New Technologies for Geological Disaster Monitoring and Early Warning—Integrated Space–Air–Ground Solutions to Address Challenges in Geological Disaster Prevention and Control

China is among the countries in the world most severely affected by geological hazards and with the largest population at risk. Geological hazards are characterized by a wide variety of types, extensive geographic distribution, and complex features. To implement General Secretary Xi Jinping’s directive to “establish an efficient and scientifically sound system for the prevention and control of natural disasters and enhance society’s overall capacity for such prevention and control,” China is following a four-step work plan—conducting research on underlying principles, identifying potential hazards, monitoring these hazards, and issuing early warnings—and focusing on key areas and weak links to comprehensively strengthen capabilities in geological hazard risk assessment, targeted hazard identification, integrated monitoring, as well as early risk detection and forecasting and early warning.

So, how can we best clarify the core issues in geological hazard prevention and control—namely, “where are the potential hazard locations” and “when might a hazard occur”? Recently, experts including Professor Zhang Qin from the School of Geological Engineering and Surveying Engineering at Chang’an University and Associate Professor Li Jiachun from the Institute for Road Disaster Prevention and Control at the School of Highway Engineering have discussed, based on practical experience, the current status and development trends of early identification and monitoring–early warning technologies for geological hazard risk points in China.

The “Three Inspections” system has identified a large number of potential geological hazard sites.

Currently, 282,000 potential geological hazard sites have been identified nationwide, posing a threat to the lives of approximately 20 million people and to property valued at RMB 450 billion.
According to statistics from the relevant authorities, since the 1990s China has conducted comprehensive and systematic detailed surveys of geological hazards, as well as multiple rounds of exhaustive, blanket inspections targeting potential hazard sites. Given the large number and wide distribution of such sites, past survey efforts have primarily focused on urban areas and major infrastructure projects, employing methods such as identifying specific hazard locations and conducting routine inspections during the flood season. However, due to the limitations of these survey methodologies, the vast majority of major geological disaster events that have occurred in recent years have not been located within the scope of the pre-established contingency plans.
According to the Regulations on the Prevention and Control of Geological Hazards issued by the State Council in 2003, geological hazards encompass disasters associated with geological processes, such as rockfalls, landslides, debris flows, ground subsidence, ground fissures, and land settlement. Typically, rockfalls, landslides, and debris flows occur rather suddenly and are therefore classified as sudden geological hazards, whereas ground subsidence, ground fissures, and land settlement generally develop and unfold more gradually and are thus referred to as gradual geological hazards. Li Jiachun explained that surface deformation involves issues of scale and research scope; accordingly, different monitoring methods must be employed depending on the scale of the monitored objects and the required level of accuracy.

▲ Schematic Diagram of Integrated Space–Air–Ground Monitoring

At present, in the field of geological disaster monitoring and early warning, the Ministry of Natural Resources emphasizes the need to comprehensively employ a variety of cutting-edge technologies, including synthetic aperture radar interferometry, high-resolution satellite remote sensing, UAV-based aerial surveying, and airborne LiDAR mapping, to further enhance the nation’s capacity for geological disaster prevention. This approach is also embodied in the “three-inspection” integrated air–space–ground system proposed by Professor Xu Qiang, a renowned expert in geological disasters and Executive Deputy Director of the State Key Laboratory of Geological Disaster Prevention and Geological Environmental Protection at Chengdu University of Technology.
Specifically, the process begins by leveraging high-resolution optical imagery and InSAR to identify areas that have previously experienced significant deformation and failure as well as those currently undergoing deformation, thereby conducting a regional, survey-style census of potential major geological hazard risks. Subsequently, airborne LiDAR and UAV aerial photography are employed to carry out detailed investigations of the topography and landforms, surface deformation and failure indicators, and even rock mass structures in high-risk zones, areas with concentrated hazard distributions, or specific major geological hazard risk points, thus enabling a thorough examination of these hazards. Finally, ground-based verification surveys combined with in-situ observations of both the surface and subsurface slopes are conducted to validate and confirm—or rule out—the findings from the preliminary census and detailed investigation, thereby achieving a comprehensive verification of major geological hazard risks. Currently, the use of unmanned survey vessels and multibeam echo sounders further extends this approach to aquatic environments.
According to reports, Professor Xu Qiang’s team has deployed an integrated space–air–ground “three-inspection” system for demonstration applications in provinces such as Sichuan and Guizhou, achieving promising results. In Guizhou Province, InSAR and airborne LiDAR were used to conduct specialized hazard assessments across the entire province, identifying 2,000 new potential geological hazard sites, nearly 900 of which are high-altitude, concealed hazards. In Sichuan Province, a combined approach using InSAR and optical remote sensing was employed to systematically screen a 60,000-square-kilometer area designated as high-risk for geological hazards, uncovering 840 newly identified deformation zones; subsequent on-site verification confirmed that more than 70% of these zones exhibit significant deformation.

