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The studies of urban heat islands or urban thermal environments have attracted extensive attention, although there is still a lack of research focused on the analysis of long-term urban thermal environment change with fine spatial resolution and actual exposure of urban residents. Taking the rapidly urbanizing city of Nanjing, China as an example, this study utilizes the Landsat-derived daytime time-series land surface temperature data to comprehensively assess the city's long-term (30-year) urban thermal environment change. The results showed that: (1) The overall surface urban heat island intensity showed a noticeable trend of first increasing and then decreasing from 1990 to 2020. (2) It exhibited the detailed spatial distribution of urban heat/cold islands within the urban center boundary. The percentage of surface urban heat islands was 77.01% in 1990, and it increased to 85.79% in 2010 and then decreased to 80.53% in 2020. (3) More than 65% of the urban residents have lived in areas with a surface urban heat island intensity greater than 3.0 °C, which also showed a trend of first increasing and then decreasing from 1990 to 2020. The methods and findings of this study can provide a reference for other studies on urban thermal environment changes and urban sustainable development. [ABSTRACT FROM AUTHOR]

Land use and land cover (LULC) changes resulting from rapid urbanization are the foremost causes of increases in land surface temperature (LST) in urban areas. Exploring the impact of LULC changes on the spatiotemporal patterns of LST under future climate change scenarios is critical for sustainable urban development. This study aimed to project the LST of Nanjing for 2025 and 2030 under different climate change scenarios using simulated LULC and land coverage indicators. Thermal infrared data from Landsat images were used to derive spatiotemporal patterns of LST in Nanjing from 1990 to 2020. The patch-generating land use simulation (PLUS) model was applied to simulate the LULC of Nanjing for 2025 and 2030 using historical LULC data and spatial driving factors. We simulated the corresponding land coverage indicators using simulated LULC data. We then generated LSTs for 2025 and 2030 under different climate change scenarios by applying regression relationships between LST and land coverage indicators. The results show that the LST of Nanjing has been increasing since 1990, with the mean LST increased from 23.44 °C in 1990 to 25.40 °C in 2020, and the mean LST estimated to reach 26.73 °C in 2030 (SSP585 scenario, integrated scenario of SSP5 and RCP5.8). There were significant differences in the LST under different climate scenarios, with increases in LST gradually decreasing under the SSP126 scenario (integrated scenario of SSP1 and RCP2.6). LST growth was similar to the historical trend under the SSP245 scenario (integrated scenario of SSP2 and RCP4.5), and an extreme increase in LST was observed under the SSP585 scenario. Our results suggest that the increase in impervious surface area is the main reason for the LST increase and urban heat island (UHI) effect. Overall, we proposed a method to project future LST considering land use change effects and provide reasonable LST scenarios for Nanjing, which may be useful for mitigating the UHI effect. [ABSTRACT FROM AUTHOR]

Urban road DEM is not only an important basic geographic information data of the city, but also an important element to describe and express the urban topography, and it is an indispensable part of the construction of the smart digital city, urban planning and urban surface process simulation. Previous methods for constructing urban road DEMs do not sufficiently consider the actual morphological characteristics of urban roads, and morphological distortion is evident in the expression of urban roads, seriously affecting the application of urban rainfall flood simulation and urban pipe network design. In response to these problems, this study proposed a considering morphological characteristics fine (CMCF) method of urban road DEM construction, selected a typical urban road area in the Jianye District of Nanjing City in China as the study area, used the 1:500 digital line graphic as data source, hierarchized roads in accordance with different morphological characteristics from the perspective of DEM construction, constructed the corresponding DEMs, and finally merged all levels of road DEMs to produce a complete high-precision urban road DEM. Results showed that the DEM constructed using the CMCF method not only exhibited higher elevation accuracy than the urban road DEM constructed using previous methods, i.e., inverse distance weighting (IDW) and triangulated irregular network (TIN) methods, with a mean error and a root-mean-square error of 0.015 and 0.060, respectively, but it can also accurately express the spatial element composition form and road morphological characteristics of urban roads, avoiding the distorted expression of road morphological characteristics. This study can provide a reference for a new DEM construction method and data support for smart digital city construction and urban surface simulation. [ABSTRACT FROM AUTHOR]

