Landslide displacement and activity monitoring based on UAS multi-sensors

Due to Taiwan's high seismicity and heavy rainfall, numerous landslides have occurred, causing severe damage. These landslides pose long-term threats to human life, property, and the environment. As a result, significant research has focused on assessing landslide hazards and developing mitigation methods. Key areas of study include the size, volume, recurrence, and evolution of landslides. The rapid advancement of geospatial information technology has greatly improved land monitoring and expanded into other applications, including hazard monitoring. Geospatial data, obtained through surveying and mapping, allows for the quantitative evaluation of debris production, migration, and deposition over time and space at the catchment scale. In recent years, MEMS (Micro-Electro-Mechanical Systems) technology has played a key role in advancing Unmanned Aerial Systems (UAS) for measurements, offering advantages such as efficiency, timeliness, low cost, and ease of use in harsh weather. Real-time, high-resolution aerial images provide essential spatial information for research. This study used UASs to monitor a landslide area in Baolai Village, southern Taiwan, which was severely affected by a catastrophic landslide triggered by Typhoon Morakot in 2009. To assess hazards, the study combined UASs, field surveys, terrestrial LiDAR, and UAS LiDAR for data collection beginning in 2015. Since early 2018, UAS LiDAR technology has been used to scan the area. Changes in the landscape were measured and verified using Ground Control Points (GCPs) and Check Points (CPs). The results showed that the most active regions are on the eastern side of the landslide. Significant elevation changes were detected before mid-2017, but activity increased again in 2018 and intensified after 2021.The study provides valuable geospatial datasets for hazardous areas, as well as essential geomorphological data and methods that can support future research, hazard mitigation, and planning.