4.1. Urban Expansion Analysis
Over the last two decades, the city of Jaipur has undergone spatial and structural transformations. The absolute territory of the built-up area was 97.55 square kilometres in 2000, 140.48 square kilometres in 2008, and 149.69 square kilometres in 2016. In comparison to the city zone of 2000, we can see that the south-east, north-west, and west sides of the city are growing. Water bodies and green space have changed as the city has slowly expanded towards the north-west and south-east boundaries.
For all three timeframes examined, it is discovered that there is an expanding pattern in the urban region from 2000 (97.55 Sq.km), 2008 (140.48 Sq.km), and 2016 (149.69 Sq.km), implying that the territory of green space initially decreased from 11.93% in 2000 to 4.98% in 2008 and then marginally increased to 6.78% in 2016.
It was discovered that 25.08% of development in the developed territory of urban land occurred throughout a 16-year period from 2000 to 2016. In the first eight years (from 2000 to 2008), urban development was 20.63%, with an average annual development rate of 5.36 square kilometres. Over an 8-year period (2008–2016), urban development was 4.45%, with an average annual development rate of 1.15 square kilometres. As a result, while comparing the years 2000 to 2008 to the years 2008 to 2016, the Jaipur city expansion rate has increased significantly.
4.2. Sprawl Pattern Analysis
Rambling has also taken hold of Jaipur city. A careful investigation of these spreads reveals information about the development components of these emergent urban agglomerations. In terms of sprawl direction, satellite data show that the city is expanding to the west, north-west, and south-east independently. The primary cause for such expansion could be the availability of land at a significantly lower cost in those zones, an excellent vehicular communication system, access to high institutional and infrastructural amenities, proximity to the main city, and so on. Another important factor could be the shift from rural to urban areas. The area related to the primary urban zone, on the other hand, exhibits the characteristics of a radial sprawl pattern, followed by a comparative event in the north section of the research area. While there are some scattered new developments in various regions of the city's south and east (Figure: 4).
Characteristics of the Spatiotemporal urban expansion process
Jaipur's built-up area has grown significantly, largely radiating away from the city center. Along with the expansion of the main urban zone, little encompassing built up have gradually expanded, eventually converging with the main urban territory. Urban land expanded by over half, from 97.55 km2 in 2000 to 149.69 km2 in 2016, with an average expansion rate of 1.5%. During the period 2000–2008, the estimated urban expansion area, rate, and intensity were 42.93 Sq. km, 5.50%, and 2.59%, respectively, as shown in Table 1. The urban compactness ratio increased from 0.16 in 2000 to 0.20 in 2008 and then increased by 0.01 from 2008 to 2016, totaling 0.21 (Table 1). From 2000 to 2016, the urban compactness ratio increased by 0.06. As a result, the spatial growth of built-up in Jaipur city shifted swiftly outward surrounding the center of town from 2000 to 2008, and then gradually changed into a more moderate development through infilling from 2008 to 2016.
In a variety of ways, Jaipur's urban growth revealed significant spatial variability. The most rapid urban growth occurred in the north-west, south-east, and west directions. Development rates in the east and upper east, on the other hand, were negligible. Furthermore, the urban expansion rates and intensities in different directions for different durations showed significant contrasts. The rate of urban expansion was highest in the western direction between 2000 and 2008, then in the south bearing between 2000 and 2008, and in the north bearing between 2008 and 2016. From 2008 to 2016, the rate of urban expansion to the city core was the slowest. However, although continually being greater in the northwest and north headings, the urban compactness ratio did not show any discernible variations. The ratio, in particular, demonstrated a very distinct change in the northern path, expanding by 0.06 between 2000 and 2008.
