## 4 Conclusions  
The key to ensuring the accuracy of impervious surface extraction is to reduce the confusion between impervious surfaces and bare soil. In the process of realizing the impervious surface extraction in Xuzhou City, the farmland distributed in the middle of Xuzhou City has the greatest influence on impervious surface extraction accuracy. In order to minimize the influence of soil on impervious surface extraction accuracy, Xuzhou City was divided into built-up and non-built-up areas. Only in the built-up area was the Impervious Surface Index used to establish dense and correct impervious surface samples, and supervised classification was used to realize the extraction of impervious surfaces. The final impervious surface extraction accuracy of impervious surfaces is not less than 83.46%, and the Kappa coefficient is not less than 0.85. (1) Analysis of spatial and temporal changes in impervious surfaces in Xuzhou City. The impervious surface area increased by 637.17 km\({}^{2}\) from 2013 to 2022. The 2014-2016 and 2018-2022 growth rates were faster, and the impervious surface growth rates were similar from 2014 to 2016 with growth rates of 6.33% and 6.37%, and 2018-2021 with growth rates of 4.38%, 4.98%, and 3.65%. The growth became slower in 2017-2018 and 2021-2022, with growth rates of 0.51%, 0.47%, and 0.52%, respectively, increasing by 10.10 km\({}^{2}\), 9.17 km\({}^{2}\), and 11.69 km\({}^{2}\). The distribution of impervious surfaces in Xuzhou City Municipal District City is the most dense, and Feng County has the smallest percentage of impervious surfaces. Tongshan County had the largest increase in impervious surfaces, with an increase of 112.74 km\({}^{2}\), and Feng County had the fastest growth rate of impervious surfaces at 94.15%, with an increase of 98.99 km\({}^{2}\). (2) Influence of impervious surface distribution on surface temperature in Xuzhou City. From 2013 to 2022, more than 50% of the impervious surface areas in Xuzhou City were either high-temperature or sub-high-temperature zones. Calculating the average temperature by zones, it was found that the temperature in the aggregated impervious surface areas was higher than the temperature in other impervious surface areas, and the average temperature in the permeable surface area was the lowest. Samples were selected in and around impervious surface aggregation areas to calculate their average temperatures and impervious surface densities, regression analyses were performed, and the impervious surface densities were proportional to the average surface temperatures. The increase in impervious surfaces and the decrease in vegetation and bare soil are the inevitable results of urban expansion, but maintaining a favorable urban environment is a prerequisite for ensuring the quality of life of residents. Impervious surfaces are one of the most important factors affecting the surface temperature of the city, so it is important to monitor the temporal and spatial changes in impervious surfaces and the surface temperature of the  
Figure 6: Regression analysis of impermeable surface density and average temperature. city. The timely adjustment of the pace of urban development can reduce the impact of urban development on the environment. (3) In addition, this paper also has limitations. The selection of impervious and permeable surface samples by thresholding is affected by the spectral texture features of the image as well as the level of visual interpretation. Therefore, further research should be carried out on the method of the automatic acquisition of thresholds in order to improve the accuracy of impervious surface extraction. Meanwhile, the surface temperature is affected by many aspects, such as vegetation rate and elevation. In this paper, there is a limitation that only the impervious surface aggregation area and its surrounding areas are included in the study area. The influence of various factors should be considered in future research.