Application of UAV photogrammetry and electrical resistivity tomography for characterization of a complex landslide: a case study from northwest Himalayas, Pakistan

Landslides are a destructive natural phenomenon that can cause significant damage to landscapes, infrastructure, and human lives around the world. The Himalayas, with their active tectonics and varied climatic conditions, are particularly susceptible to landslide hazards. The Danna-Sahotar Landslide in the district of Muzaffarabad, Pakistan, is a prime example of this. Triggered by prolonged rainfall in April 2016, this mass movement caused extensive damage to the area's infrastructure and continues to pose a threat to nearby settlements. To better understand the nature of the Danna-Sahotar Landslide, an integrated approach was used, combining unmanned aerial vehicle photogrammetry and electrical resistivity tomography (ERT) techniques. High-resolution orthomosaic and digital surface model were generated with a spatial resolution of 3 cm/pixel and 6.14 cm/pixel, respectively. These data were then used to analyze the geological, geomorphological, and geometric characteristics of the landslide. The results of this study reveal that the Danna-Sahotar Landslide has multiple failure mechanisms, making it a complex and active mass movement. The ERT results indicate that the sliding mass of the landslide primarily consists of moisture-induced colluvium and debris, which leads to low resistivity in resistivity tomograms. The moisture content of the slope-forming material is a significant contributor to the instability of the landslide. Additionally, a well-developed linear to curvilinear slip surface between the unconsolidated sliding mass and bedrock was identified based on resistivity contrast. In conclusion, this study highlights that, in addition to active tectonics, the hydrogeology of the slope-forming mass is a major factor in reducing the stability of the Danna-Sahotar Landslide. The results of this integrated study can be used to develop effective mitigation measures to prevent future catastrophe.

Automated summary

Landslides can cause significant damage to landscapes, infrastructure, and human lives globally. The Himalayas are particularly vulnerable to landslide hazards due to their active tectonics and diverse climatic conditions. The Danna-Sahotar Landslide in Muzaffarabad, Pakistan, serves as an example of the devastating impact of landslides on infrastructure and settlements. By utilizing unmanned aerial vehicle photogrammetry and electrical resistivity tomography techniques, a comprehensive understanding of the landslide was achieved, highlighting its multiple failure mechanisms and the role of hydrogeology in reducing stability.