A comparative study of urban expansion on Hong Kong and Macao special administrative region in the past three decades

The urban space expansion is an important indicator for measuring urbanization level. Based on one Landsat MSS image and three Landsat TM images, the urban built-up characteristic of Hong Kong and its impact on the peripheral land during 1973-2004 was analyzed. Meanwhile based on two Landsat MSS and five Landsat TM images, the urban built-up chacctersitic of Macao and its impact on the peripheral land during 1973-2004 was analyzed. The urban area was 59.95 km² in 1973 and increased to 207.70 km² in 2004, the built-up area increased by 147.75 km² during the past 31 years and expanded 4.77 km² per year. While, in Macao, the urban area was 6.45 km² in 1973 and increased to 22.47 km² in 2004, the built-up area increased by 16.02 km² during the past 31 years and expanded 0.52 km² per year. The built-up area of both Hong Kong and Macao expanded around the old area and did not present manifest change in a certain direction. The expansion rate was distinct from each other. The increased built-up area of Hong Kong originates from different land use type, of which about 33.28% converted from sea, and 13.34% converted from rural area and dependent factory, diggings land and other construction area. The other mainly came from arable that accounts for 39.93% of the whole added built-up area. The urban construction of Macao formed according the transport condition historically. The built-up area expanded homocentricly along with the newly built road. The built-up area located mainly in Macao peninsula and expanded towards two islands of Taipa and Coloane. The expansion rate was distinct in different time. Many factors have contributed to the urban land use changes. But four major driving forces, population growth, economic increase, transportation infrastructure improvement and institution and policy change, are the most important factors. Population growth can simulate the built-up area manif- - estly, the economic increase is the main impetus of the land use, and the transportation infrastructure improvement is the impetus for the urban expansion, while the institution and policy change determine the macroscopical development and expansion pattern in some degree.