The Impact of Urban Expansion on the Urban Thermal Environment: A Case Study in Nanchang, Jiangxi, China

Abstract

Urban expansion has been changing the urban thermal environment. Understanding the spatial distribution and temporal trends in the urban thermal environment is important in guiding sustainable urbanization. In this study, we focused on the land use/land cover (LULC) changes and urban expansion in Nanchang city, Jiangxi province, China. The four elements in the remote sensing-based ecological index (RSEI) are heat, greenness, dryness, and wetness, which correspond to the land surface temperature (LST), NDVI, NDBSI, and WET, respectively. According to the synthetic images of the average indices, we conducted temporal trend analysis together with statistical significance test for these images. We conducted partial correlation analyses between LST and NDVI, NDVSI, as well as WET. In addition, we used the LULC maps to analyze the multi-year trends in urban expansion. Then, we superimposed the trends in daytime and nighttime LST in summer on urban expansion area to extract the LST trends at sample locations. The results showed that LULC in Nanchang has substantially changed during the study period. The areas with statistically significant trends in LST coincided with the urban expansion areas. Land cover change was the main reason for LST change in Nanchang. In particular, artificial surfaces showed the greatest increase in LST; for per 100 km2 expansion in artificial surfaces, the daytime and nighttime LST increased by 0.8 °C and 0.7 °C, respectively. Among all the study land cover types, water bodies showed the greatest differences in LST change between the daytime and nighttime. There were statistically significant correlations between increases in LST and increases in NDBSI as well as decreases in NDVI and WET. In view of the considerable impact of urban expansion on the urban thermal environment, we urge local authorities to emphasize on urban greening when carrying out urban planning and construction.

Latent Profile Analysis of Mental Health among Chinese University Students: Evidence for the Dual-Factor Model

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Design and Parametric Optimization Study of an Eccentric Parallelogram-Type Uprighting Device for Ratoon Rice Stubbles

“…T straightening the compacted stubbles can contribute to increa season rice. Additionally, the team designed an innovativ claw-type straightening device for ratoon rice aimed at lift achieving a straightening rate of approximately 55% [20,21]. H the machine to re-enter the field during operation, which can In order to address the technical challenge of significant yield reduction in the secondseason rice caused by the high rolling compaction rate during mechanical harvesting of the first-season ratoon rice, Yang et al attempted to enhance the yield and quality of the ratoon season through optimized variety selection and cultivation techniques [13].…”

“…The results demonstrated that straightening the compacted stubbles can contribute to increasing the yield of the second-season rice. Additionally, the team designed an innovative double-layer chain-driven claw-type straightening device for ratoon rice aimed at lifting the compacted stubbles, achieving a straightening rate of approximately 55% [20,21]. However, due to the need for the machine to re-enter the field during operation, which can potentially cause secondary damage to the stubbles, and the lack of direct yield tests in the second season to verify the device's effectiveness in increasing production, further research and validation are required to assess its practical application.…”

SMR-RS: An Improved Mask R-CNN Specialized for Rolled Rice Stubble Row Segmentation

“…Studies have shown that lifting the stubbles that have been rolled by machines can effectively increase the yield of ratoon rice [8]. Based on this, Zhang [9] designed a chain row claw-type righting device for lifting the rolled rice stubble. Based on [9], Chen [10] et al…”

“…Based on this, Zhang [9] designed a chain row claw-type righting device for lifting the rolled rice stubble. Based on [9], Chen [10] et al…”