Spatio-temporal Analysis of Urban Built-up Land in the Hanoi Metropolitan Area (Vietnam) using Remotely Sensed Images

Rapid and unplanned urbanization leads to temperature rise, urban vegetation decrease, and built-up land increase, forming an urban heat island. It is, therefore, the change of built-up land plays an important role in surface urban heat island studies. This study aims to analyze spatio-temporal changes of urban built-up land in the Hanoi Metropolitan Area (HMA), Vietnam, using Landsat remotely sensed images acquired in 1996 and 2016. Landsat time-series images were first pre-processed preprocessed to account for sensor, solar, atmospheric, and topographic effects. Urban built-up land was then extracted based on an NDBI based continuous built-up index (BUc). Spatio-temporal changes of built-up land were finally analyzed by means of Geographic Information System (GIS). It was found that the urban built-up land area had increased from 4063.1 hectares in 1996 to 7163.2 hectares in 2016 which account for 13.3% and 23.4% of the total area, respectively. The built-up land area had increased by about 10.1% of the total area in 20 years. On average, 0.5% of the urban built-up area increases each year. The urban built-up land tends to expand to the west, southwest, and south of the HMA. These findings demonstrate the effectiveness of the proposed method for spatio-temporal analysis of built-up land in urban areas using remotely sensed images.