Ecological corridors are crucial for preserving biodiversity in human-impacted areas, but previous work has focused on landscape connectivity rather than ensuring that connected areas are suitable for migrating species. Our study developed a framework integrating landscape similarity assessment to prioritize corridor protection and construction. Taking Nanjing Metropolitan Area in 2020 as a case, we identified ecological sources from the perspectives of function and structure. The minimum cumulative resistance (MCR) model and gravity index were then employed to detect ecological corridors and assess connectivity. The similarity index was subsequently applied to assess the landscape similarity between ecological sources, which was quantified from three aspects of composition, as well as configuration and physical geography. Final classification and prioritization of corridors for protection and construction were based on the precedence matrix method. Our results showed that 58 ecological sources were potentially connected by 103 corridors. The 39 corridors combining high connectivity and high similarity were assigned the highest priority for protection, and the 27 corridors with low connectivity but high similarity were assigned to the category with high construction priority. Our findings advance theoretical and practical understanding of ecological corridors by demonstrating that high priority corridors can be identified for focused conservation efforts. • A novel framework that integrates similarity assessment to assign ecological corridor priority was provided. • Landscape similarity were assessed in 3 aspects: composition, configuration, and physical geography. • Differential protection and construction strategies for ecological corridors were formulated usingusing our framework. [ABSTRACT FROM AUTHOR]

• An integrated framework for ecological protection and restoration is proposed. • Recreational service is estimated by considering spatial accessibility. • Priority areas of protection are identified based on trade-off of ecosystem service. • Ecological protection and restoration pattern is identified at the two scales. • Land management measures are proposed for ecological protection and restoration. Ecological protection and restoration is an important bridge to adjust the contradiction between ecological protection and economic development, and it is essential for ecological security and sustainable development. An integrated evaluation framework for multiscale ecological protection and restoration based on multi-scenario trade-offs of ecosystem services was proposed in this study, and the city of Nanjing was taken as an example to identify key areas and land strategies for ecological protection and restoration. In our framework, carbon storage, habitat quality, nitrogen retention, and water conservation services were quantified by InVEST model, and recreational service was quantified as the total areas of green spaces within ecological land accessibility. The ordered weighted averaging model was used to simulate the priority areas of ecological protection under 11 scenarios of trade-offs of ecosystem services, and ecological sources, ecological corridors, ecological pinch points and ecological barriers at the Nanjing city scale and the main urban scale were identified based on circuit theory. We also nested the ecological conservation and restoration patterns at two scales and analyzed the coincidence degree between two scales. Our results showed that the S7 scenario had the highest average conservation efficiency among the 11 scenarios. The priority areas for ecological protection in this scenario had an area of 1582 km2 and are mainly distributed in the central and southern parts of Nanjing. In our study, 50 ecological sources (with an area of 1153.36 km2), 77 ecological corridors (with a length of 443.04 km), 25 key nodes for ecological protection and 31 key nodes for ecological restoration were identified in Nanjing. By nesting the ecological protection and restoration patterns of two scales, we found that the overlap of ecological sources and ecological pinch points at two scales is 100%, and the overlap of ecological corridors and ecological barriers is 45.28% and 57.14%, respectively, which means that the ecological protection and restoration patterns at the two scales in Nanjing were well connected, but the ecological network at the large scale cannot fully reflect the real ecological problems and needs at the small scale. We suggest regarding the ecological protection and restoration pattern at large scale as the basis and the pattern at small scale as the supplement. We also propose that priority should be given to the protection and restoration of key areas where the two scales overlap, and strictly control their land development to promote sustainable development. This framework and these strategies are applicable to other rapidly urbanizing regions of the world. [ABSTRACT FROM AUTHOR]