Environmental evolution and landslide hazard assessment in high mountainous areas based on UAV multi-sensors

The vigorous development of geospatial information technology has not only achieved good results in land monitoring, but has also been gradually extended to other application fields. Hazards monitoring is one of the important applications. Geospatial information can be obtained through surveying and mapping technology, and through multi-temporal geospatial data, the production, migration and migration of debris deposits can be quantitatively evaluated in a reasonable time and space in catchment scale. In recent years, the development and integration of MEMS technology has contributed to the rapid development of UAV measurement. This goal can be achieved due to the advantages of UAVs, such as efficiency, timeliness, low cost, and easy operation in severe weather conditions. The real-time, clear and comprehensive low- and middle-altitude photos of the area can be used as the most basic and important spatial information for research and analysis. Based on the aforementioned technologies, we selected two specific landslide-prone areas for UAV photogrammetry data acquisition. The two sites of forestry road and nursery situated in the high mountainous forestry in southern Taiwan. In order to evaluate potential hazards and hazard monitoring, the multi-temporal high precision terrain geomorphology in different periods is essential, so as to assessment the hazards and for early warring. For these purposes, we try to integrate several technologies, especially by unmanned aircraft system imageries and existed airphotos, to acquire and to establish the geoinfomatic datasets. The methods, including, (1) Remote-sensing images gathered by UAS and by aerial photos taken in different periods; (2) field in-situ ground control points and check points installation and geomatic measurement; (3) 3D geomorphological virtual reality model construction; (4) Geologic, morphotectonic and landslide micro-geomorphologic analysis; (5) DTM of difference from multi-temporal dataset to evaluate the topographic and environment changes. The main achievements are four: a) UAV photogrammetry and accuracy analysis in the study area; b) Construction of a 3D terrain model in the study area; c) Geological survey of collapsed areas; d) Multi-year spatial information variation analysis. According to the findings, landslides activated continuously in different periods and different areas. In different sections of the riverbeds, different degrees of siltation or erosion have been identified, so regular monitoring and potential hazard assessment are still necessary.