High Resolution Landscape Change Analysis with CORONA KH-4B Imagery. A Case Study from Iron Gates Reservoir Area

Abstract

Mapping landscape change at detailed scales is an interesting task when the focus is not only the land cover change. The paper proposes the integration of a diachronic imagery set in a GIS application in order to obtain precise maps of the key qualitative changes along a representative sector of the Danube River Defile where the Iron Gates emerged between 1965-1972 to the border between Romania and Serbia. A photogrammetric process approach was developed for the building of precise historical orthophoto coverage on the basis of a CORONA KH-4B/ DECLASS-1 dataset. This was focused on reconstructing the image geometry and building a precise orientation, together with an aerial triangulation operation. The results were a Digital Surface Model and an orthophoto (about 5 m average geometric accuracy). This data was integrated into a GIS project with vector data extracted from the latest orthophotos (0.5 m, by ANCPI Bucharest) for mapping of landscape changes as an effect of the complex hydrotechnical works. The Iron Gates reservoir level was of about +33 m higher at the beginning of the 1970s in comparison with the primary Danube River level, the road and the railroad moved upslope like Orşova town and other villages. The most dramatic change was related to the total flooding of Ada-Kaleh Island with a Turkish settlement and a Vauban system fortress, an interesting historical and cultural site.