Landscape patterns and processes are undergoing gradual changes due to urbanization resulting in the decrease of blue-green space (Estoque et al., 2017; Shiflett et al., 2017; Yu et al., 2019) along with the alteration of atmospheric composition in the near-surface layers (Lewis and Maslin, 2015; Oke, et al., 2017). Urban Heat Island (UHI) one of the most typical urban meteorological phenomena is defined as high-temperature urban areas than surrounding rural areas (Manoli et al., 2019; Oke, et al., 2017), UHI is the difference between the highest urban temperature and countryside of a region (Oke, 1973). Stewart (2011), states that the conventional definition of UHI is facing serious challenges and hence, a new schema of Local Climatic Zone (LCZ) to access UHI pattern and intensity was proposed by Stewart and Oke (2012). The urbanization process results in the replacement of natural surface by artificial impervious surface which leads to UHI effects (Lo, et al., 1997). Urban energy consumption, air pollution, water shortage, and extreme hot waves are largely related to UHI effects worldwide (Coseo and Larsen, 2014; Debbage and Shepherd, 2015; Zhang et al., 2013). Du et al., (2019) state that the importance of urban planning and landscape ecology, and mitigation of UHI effects are the major focuses of the recent studies. Undergoing patches of high landscape fragmentation, urbanization leads to climatic change at both local and global levels including the alternation of biogeochemical cycle (Grimm et al., 2008; Yao et al., 2019). Studies have highlighted that UHI effects are strengthened by both urban size and population (Zhang et al., 2015; Ramamurthy and Bou-Zeid, 2017; Wu et al., 2019; Dai et al., 2021).
The Urban landscape research refers to water bodies, farmlands, urban parks, forests, grasslands, and other green spaces as ecological land that have significant cooling effects (Pickett et al., 2011; Gunawardena et al., 2017; Fan et al., 2019), this can be defined as urban blue-green space. Studies suggest that blue and green spaces have Urban Cool Island (UCI) effects (Sun et al., 2012; Anjos and Lopes, 2017; Pelorosso et al., 2017). Gunawardena et al.,(2017) highlight that blue-green space has high thermal capacity and evaporation effects which mitigates UHI effects by cooling down the surrounding microclimate. But to infinitely increase the blue-green area in cities is impracticable due to land use efficiency. The urban researcher states that maximizing the UCI effect with limited space is the most practical alternative (Zhang et al., 2017; Montazeri et al., 2017; Dai et al., 2018).
Urban blue-green space as a prominent component of the ecosystem, provides large numbers of ecosystem services such as regulating micro-climate, carbon and oxygen fixing, biodiversity conservation, and many others (Tzoulas et al., 2007), it can also mitigate the deterioration of urban environment caused by urbanization (Dang and Li, 2021). Peng et al. (2016) highlight that the UHI effect would be significantly mitigated if the ecological land coverage exceeds more than 70% in urban areas. Studies have found that the cooling effect of blue-green space depends on the shape, size, connectivity, and complexity of the space.
The greenness of the vegetation and blueness of the water bodies is measured by Normalized Difference Vegetation Index (NDVI) (Gunawardena et al., 2017; Kuang et al., 2015; Ren et al., 2016; Santamouris et al., 2018) and Normalized Difference Wetted Index (NDWI) respectively. However, some researchers have proposed that rather than landscape composition, landscape configuration is a prominent factor in the cooling effect of blue-green space (Peng et al., 2016; Sun and Chen, 2017; Yu et al., 2018).
The understanding of the land surface-atmosphere exchange process at both local and global levels can be improved with new perspicacity into LST which would provide a valuable surface state metric for numerous applications (Li et al., 2023). Hollmann et al., (2013) state that the United States (US) Climate Change Science Program, National Aeronautics and Space Administration, as one of the 10 essential climate variables in the land biosphere designated by the Global Climate Observing System, LST has been recognized as an essential Earth surface parameter. LST is an important parameter to measure the urban health status (Chaudhuri and Mishra 2016) as it provides information regarding climate which aids in understanding and anatomizing urban climate (Bendib et al. 2017; Govind and Ramesh 2019). The correlation between LST and urban expansion has been examined by numerous studies (Ali et al. 2017; Nandkeolyar and Kiran 2018; Sahana et al. 2019; Mukherjee and Singh, 2020).
The casual relationship between UHI and urbanization led many researchers to study the mechanism of the urban landscape and its thermal environment (Liu et al., 2018; Silva et al., 2018). Land surface temperature (LST) derived from remotely sensed imagery is generally used to study the spatio-temporal pattern of LST and its relation with urban landscapes with multi-scale modeling (Estoque et al., 2017; Qiao et al., 2019). Recent studies highly emphasize the role of Urban Green Space (UGS) (Gago et al., 2013; Wu and Ren, 2019; Yao et al., 2020) and Urban Blue Space (UBS) in the urban planning process.
Land use and land cover (LULC) change is another prominent parameter used to study urbanization and its impacts (Mukherjee and Singh, 2020). The alteration of LULC is fueled by the conversion of the landscape by anthropogenic activities (Xiao and Weng 2007; Tan et al. 2010). Previous studies highlight that the impact of LULC changes can also be examined with the aid of LST (Feizizadeh et al. 2013; Adams and Smith 2014; Sahana et al. 2016; Tran et al. 2017). The relationship between LST and LULC can be examined by the Normalized Difference Vegetation Index (NDVI) (Nandkeolyar and Kiran 2019; Guha et al. 2018).
As India is going through a massive urbanization process, today one in every three Indians dwells in an urban area (Mukherjee and Singh, 2020), India has about 475 urban agglomerations (UA) or cities (Census, 2011). The rapid pace of urban expansion in India is not only limited to the mega cities but also has impacted other urban agglomerations throughout the country. Studies reveal that urban blue-green studies in India mainly focus on megacities, even in which only green space has the primary focus.