Urban Expansion and Rising Surface Temperature: A Multi Temporal Assessment in Kochi Metropolis, Kerala

2021 ◽  
Vol 14 (12) ◽  
pp. 48-54
Author(s):  
Lekshmi P.T. Arya ◽  
T.S. Lancelet

The process of urbanization and urban growth has resulted in rapid, uncontrolled conversion of natural land cover and spreading of impervious concrete surfaces in many parts of the world leading to serious environmental concerns. There are a myriad of micro climatic effects due to urban growth. One of the significant consequences is the rising urban temperature. Urban surface temperature responds to changes in land use/land cover dynamics and urban expansion. This would ultimately lead to local climatic changes and would accentuate global warming. Geo spatial technology provides sophisticated tools for analyzing urban features and micro climates. Land surface temperature (LST) or the radiant energy from earth surface can be calculated using thermal bands of satellite data. Kochi, the largest urban agglomeration in Kerala, is undergoing hasty developments and land modifications. This study attempts to monitor changes in land surface temperature from 2000 to 2020 along with changes in built up and vegetation cover. The results revealed that the average surface temperature of Kochi recorded an increase of 0.60C and the loss of green cover has contributed to the increased temperature. Moreover, the LST exhibits a strong positive correlation with built up land expansion. The study findings stand helpful for urban planning and sustainable development of the city.

2021 ◽  
Vol 283 ◽  
pp. 01038
Author(s):  
Jing Sun ◽  
Jing He

The rapid urbanization process has recently led to significant land use and land cover (LULC) changes, thereby affecting the climate and the environment. The purpose of this study is to analyze the LULC changes in Hefei City, Anhui Province, and their relationship with land surface temperature (LST). To achieve this goal, multitemporal Landsat data were used to monitor the LULC and LST between 2005 and 2015. The study also used correlation analysis to analyze the relationship between LST, LULC, and other spectral indices (NDVI, NDBI, and NDWI). The results show that the built-up land has expanded significantly, transforming from 488.26 km2 in 2005 to 575.64 km2 in 2015. It further shows that the mean LST in Hefei city has increased from 284.0 K in 2005 to 285.86 K in 2015. The results also indicate that there is a positive correlation between LST and NDVI and NDBI, while there is a negative correlation between LST and NDWI. This means that urban expansion and reduced water bodies will lead to an increase in LST.


Land ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1106
Author(s):  
Auwalu Faisal Koko ◽  
Yue Wu ◽  
Ghali Abdullahi Abubakar ◽  
Akram Ahmed Noman Alabsi ◽  
Roknisadeh Hamed ◽  
...  

Rapid urban expansion and the alteration of global land use/land cover (LULC) patterns have contributed substantially to the modification of urban climate, due to variations in Land Surface Temperature (LST). In this study, the LULC change dynamics of Kano metropolis, Nigeria, were analysed over the last three decades, i.e., 1990–2020, using multispectral satellite data to understand the impact of urbanization on LST in the study area. The Maximum Likelihood classification method and the Mono-window algorithm were utilised in classifying land uses and retrieving LST data. Spectral indices comprising the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Built-up Index (NDBI) were also computed. A linear regression analysis was employed in order to examine the correlation between land surface temperature and the various spectral indices. The results indicate significant LULC changes and urban expansion of 152.55 sq. km from 1991 to 2020. During the study period, the city’s barren land and water bodies declined by approximately 172.58 sq. km and 26.55 sq. km, respectively, while vegetation increased slightly by 46.58 sq. km. Further analysis showed a negative correlation between NDVI and LST with a Pearson determination coefficient (R2) of 0.6145, 0.5644, 0.5402, and 0.5184 in 1991, 2000, 2010, and 2020 respectively. NDBI correlated positively with LST, having an R2 of 0.4132 in 1991, 0.3965 in 2000, 0.3907 in 2010, and 0.3300 in 2020. The findings of this study provide critical climatic data useful to policy- and decision-makers in optimizing land use and mitigating the impact of urban heat through sustainable urban development.


