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      where T_s = land surface temperature (°C), BT = brightness temperature (K), λ = wavelength of the emitted radiance, ρ = (h * c/σ) = 1.438 *10⁻²mK, and ε = land surface emissivity

1.4 Results and Discussion

      The results of the data analyzed for this study are discussed in four sections.

1.4.1 Pattern of LULC in Barasat

The temporal images of study area were classified in six classes with the help of Maximum Likelihood algorithm. The classification scheme of Land Use/Land Cover (LULC) includes the classes (1) built-up area, (2) built-up with green space, (3) agricultural fallow, (4) bare land, (5) green space, and (6) water bodies (Figure 1.3). A drastic change is observed in the ratio of built-up area and built-up area with green vegetation in the center of the city. Moreover, the aggregation and expansion in built-up area changes rapidly after 2011.

The total area of the Barasat municipality is about 34.5 km² as obtained by the digitized vector layer. The observed change in built-up area is ranging from 6.79% in 2001 to 29.23% in 2017, and simultaneously, there is highest decrease observed in green space ranging from 27.99% in 2001 to 11.50% in 2017 (Table 1.2). Built-up area with green space is increasing, although at a slower rate than the pure built-up area, which implies that the municipality or concerned agency for greenery in urban space is not giving serious thought to the importance of green space in urbanization. There is decrease in surface area of water body and reduction in number of water body within the study area, which may lead to water crisis in near future.

Figure 1.3 Land Use/Land Cover map of Barasat municipality (2001, 2011, and 2017).

Table 1.2 Area statistics of LULC in Barasat municipality.

Class Name	Area in %
2001	2011	2017
Bare land	16.70	13.39	8.25
Water body	2.40	2.36	1.47
Agricultural fallow	7.92	4.75	3.74
Built-up area	6.79	16.38	29.23
Built-up with green space	38.20	40.79	45.80
Green space	27.99	22.33	11.50

      1.4.2 Urban Sprawl

It is imperative from above classified (Figure 1.3) remote sensing images of different time period that the LULC in Barasat municipality area is more inclined toward urbanization. Moreover, the rate of urbanization in the study area has changed rapidly within second decade than the first decennia. It is clear from Figure 1.4 that there are two peculiar patterns of urban growth found in the study area. Initially, the urbanization in the study area shows the linear pattern followed by concentric development in built-up area. The Figure 1.4 clearly shows that in the year 2001, there was only few clusters of built-up area, which is showing trend of linear growth in the year 2011 followed by again concentric development of built-up area in the year 2017. Moreover, due to such sequential developmental pattern in the study area, there is no space for easy air circulation within the urban domain. The scale of growth in urbanization in concentric pattern starting at scale of 1 in the year 2001, it became 2 times in the year 2011 and has increased to 6 times in the year 2017 (Figure 1.5A). However, the scale of growth in urbanization in linear pattern has changed manifold, starting at a scale of 1 in the year 2001, it became 2 times in the year 2011 and in turn it has increased to 4 times in the year 2017 (Figure 1.5B). The impact of concentric urbanization is greater in relation to the linear urbanization pattern during 2011 to 2017 than during 2001 to 2011 (Figure 1.4).

Figure 1.4 Urban Sprawl pattern from 2001 to 2017.

Figure 1.5 (A) The Circular pattern of increasing population from center of the city. (B) The Linear pattern of increasing population alongside road.

      1.4.3 Impact of Urban Sprawl on Vegetation Cover

LULC analysis of temporal imageries clearly shows the impact of urban growth on vegetation cover in the study area. The analyzed remote sensing dataset shows that there is inverse relationship between built-up area and green space. Figure 1.6 shows the amount of changes in green space based on NDVI from 2001 to 2017 through 2011. Moreover, it is also evident from the NDVI images that there is reduction not only in spatial extent of vegetation cover but also there is reduction in overall biomass and chlorophyll as well during the study period. In the year 2001, the NDVI value was ranging from −0.33 to 0.76, while in the year 2011, the lower value is around −0.10 and higher value is around 0.60 and during year 2017 the NDVI is showing lower value of −0.06 and higher value of 0.42. However, there is increase of population density in the central part and radially outward from the city since year 2011 to 2017. Moreover, the temporal NDVI images also shows that there is decrease in vegetation cover as one moves from central part of the city to edges of the study area.

Figure

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