UAV based 3D modeling analysis in determining and preventing rockfall risks: A case study from Murtaza Village (Niğde, Turkey)

Abstract

In this study, rockfall risks in Murtaza village, which is located within the central district of Niğde province and where active rockfall events are experienced, were evaluated using a high-resolution digital terrain model (DTM) created based on unmanned air vehicle (UAV) images, field measurement data, and three dimensional (3D) rockfall models. During the field studies, 14 rock blocks that were in danger of falling were identified and geometric measurements for each of the rock blocks were made. By using field measurements, the rock blocks are modeled their geometric properties in the RAMMS program and a total of 1400 rockfall simulations, 100 from each of the modeled blocks were carried out on the high-resolution DTM. Thus, the kinetic energy, jump height, velocity, and fall trajectories of each rock block were determined. According to the results, the rock blocks that are close to the settlements are damped without being transported to very long distances. These blocks do not constitute significant risks since having values such as low energy, speed, and jump height. However, the rock blocks of equant shape and high volume, located on the northwest slopes above the settlements, constitute a significant risk. These rock blocks move for long distances depend on their geometric properties and geomorphological characteristics of the study area and their energy is absorbed in contact with houses, roads, etc., structures, or in places where the slope decreases on the topography. To prevent the danger of rock blocks in this area, retaining walls have 142 m long and 1.5 m wide were created within the rockfall models. According to the results of these models, while a 5 m high retaining wall in areas close to the source of rock blocks, a 3 m high retaining wall far from the source areas stops the progress of the rock blocks.