Digital photogrammetry and GPS techniques for monitoring landslide surface deformation

Digital photogrammetry and GPS techniques have been applied and compared in the context of monitoring landslide surface movements. The results of the different monitoring methodologies applied in this study indicate that the rate of movement is on the order of a few centimetres per month with a slight acceleration following a period of intense prolonged precipitations. Particularly, excluding some points that show an anomalous velocity probably due to localised movements, the results of continuous GPS monitoring and rapid static surveys indicate a total displacement at the upper and central parts of the landslide ranging between 5 and 10 centimetres in six months. The accuracy achieved with the GPS measurements ranges from several millimetres to a few centimetres for static and kinematic observations respectively. The applied methodology is an efficient and cost-effective tool to determine and monitor landslide surface displacements. The kinematic GPS technique represents an efficient method to integrate aerial photogrammetry and to rapidly define landslide topography or changes in site morphology by generating precise DEMs of the area. These survey techniques may be applied to other structural and morphological settings. The real-time monitoring is well suited for integration with an alert system for landslide hazard management and for monitoring displacements of slow landslides in urbanized areas and sites of high societal value