Figure 3 Methodological flowchart adopted for the study
Related Figures (19)
Fig. 1 Location map of the study area showing West Bengal with Purulia district (a), LULC map of Purulia district (b) and Purulia municipality (c) coverage, agricultural land, water body, etc., and land cover change analysis helps to understand the changes of the natural surface into residential and commercial areas over the study area at different time periods (Ra- machandra et al. 2013; Bharath et al. 2017). The genera impact of urbanisation on the pattern of land uses is increasing the rate of man-made land or built-up area and decreasing the rate of natural land like vegetation cov- erage, bare land and water body. The LULC classifica- tion was performed here to show a visualisation of the pattern of LULC changes and urban spatial expansions for the year of 1998, 2008 and 2018. The supervised classification with maximum likelihood algorithm method was applied here to measure land use changes over time, and this method has been proved to be an efficient among another classifier (Bharath et al. 2017). The images were classified into five classes, namely agricul- tural land, bare land, built-up area, vegetation coverage and water body. Then, to investigate the spatial pattern of urban areas from 1998 to 2018, the LULC classes were reclassified into built-up and non-built-up areas. In this study, built-up class was used to represent urban expan- sion areas. Table 1 Specified information of utilised Landsat satellite imageries (1998-2018). Source: US Geological Survey Identification of urban centre & generation of dataset for Shannon’s Entropy Calculation Table 2 Accuracy assessment for LULC of Purulia municipality Fig. 4 Land use and land cover map of Purulia municipality in (a) 1998, (b) 2008 and (c) 201 The LULC analysis based on supervised classification technique for the year 1998, 2008 and 2018 shows that the five land use categories of agricultural land, bare land, built-up area, vegetation coverage and water body were changing in a differential rate over the time (Fig. 4). The agricultural land has been decreased by 6.56% during 1998-2008, 4.53% during 2008-2018 and 10.79% during 1998-2018 (Table 3). It is seen that agricultural land, vegetation coverage, bare land and water body have been decreased (Fig. 5) due to quick land use transformations for shifting of primary economic activities to secondary and tertiary, demand for residential, recreational land. This demanding situation happens due to ever-increasing pop- ulation and modernisation which always try to increase manmade land over natural land. These results are very much similar to the works of Liao and Wei (2014), Mosammam et al. (2016), Alam et al. (2019), Meer and Mishra (2020), etc. As agriculture is the main occupation of the people in this district (District Census Handbook 2011), the rate of agricultural land degradation is Among other land use types, the built-up area is changing in a positive and consistence way and it was of the people in this district (District Census Handbook Table 3 The distribution of area of different land use types in Purulia municipality in 1998, 2008 and 2018 which is a considerable parameter to maintain the quality of urban environment (Kuchay and Bhat 2014; Garouni et al. 2017). Fig. 6 Changing pattern of area of different LULC types in Purulia municipality increased by 122% within the 20 years due to increasing demand of land for economic and as well as residential purposes, and the study is related to Punia and Singh (2012), Alam et al. (2019). The interesting fact is that the rate of growth in the built-up areas has decreased from 91.92% (1998-2008) to 15.67% (2008-2018) due to compact growth of urbanisation in the recent phase (Table 3 and Fig. 6). The facts on land use assessment disclose the undesirable changes in land use pattern which is going to be a matter of concern for the Purulia munici- pality. For example, due to built-up expansion this urban body lacks natural space like vegetation coverage (Table 3) body lacks natural space like vegetation coverage (Table 3) As land use change is a dynamic phenomenon, the main issues are to quantify and find out the source of the land use change and the reasons behind it (Knox 1993; Alsharif and Pradhan 2014). In Fig. 7 it is observed that 15.33% water bodies have been replaced by the built-up area during first Fig. 7 Percentage of changing land use from one land use type to others during 1998-2008, 2008-2018 and 1998-2018. a Water body changed into different land uses, b Bare land changed into different land uses, ¢ Agricultural land changed into different land uses, d Vegetation coverage changed into different land uses Table 4 The built-up area in different quadrants from 1998 to 2018 Deshbandhu Road which is 1.22 km away from CBD but the vacant lands in the outside part of municipality have been converted to agricultural land and random residential units. So, it must be stated that built-up area has a tendency to encroach the other land use types based on accessibility factor because there has more chance to conversion of land to built-up area which exist in closer to its (Liao and Wei 2014). From this section of study, it is justified that the increasing built-up density is one of the crucial factors for land use changes in the urban body (Dutta and Das 2019). So, overall scenario depicts that the perception and con- sciousness of human about their livelihood which is the main determining factor for LULC change in the study region. Table 6 Distribution of built-up density from the CBD to the periphery parts of the district too, to access the health facilities people comes from a distance in this municipality (Fig. 10). Due to better communication facilities, continuous interaction can be notified with the other urban centres as well as surrounding rural centres. Hence, it can be explained that Shannon’s entropy is a very useful method to identify the nature of urban sprawl because it not only affects the physical environment but also determine the socio-eco- nomic structure of an urban body. In the study, Sun et al. 2007 suggested that ‘Smart growth’ policy could prevent the urban sprawl phenomenon. However, it should be clear that Purulia administrative body didn’t take any such kind of policies for the municipality to maintain the built-up growth. Fig. 8 Quadrant-wise division for Shannon’s entropy calculation in 1998 (a), 2008 (b) and 2018 (c) Fig. 9 Division of buffer zones for measuring built-up density of 1998 (a), 2008 (b) and 2018 (c) types, vegetation coverage, bare land, agricultural land and water bodies have been degraded due to rapid growth of built-up areas by the encouragement of urbanisation. On the other hand, the rate of spatial expansion of built-up areas has been slowed down from 1998-2008 to 2008-2018 due to compact growth in the following decade. In the five quadrants, namely N, NE, E, SE and S, the entropy values are high and rest three quadrants are experiencing the low entropy value. Lastly, the density of built-u p area has been decreased from CBD to periphery in a consistent way; based on this finding, it is clear that here a healthy and sustainable built-up development should be needed related where people can get equal availability of urban- opportunities from CBD to periphery. From this outcome, it can be said that this municipality belongs to the take-off stage of urban development. Fig. 10 Locational distribution of basic amenities across the buffer zones
