Istanbul, one of the largest metropolitan cities in the world, experienced rapid industrialization and urbanization in the second half of the 20th Century. The city grew at an average annual growth rate of 4.5% between 1950 and 2000. Growth of settlements and damage to the natural environment are among the most important problems caused by the transportation system. Istanbul is located on both sides of the Bosporus Strait that connects Europe to Asia. An alternative to the recently planned third bridge at the Istanbul Metropolitan area was selected. Transportation infrastructures that were constructed drastically changed the land-use profile and caused negative impacts on the environment. The proposed third bridge route will threaten agricultural areas, forests, water and water collection areas that form the open space systems of Istanbul.
The aim of this study is to analyze the effects of existing Bosporus bridges on the spatial development and the natural resources of the metropolitan area of Istanbul. With the new transportation axis over the bridge route, the potential impacts on vital open spaces such as the northern forest regions, the existing agricultural lands and the water basins are also evaluated. These changes are evaluated using a Geographical Information System (GIS) and five Landsat satellite images from 1975, 1990, 1995, 2000 and 2005. The proposed method will provide a better understanding of the main reasons for the effects and will support city administrators in similar projects.