RAPID TERRAIN ANALYSIS IN LANDSLIDE ZONES: GPR AND AIRBORNE PHOTOGRAMMETRY AS A COMPLEMENT FOR THE LEVELLING DATA. CASE STUDY NEAR POIANA RUSCĂ DAM, ROMANIA

This paper investigates rapid terrain analysis in landslide-prone areas, emphasising a case study near the Poiana Ruscă Dam, Romania. The research integrates Ground Penetrating Radar (GPR) and airborne photogrammetry, complemented by traditional levelling data, to assess a known landslide with small dimensions on the southwest side of the Poiana Ruscă Lake, near the dam‘s upstream side. This landslide is part of an annual topo-geodetical monitoring campaign due to its potential impact on the dam‘s stability. The study utilises a compact drone to generate orthophotomosaics and Digital Elevation Models (DEMs) for the road sections above the landslide, identified in topo-geodetical records. This method offers high-resolution surface deformation data, providing a clear view of the impact on the affected road. The GPR method, employing a 200 MHz antenna, plays a crucial role in revealing subsurface details, particularly in areas where traditional levelling surveys face challenges due to disappearing benchmarks caused by terrain movement. This method effectively highlights areas of interest in the form of potential subsidence areas and voids, correlating with surface observations. Notably, the GPR data indicates stronger signal attenuation at relatively shallow depths, suggesting alterations in the subsurface composition and moisture content. These findings are critical for understanding the landslide‘s structural characteristics and its ongoing dynamics. This research demonstrates the synergy of GPR, airborne photogrammetry, and levelling data in providing a comprehensive analysis of landslide zones at a relatively fast and efficient pace. It emphasises the importance of integrating various technological approaches for effective monitoring and management of such geohazards, particularly in the context of maintaining the safety and integrity of hydropower dams and their surrounding infrastructure.