It is essential to recognize that modern remote-sensing technologies—such as optical remote sensing, InSAR, LiDAR, and UAV photogrammetry—each possess unique strengths and capabilities; however, they are also subject to specific limitations and drawbacks. Therefore, relying on a single technological approach alone is insufficient for addressing the identification of disaster hazards. The challenge facing professionals today is how to effectively integrate these diverse techniques.

High-precision monitoring system enables timely early warning and forecasting.

At present, technologies for the automated on-site acquisition of various monitoring parameters—such as displacement, stress, soil moisture content, water levels, and rainfall—and for the remote wireless transmission of these data have all reached a mature stage in both surface and subsurface monitoring of geological hazards. However, objectively speaking, early warning and forecasting of geological hazards remain an international challenge, and it is still not possible to accurately predict the timing of such events in advance. That said, for most geological hazard systems that are already subject to scientific and professional monitoring, it is feasible to issue warnings several hours or even just a few minutes before an event occurs.
On February 19, 2018, a landslide occurred on the Zhouzhi section of Highway G108, with over 30,000 cubic meters of earth and rock collapsing down the slope, instantly destroying the roadway and disrupting traffic. Fortunately, the team led by Li Jiachun issued a red alert five days in advance, thereby averting major traffic disruptions and casualties. This successful monitoring and early warning represents Shaanxi Province’s first such case and serves as a typical example of how highway authorities can effectively mitigate and prevent disasters through early warning systems and emergency response measures.
On March 26 of this year, a loess landslide with a volume of approximately 20,000 cubic meters occurred in Dangchuan Village, Yanguoxia Town, Shuijing County, Gansu Province.

▲Overall view of the Dangchuan No. 6 Landslide in Gansu Province on March 26, 2019

A joint monitoring and early-warning system led by Professor Zhang Qin’s research team and Professor Xu Qiang’s team at Chengdu University of Technology issued a yellow alert for the landslide two days in advance, an orange alert one day in advance, and a red alert 40 minutes in advance. Relevant authorities promptly implemented appropriate preventive measures, resulting in no casualties or property damage. A remote video-monitoring device installed on the sliding mass captured the entire process of the landslide event.

Recently, Professor Zhang Qin’s research team used InSAR monitoring technology to detect an accelerating landslide threat in a village of several hundred households in Leibo County, Liangshan Prefecture, Sichuan Province. The team promptly reported the relevant monitoring data and information to the pertinent departments of the Ministry of Natural Resources, whereupon the local government immediately implemented response measures.
According to Li Jiachun, nationwide efforts based on community-based monitoring and prevention have, through the gradual establishment of a “comprehensive, round-the-clock, multi-factor, multi-scale” monitoring system, amassed vast amounts of observational data. Given the complexity and diversity of both the monitored phenomena and the monitoring techniques employed, the most significant challenge currently facing researchers in the field of geological hazard prevention and control is how to effectively analyze and process field monitoring data and, on the basis of such data, develop models that can provide timely and accurate early warnings and forecasts of hazard occurrence.
He emphasized that geological hazard prevention and control is indeed a broad-ranging, highly specialized undertaking with a long operational chain and stringent professional requirements, necessitating in-depth research into hazard mechanisms throughout the entire process and repeated analysis based on data.