Table 1: Table showing Rs, Is and BCI in 2000, 2008 and 2016
Parameter | 2000 | 2008 | 2016 |
Area | 97.55 sq. km | 140.48 sq. km | 149.69 sq. km |
Rs | | 5.50 | 0.81 |
Is | | 2.59 | 0.55 |
BCI | 0.16 | 0.20 | 0.21 |
4.3. Spatiotemporal analysis of LST
The maps (Figs. 5–18) depict the geographical and temporal circulation of the month-to-month, seasonal, and yearly LST of Jaipur based on MODIS MOD11A2 V6 LST retrievals. The LST of Jaipur city has lesser esteems in many locations, and they are one-sided in many zones in the inquiry area; with a special case in the late spring seasons, when LST retrievals are highest in the city's center.
LST of Jaipur city from March to May (2000, 2008, and 2016) is highly irregular in month monthly distribution. In the year 2000, May was the warmest month, with temperatures reaching 48.95 degrees Celsius during the day and 29.44 degrees Celsius at night. During the summer season (2000), the most extreme LST of Jaipur city is 45.57 C during the day and 39.79 C at night, while the highest LST is 27.67 C and the lowest is 21.44 C. In 2008, April was the hottest month, with temperatures reaching 46.05 degrees Celsius during the day and 27.66 degrees Celsius at night. During the summer season (2008), the maximum LST in Jaipur city is 40.89 C and the lowest is 36.45 C during the day, while at night, the highest LST is 25.29 C and the lowest is 19.29 C. In 2016, the LST in Jaipur city increased significantly, reaching 50.77 C during the day and 31.33 C at night in May. During the summer season (2016), the highest LST in Jaipur is 50.77 C and the lowest is 43.72 C during the day, while the most extreme LST in Jaipur is 31.33 C and the lowest is 26.67 C at night.
In this study, efforts were also undertaken to analyze MODIS inferred Land Surface Temperature (LST) data from the years 2000, 2008, and 2016. The maximum LST in Jaipur city in 2000 was 29.07 C and the lowest was 24.5 C during the day, while the maximum LST at night was 18.19 C and the lowest was 11.50 C. During the day, the yearly highest LST was 34.33 C and the lowest was 26.91 C in 2008, while at night, the highest LST was 21.32 C and the lowest was 11.58 C. Similarly, the most notable LST for Jaipur city in 2016 was 35.51 C and the lowest was 27.27 C during the day, while the most notable LST was 22.61 C and the least LST was 18.11 C at night. An examination of the years 2000, 2008, and 2016 reveals that 2016 is the warmest year and 2000 is the least hot.
The UHI's impact zone expanded inexorably from 2000 to 2016, primarily in the city center. High-temperature areas were predominantly dispersed in the focal urban region and neighboring built-up areas from 2000 to 2008. After 2008, the high-temperature zone expanded beyond the core urban zone. The high-temperature regions comprised 103.86 Sq. km in 2016, accounting for 49.75% of the total land area, which was 35.24 km2 larger than in 2000, expanding by 16.61%. This demonstrates that, despite an increase in the UHI's zone of influence between 2000 and 2016.
4.4. Urban Form impact on Urban Heat Island
In this research, we looked at urban land expansion and LSTs during three time periods. The results showed that the two indicators (Rs and Is) were highly connected, indicating that the event of UHI impact is attributed to the rapid transition from rural to urban area. Large territory structures intrude on progressively green land, as the expansion of impermeable surface lessens warm idleness and the vegetation record compels dissipation, lowering the loss of warmth via latent heat flux and boosting UHI impact. Because of the similar metropolitan scale and compressed urban structure, the UHI became progressively extreme. The urban grounds in Jaipur's upper east and west sides have grown unevenly. Although the compactness ratio is clearly higher in the center zone, the urban heat island proportion index is high, indicating a more grounded UHI impact in the central region than in the other regions of Jaipur city. Clearly, excessive urban density and impermeable surface would impair urban-rural air circulation, preventing urban inward warmth propagation and therefore increasing temperature differences between the urban and rural zones. Because the LSTs in Jaipur city were generally classified as high or low, the high temperature category was used in the investigation. The encroachment of urban land on rural land, as well as a variety of human activities (for example, population density, greater travel frequency, and modern construction), at the time resulted in significant changes in thermal radiation, heat storage, and heat transmission channels. As a result, urbanization was the most immediate and significant main thrust of UHI expansion.