Multi-temporal analysis of urban area changes using Built-up Index

The population of Istanbul has increased rapidly in the last three decades similar to other metropoles of the world. While the population in 1980 was around 4.7 million, it exceeded to 15 million in 2015. The city has been affected from population growth and rapid urbanization, and the land cover/use characteristics of Istanbul changed very fast. In consequence of unplanned urbanization, rapid land use/cover changes caused heterogeneity in urban texture. Increasing urbanization and spatial expansion of the urbanized areas caused land changes from natural landscapes to impervious surfaces. This paper aims to determine the multi-temporal change of urban texture in Istanbul metropolitan area using Normalized Difference Vegetation Index (NDVI) and Normalized Difference Built-up Index (NDBI) focusing on district level. The study was conducted using Landsat TM images of Istanbul respectively acquired in 1984, 2002 and 2011. An automated water extraction index (AWEI) is used to extract water bodies from study area. To obtain district level index images, all derived index images are clipped using the district administrative borders. The results indicate that significant increase in impervious surfaces is identified along with a considerably decrease in vegetation in some districts of Istanbul between 1984 and 2011.