Study On The Information Extraction Of The Urban Heat Island, Run-Off And Impervious Surface In Xiamen City Of SE China With Remote Sensing Technology

With the fast development of the global economy, the urbanization has been accelerated all over the world. The urbanization has brought about the benefit to the whole human society, but also resulted in the negative impact on the global eco-enviromental system. Of the negative impact, the changes of urban climate and hydrologic system are two major aspects. Therefore, this thesis aims to study the interaction among various factors, such as urban expansion, landuse change, urban heat island, impervious surface and run-off, with the more concentration on the last three factors which are more closely related to the urban climatic and hydrological system. Xiamen City in SE China was taken as an example for the study. Remotely-sensed data were the major data source, one from a Landsat TM image aquired on May 17, 1996, the other from an ASTER image dated on Sep 6, 2002. The goal was achieved using by the following steps. Firstly, the study extracted the urban built-up area based on an index-drived image composed of Modified Normalized Differences Water Index (MNDWI), Soil Adjusted Vegetation Index (SAVI) and Normalized Differences Built-up Index (NDBI). The results reveals that the urban built-up area increased by 46.09 km~2 from 1996 to 2002, due largely to population growth, economic development and increasing foreign direct investment. Secondly, urban heat island distribution of the city was revealed by using a brightness temperature calibration model. The result indicates that heat island area has increased by 23.32 km~2, spatially distributed along with the urban expanded areas. Thirdly, impervious surface of the Xiamen Island was extracted by using a linear spectral unmixing model. This reveals that the impervious-surface area has also increased with the urban expansion. The annual increase rate is 5.19%. Acompanied with the impervious surface increase, rainfall and run-off also changed. So fourthy, the SCS (soil conservation service) method was used in this thesis to model the rain-runoff relationship. The result shows that the expansion of the built-up area has caused the increase of average runoff volume. Obviously, the impervious surface, brightness temperature and runoff coefficient all have increased along with the urban expansion. Finally, it can be concluded that the urban expansion is the chief reason for the urban heat environment change of Xiamen City during the study years.