2021 ◽  
Vol 2 (1) ◽  
pp. 14-27
Author(s):  
Ali Khyami

Remote sensing (RS) technology has been used together with geographic information systems (GIS) to determine the LC types, retrieve LST, and analyze their relationships. The term Greater Beirut Area (GBA) is used to refer to the city of Beirut and its suburbs which witnessed rapid urban growth, after the end of the civil war, in the last decade of the twentieth century, due to the increase in the number of its inhabitants, and the prosperity and development of sectors such as; industrial, trade, tourism, and construction. These factors led to a wide change in the land cover (LC) types and increased land surface temperature LST. The results showed an increase in built-up areas by 29.1%, and agricultural lands by 6%, while bare land, forests, and seawater decreased by 28.5%, 4.9%, and 1.9%, respectively. These changes caused large differences in the LST between built-up areas and other LC types. The highest LST recorded was in built-up areas (33.03°C in 1985, and 34.01°C in 2020), followed by bare lands (32.61 °C in 1985 and 33.49°C in 2020), cropland (31.23°C in 1985 and 32.17°C in 2020), forest (30.08°C in 1985 and 30.47°C in 2020), and water (24.97°C in 1985 and 28.15°C in 2020). Consequently, converting different LC types into built-up areas led to increases in LST and changed microclimate.


2019 ◽  
Vol 12 (3) ◽  
pp. 117-140
Author(s):  
Sunil Kumar ◽  
Swagata Ghosh ◽  
Ramesh Singh Hooda ◽  
Sultan Singh

Abstract Land use Land cover have significance in relation to Land, the most vital and fundamental resource pertaining to the urban development. Unprecedented urban growth has a noteworthy impact on natural landscape by converting natural land-cover in Haryana. Hisar, an area recognized for rapid urban growth is less explored in terms of research. The present research has shown a significant change in land use in terms of expansion of built-up area from 3.7 % (1991) to 5.0 % (2001) and 6.2 % (2011) by encroaching into agricultural land. Despite the clear difference between average land surface temperature for built up and non-built up area, grazing land and sandy waste, bare land in the rural surrounding possess higher temperature compared to the city core which contradicts the reported impact of urbanization earlier. Such contrary pertains to sparse vegetation cover leading to reduced evaporative cooling during dry pre-monsoon summer in the rural surrounding. On the other side, green parks and plantation in the city contribute to lower mean temperature because of high rates of evapotranspiration and produce ‘oasis effect’ in the present study area located in semi-arid climatic zone. Regression analysis between temperature and Normalized Difference Vegetation Index, Normalized Difference Built-up Index exhibited a strong negative and positive correlation respectively (Pearson’s r: between -0.79 to -0.87 and between 0.79 to 0.84 respectively). Future land use prediction project an increase (1.3 %) in built-up area from 2011 to 2021. This study recommends urban plantation and prohibition to overgrazing to check the heat effect.


2020 ◽  
Vol 12 (5) ◽  
pp. 801
Author(s):  
Haibo Yang ◽  
Chaofan Xi ◽  
Xincan Zhao ◽  
Penglei Mao ◽  
Zongmin Wang ◽  
...  

Satellite-based remote sensing technologies are utilized extensively to investigate urban thermal environment under rapid urban expansion. Current Moderate Resolution Imaging Spectroradiometer (MODIS) data are, however, unable to adequately represent the spatially detailed information because of its relatively coarser spatial resolution, while Landsat data cannot explore the temporally continued analysis due to the lower temporal resolution. Combining MODIS and Landsat data, “Landsat-like” data were generated by using the Flexible Spatiotemporal Data Fusion method (FSDAF) to measure land surface temperature (LST) variations, and Landsat-like data including Normalized Difference Vegetation Index (NDVI) and Normalized Difference Built Index (NDBI) were generated to analyze LST dynamic driving forces. Results show that (1) the estimated “Landsat-like” data are capable of measuring the LST variations; (2) with the urban expansion from 2013 to 2016, LST increases ranging from 1.80 °C to 3.92 °C were detected in areas where the impervious surface area (ISA) increased, while LST decreases ranging from −3.52 °C to −0.70 °C were detected in areas where ISA decreased; (3) LST has a significant negative correlation with the NDVI and a strong positive correlation with NDBI in summer. Our findings can provide information useful for mitigating undesirable thermal conditions and for long-term urban thermal environmental management.


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