Impacts of Urbanizaiton on the Environment in China

Source: 

Wong, Q.  2001.  A remote sensing–GIS evaluation of urban expansion and its impact on surface temperature in the Zhujiang Delta, China.  International Journal of Remote Sensing, 22(10): 1999-2014.

The Zhujiang Delta region of China is one of the largest areas of economic concentration in Southern China, and as such has experienced rapid urbanization during the years since the implementation of China’s economic reform policies.  It is also one of the richest agricultural regions.  With the rapid urbanization process changing the land-use patterns of the region, and keeping in mind the Urban Heat Island phenomenon, in which urban areas tend ot have higher surface temperatures than surrounding areas, Wong attempted to use satellite imaging and GIS analysis technology to study the pattern of urbanization and determine its effects on the surrounding environment. 

Wong identified 7 types of land use using LANDSAT images of the region for both 1989 and 1997, and then quantified the changes land use between the two with a matrix.  These images were then overlaid in a GIS system to represent the data on land use changes in a single image detailing the overall changes.  Another layer, containing data on roads in the region, was added to the GIS system and a buffer was added to that data to determine the correlation between urbanization and the distance from major roadways. 

 

After that, radiant surface temperature data from each year, obtained from LANDSAT TM thermal infrared data, was added to the GIS system and an algorithm was used to determine the change between the 8 year period.  Combining these elements in the GIS system allowed for the spatial analysis of the correlation between urbanization trends and increases in surface temperatures between 1989 and 1997. 

 

 

This allowed Wong to conclude that not only has increased surface temperature correlated to increased urbanization, but also that greater urbanization has occurred in rural areas and in closer proximity to roadways.  It also presented interesting data regarding two other land uses.  Surface temperature increases were also correlated with barren land use as well as non-traditional horticultural lands, though to a lesser extent.  Higher temperatures were also found in certain water bodies, which Wong hypothesized might be a result of increased sediments and other particles in the water from greater urbanization and industrial run-off.  This demonstrates other potential uses of GIS analysis in determining impacts of urbanization and land use change on the environment.