Assessment of Horizontal Displacements in a Large Landslide in the Eastern Rhodope Mountains (South Bulgaria) Using Remote Sensing

摘要

This study presents the results of measurements of horizontal displacement for a large landslide located in a mountainous area in Southern Bulgaria that was most active in 2000. The landslide has an extensive area of 1.6 km~2. For that reason it was very difficult to define the magnitude of the horizontal displacement and even its direction for a long period of time. Aerial and satellite images with very high resolution (VHR), acquired before and after the landslide began to move, were used to measure the horizontal movement of the landslide. The aerial photos were acquired in 1996 and the WorldView-1 satellite image was acquired in 2008. Both images were subject to photogrammetric processing for orthorectification purposes. The aerial photos were mosaiced to produce an overall orthophotoplan. The horizontal displacements that occurred during the period between the two acquisitions were established by measurement of the differences in the coordinates of objects identified on both images. The average length of the horizontal vectors between the two locations was 27-28 m, while the maximum was up to 40 m. A landslide displacement value map was composed.