随着城市建设的快速发展,老城区改造已成为城市发展的重点工程之一。福州市近十几年来对原有旧城区中的棚屋区进行了大规模的改造,改善原有的居住条件。利用遥感技术重点研究和评价了福州市苍霞片区棚屋区改造前后的热环境变化,利用系列Landsat TM影像反演了该区1986年、1996年和2006年的地表温度、不透水面和植被等信息,计算了城市热岛比例指数(URI),并对该区改造前后热岛效应的时空变化进行了全面分析,探讨了其产生的主要原因。研究表明,不透水面与地表温度呈指数相关关系,高不透水面比例地区温度上升比低不透水面比例地区更快。总的看来,福州市苍霞片区通过棚屋区改造,热岛效应有了明显的缓解,在这20 a间,城市热岛比例指数从0.648下降到0.245。福州市苍霞棚屋区的重新规划和改造对缓解该片区的城市热岛效应起到了积极的作用。
With the urban development, replanning and reconstruction of the old urban area have become key issues of the urban development. Over the past decade, Fuzhou City of Fujian Province, Southeast China, has paced up its reconstruction progress. The Cangxia District, located in the southwestern Fuzhou, was therefore replaned and reconstructed to improve people’s living conditions because the area was full of intensively-built shanties. In order to study the thermal environmental changes of the Cangxia District before and after the reconstruction, three Landsat TM images of 1986, 1996 and 2006 were utilized to perform feature extraction of thermal-related information of the area, such as land surface temperature (LST), impervious surface area and vegetation coverage. The quantitative analysis on the relationship between impervious surface and LST suggested there is a positive exponential relationship between the two factors. With the assistance of the Urban-Heat-Island Ratio Index (URI), digital image processing on the three multi-temporal images has revealed the spatial and temporal variations of the urban heat island effect (UHIE) in the study area from 1986 to 2006. The results show that after the launch of the reconstruction project for the shanty-dominated area, the UHIE in the area has been greatly mitigated. In the past 20 years, the URI has been decreased from 0.648 in 1986 to 0.245 in 2006 owing to the significant decrease in high-density impervious surface areas and notably increase in vegetation covers. Obviously, the reconstruction is beneficial to the UHI mitigation of the Cangxia District.
[1] Wilson J S,Clay M,Martina E,et al. Evaluating environmental influences of zoning in urban ecosystems with remote sensing[J].Remote Sensing of Environment,2003,86(2):303-321.
[2] Weng Q,Liu H,Liang B,et al.The spatial variations of urban land surface temperatures:Pertinent factors,zoning effect,and seasonal variability[J]. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing,2008,1(2): 154-166.
[3] Xian G,Crane M.An analysis of urban thermal characteristics and associated land cover in Tampa Bay and Las Vegas using Landsat satellite data[J].Remote Sensing of Environment,2006,104(2):147-156.
[4] Giridharan R,Lau S S Y,Ganesan S,et al.Urban design factors influencing heat island intensity in high-rise high-density environments of Hong Kong[J].Building and Environment,2007,42(10):3669-3684.
[5] 岳文泽,徐建华,武佳卫,等.基于线性光谱分析的城市旧城改造空间格局遥感研究:以1997~2000年上海中心城区为例[J].科学通报,2003,51(8):966~974.
[6] 李 鹍,余 庄.基于遥感技术的城市布局与热环境关系研究——以武汉市为例[J].城市规划,2008,32(5):75~82.
[7] 王伟武,李国梁,薛 瑾.杭州城市热岛空间分布及缓减对策[J].自然灾害学报,2009,18(6):14~20.
[8] Chander G,Markham B.Revised Landsat-5 TM radiometric calibration procedures and postcalibration dynamic ranges[J].IEEE Transactions on Geoscience and Remote Sensing,2003,41(11):2674-2677.
[9] Weng Q,Lu D,Schubring J.Estimation of land surface temperature-vegetation abundance relationship for urban heat island studies[J].Remote Sensing of Environment,2004,89(3):467-483.
[10] Nichol J.Remote sensing of urban heat islands by day and night[J].Photogrammetric Engineering and Remote Sensing,2005,71(5):613-621.
[11] Huete A R.A soil-adjusted vegetation index (SAVI)[J].Remote Sensing of Environment,1988,25(3):295-309.
[12] Xu Hanqiu.Analysis of impervious surface and its impact on urban heat environment using the Normalized Difference Impervious Surface Index(NDISI)[J].Photogrammetric Engineering & Remote Sensing,2010,76(5):557-565.
[13] Xu Hanqiu.Modification of Normalized Difference Water Index (NDWI) to enhance open water features in remotely sensed imagery[J].International Journal of Remote Sensing,2006,27(14):3025-3033.
[14] 徐涵秋,陈本清.城市热岛与城市空间发展的关系探讨——以厦门市为例[J].城市发展研究,2004,11(2):65~70.
[15] 佟 华,刘辉志,李延明,等.北京夏季城市热岛现状及楔形绿地规划对缓解城市热岛的作用[J].应用气象学报,2005,16(3):357~366.
