## 3 A Comprehensive Monitoring System for Landslides in 'Space-Sky-Ground-Underground'
### Temperature distribution inside inclinometer tubes B1, B3, and B5  
In summary, monitoring technology based on various dimensions of space, sky, ground, and underground is significant for landslide monitoring, early warning, and prevention. However, limited by the monitoring scope, equipment performance, and monitoring system robustness, for actual landslide monitoring under complex geological conditions and environments, it is often difficult to fully complete the monitoring task with a single monitoring technology. For example, InSAR technology in space-based monitoring is susceptible to the influence of atmospheric and vegetation cover, resulting in certain uncertainties in monitoring results. UAV technology in sky-based monitoring is generally challenging to operate in harsh weather conditions such as heavy rainfall; so, it is difficult to apply for landslide monitoring under rainfall conditions. Three-dimensional laser scanning technology in ground-monitoring is prone to errors in landslide monitoring with complex terrain structures, resulting in a significant decrease in the accuracy of test results. Although DFOS technology in underground-based monitoring can achieve large-scale and real-time monitoring, there is often a problem of sensor damage when landslides undergo a large deformation. Therefore, researching the inte  
Figure 16: Deep optical fiber monitoring profile of landslides [44]. Figure 15: Deep optical fiber monitoring profile of landslides. of 'Space-Sky-Ground-Underground' in all dimensions complements the advantages of multi-dimensional monitoring technology, and the limitations of a single monitoring technology in various landslide monitoring situations. In this way, achieving comprehensive, high-precision, and continuous monitoring of landslides is natural. On this basis, the advanced machine learning algorithms could be combined to improve the processing speed and utilization rate of massive monitoring data. After that, landslide hazard development trend prediction could be conducted to provide a reference basis for landslide hazard monitoring, early warning, and scientific control. Monitoring of the Xinpu Landslide in the Three Gorges Based on the 'Space-Sky-Ground-Underground' Monitoring Technology  
As the vital waterway for China's water transportation and the barrier to ecological protection, the Three Gorges Region of the Yangtze River plays a crucial role in promoting China's economic development and regulating regional environmental balance. However, as it is located on the northern edge of the Yangtze Plate, connected to the Qinling Mountains, Sichuan Basin, North China Plate, and South China Fold Belt, it has complex geological structures and frequent tectonic activities, resulting in various geological disasters such as landslides, collapses, and mudslides. Since the completion and impoundment of the Three Gorges Dam in 2003, the frequency of earthquakes in the reservoir has increased to more than ten times that before the impoundment. At the same time, it has also caused specific changes in regional temperature. Multiple influencing factors such as climate change, engineering disturbance, the rise and fall of the reservoir water level, and their combined effects have exacerbated the further deterioration of the regional geological environment, leading to the frequent occurrence of various large-scale and destructive landslide hazards. To ensure the transportation of the Yangtze River Three Gorges waterway and the safety of local people's lives and property, a large number of on-site experiments have been conducted. The applicability and advantages of various multi-dimensional monitoring technologies in the field of landslide hazard prevention and control are verified. The Xinpu landslide is in Anping Town, Fengjie County, Chongqing, China (Figure 17). It is a super large landslide composed of multiple deformation zones (with a land-slide area of 0.86 km\({}^{2}\), and a volume of 5.4 \(\times\) 10\({}^{7}\) m\({}^{3}\)). The slope is of low-to-medium mountain valley landform.