DaNang City in Central Vietnam underwent a strong urbanization process. A declassified satellite image of 1977 and a GeoEye image of 2013 illustrate the change of the settlement structure. Landsat images of 1990, 2001 and 2007 show a period of rapid urbanization, which is still ongoing.
The black and white image (left side) was taken by a KH-9 Hexagon satellite (3rd generation) at 15-08-1977. The satellites nickname is ‘Big Bird’ and it was part of a U.S. spy satellite program which lasted from 1973 to 1980. The image has a high ground resolution of about 6 m². The secret images which were used for reconnaissance of the U.S. intelligent agencies were declassified in 2002. The data is available from the U.S. Geological survey.
The image color image (right side) shows a GeoEye satellite image take at 20-04-2013. It is a high resolution image with 0.5 m² ground resolution.
The comparison of both satellite scenes shows consistency as well as change of the city. Rural villages in the Lien Chieu and the Cam Le districts prescribe the later growth of the city. An industrial area in Lien Chieu already exists in 1977. Son Tra and Ngu Hanh Son districts, which are today dominated by a rapid development of tourism infrastructure like hotels and resorts, are characterized by military installations in 1977. The building structure of the central districts Thanh Khe and Hai Chau underwent an intense densification.
Landsat satellite images are a valuable source for change monitoring. For this analysis three Landsat TM and ETM+ images of 1990, 2011 and 2007 were used to drive information on the land-use and land-cover. The step-by-step comparison of the classification maps allows a land-use change detection. The result identifies an intense phase of urban sprawl.