planning. These require integrated interdisciplinary studies to understand the multi-dimensional and complex interactions of urban systems to analyse effects of different measures.