Determining the temporal changes of land use by using orthophotos: the sample of Elmali basin

Abstract

Water basins, which are used as the main drinking and domestic water resources in large cities, are polluted by excessive settlement, industry and agriculture. Thus it is important to take some protection precautions in catchment basins for both surface and underground water. In this study, the temporal changes of forests and cultivated lands as well as the settlements in water basins subjects were briefly explained and a sample application which uses real data were examined to demonstrate those explained contents. In order to extract temporal changes, orthophotos taken over years have been used as the base dataset. By this way, the temporal land use in the same region was determined. The study area involves Cavusbasi region of Beykoz district of Istanbul and Elmali basin located in that region. The extracted information from temporal dataset may also be used for effective future planning purposes. This paper uses historical dataset between the years 1946 and 2013 to extract information to be used for the future projections. This dataset contains six different historic time intervals. Results from the analyses of the study show that there is a remarkable increase in urban areas especially since 1990s. This increment has caused a significant decrease in forest and cultivated areas. According to the juridical regulations, it is not allowed to construct buildings in absolute and short-range protection areas. However this study shows that an area of 4.0126 km2 (approximately 400 hectares) unauthorized structures was developed against to these regulations.