More Technological Breakthroughs Are Needed in Geological Disaster Prevention and Control

Currently, among the successful disaster-warning cases nationwide, an increasing number rely on professional early identification of geological hazards and subsequent effective warnings. This is attributable, on the one hand, to the integration of expertise and technologies from multiple disciplines, including surveying, engineering geology, remote-sensing geology, and computer science; and, on the other hand, to the increasingly sophisticated processing of multi-source data, encompassing optical remote sensing, InSAR, LiDAR, UAV-based aerial surveying, as well as various ground-based and in-situ monitoring datasets for slope interiors.
Li Jiachun believes that throughout world history, numerous landslides and other geological hazards have occurred; however, the vast majority of recorded cases are limited to macroscopic, straightforward data, such as the volume of the hazard mass and the number of casualties. With the accumulation of quantitative data, substantial investment, and advances in technology, a large volume of robust, multi-source monitoring data on geological hazards will be generated. By leveraging artificial intelligence for autonomous learning and comprehensive analysis of this data, it is only a matter of time before highly accurate early warnings and forecasts can be produced.
With advances in technology, a wide range of methods and tools are now available for geological disaster monitoring and early warning. Zhang Qin began researching the application of InSAR technology to geological hazard monitoring in 2003; it is precisely due to the pioneering efforts of this early cohort of researchers that InSAR has become an exceptionally effective and crucial tool for identifying and detecting geohazards undergoing deformation—particularly in recent years, where its demonstration applications have yielded remarkable results.

▲On March 24, 2019, the BeiDou/GNSS monitoring system issued a two-day early warning for a loess landslide in Gansu Province, resulting in no casualties. Schematic map of the landslide area (red areas indicate villages, and yellow areas mark the locations of BeiDou GNSS monitoring stations).

Many large-scale, high-risk geological hazards are located on steep mid-to-upper slopes of mountainous terrain, making them difficult for investigators to access. Some hazard risks are even situated in remote, sparsely populated areas or uninhabited regions, leaving responders virtually powerless once a disaster strikes. In response to this challenge, Zhang Qin recently proposed a solution of deploying sensor payloads in these hard-to-reach areas: “This approach not only meets precision requirements but also boasts a very low cost, making it the future trend in the development of monitoring sensors.”

The monitoring and early warning system for sudden loess landslides in Gansu Province is implemented using a newly developed, cloud-based, low-cost (priced at around RMB 1,000) but high-precision BeiDou/GNSS monitoring system created by Professor Zhang Qin’s research team. Preliminary validation has confirmed the reliability of the associated algorithms as well as the software and hardware components of the system. This monitoring and early warning system represents the initial research outcomes of two major projects: the National Natural Science Foundation Key Project “Landslide Identification and Intelligent Monitoring and Early Warning Based on Space–Air–Ground Technologies,” led by Professor Zhang Qin’s team, and the National Key R&D Program project “Real-Time Monitoring and Early Warning of Mega-Scale Landslides and Development of Corresponding Technological Equipment.” The successful early warning issued this time has also laid a solid foundation for subsequent efforts in the monitoring, early warning, and technological equipment development related to landslides and other sudden geological hazards.

Over more than two decades of research, Zhang Qin has consistently sought innovative solutions to the myriad challenges she has encountered, rigorously testing and validating each approach through repeated experimentation. She emphasizes: “It is essential to break free from conventional thinking, avoid confining oneself to a single field, and adopt a broader, more expansive perspective. First, dare to think boldly; second, identify the most difficult problems. With persistent effort, a solution will always be found.”

On the topic of trends in the development of geological hazard monitoring and early-warning technologies, Zhang Qin stated: “We should not expect technology to deliver instant, one-step solutions to every problem. What matters is that we keep making progress. Science is the cumulative result of generations of effort; as long as we move forward, our work has value, and humanity’s capabilities grow stronger in the process.”

Geological hazard prevention and control is a protracted battle that cannot be permanently resolved in one fell swoop. The Ministry of Natural Resources has proposed that, starting in 2018, efforts will be made over approximately three years to refine institutional mechanisms, increase investment, and establish a comprehensive geological hazard prevention and control system, thereby effectively enhancing China’s capacity to defend against geological hazards and reducing the occurrence of major casualties caused by such disasters. Geological hazard monitoring and early warning constitute an essential component of this prevention and control system; the priority should be to strengthen technological support, leverage modern technologies, and build and improve an interconnected national, provincial, municipal, and county-level platform for geological hazard monitoring, information dissemination, and early warning, as well as an emergency dispatch and command system.
China faces a large number of geohazard sites spread across a wide area. For routine geohazards, manual surveys and community-based monitoring and prevention remain indispensable. Only by integrating these efforts with professional monitoring and early-warning systems—so that they complement and cross-verify one another—can we maximize our ability to identify potential geohazard risks.