New technologies make geological hazard prevention and control in China more intelligent
Dong Hui Qiu Guanyong
There is an ancient saying: "Reading the land is like reading a person." If we really compare the earth to a person, we have not yet fully understood this "person's" temperament and nature. Landslides, debris flows, and other geological disasters triggered by earthquakes, rainfall, and engineering activities occur frequently. According to statistics from the Ministry of Land and Resources, in the first half of 2013 alone, there were 4,049 geological disasters nationwide, causing 250 deaths or disappearances and direct economic losses of 1.02 billion yuan. A total of 148 geological disasters were successfully forecast nationwide, avoiding casualties to 7,514 people and preventing direct economic losses of 240 million yuan. Compared to the same period last year, the number of geological disasters, deaths and disappearances, and direct economic losses all increased in the first half of this year.
From the data perspective, there is a huge gap between the number of successful geological disaster forecasts and actual occurrences. Are we really powerless to watch the "earth" have a temper? Modern technology is developing rapidly, and informatization levels are steadily improving. What can these do for geological disaster monitoring and early warning? What role do GIS and other geographic information technologies play? What are the current practical problems in China's geological disaster monitoring and prevention? With these questions, we visited Professor Zhou Pinggen, Deputy Chief Engineer of the China Geological Environment Monitoring Institute.
Two Major Triggering Factors, Four Disaster Prevention Systems
China is a country prone to geological disasters. According to the classification by the Ministry of Land and Resources, China's geological disasters are divided into 6 types, including collapses, landslides, and debris flows mainly distributed in mountainous areas, ground subsidence and ground fissures distributed in plain and coastal areas, and ground collapse distributed in mining areas. Natural climate and earthquakes, human engineering activities, etc. can all become triggering factors for geological disasters. Professor Zhou explained: "On one hand, climate change, especially heavy rain or continuous rainfall, is the main factor triggering geological disasters. According to analysis of relevant statistical data in recent years, rainfall-induced sudden geological disasters account for 63% of the total number of geological disasters nationwide. The occurrence of these sudden geological disasters is positively correlated with the intra-annual and inter-annual changes in rainfall. Moreover, climate change-induced ice and snow melting can also trigger geological disasters in plateau areas. At the same time, China is one of the countries with the most frequent and intense continental earthquake activities in the world. Earthquake activities generally show characteristics of high frequency, great intensity, wide distribution range and impact area, and obvious regional differences. Earthquake activities cause rock layer fragmentation, mountain instability, increased loose solid materials, thus triggering landslides, collapses, and debris flows in mountainous areas."
"On the other hand, human engineering activities also intensify the frequency and density of geological disasters. These activities include slope cutting and slope cutting behaviors in mining, road and construction projects, as well as loading of slope soil and rock masses by water conservancy facilities and slope irrigation. With China's economic and social development, various constructions are in full swing, and road traffic facility construction and open-pit mining have become important factors triggering landslides, collapses, and debris flows; underground mining can trigger disasters such as ground collapse, ground subsidence, and ground fissures; the intensification of groundwater extraction and continuous increase in water consumption further exacerbate the occurrence of ground subsidence and ground fissures. Large water conservancy facilities like the Three Gorges Reservoir area must monitor and control water release volume and water level drop amplitude daily to prevent geological disasters such as landslides on both banks caused by large water level drops. For a long time to come, the new district planning and renovation construction in major cities in eastern China, as well as the implementation of the Western Development Strategy in western regions, will see a large number of cities entering the ranks of new construction and expansion. Resource development and infrastructure construction may have important impacts on the ecological environment, thus triggering geological disasters."
Combining natural and human factors that trigger geological disasters, the country has formulated four scientific disaster prevention and mitigation systems: the investigation system, which comprehensively conducts geological disaster investigation and evaluation in prone areas nationwide; the monitoring and early warning system, including joint monitoring and early warning by multiple departments, information sharing, forecast consultation, and early warning linkage; the prevention and control engineering system, including building retaining walls, dams, and drainage channels to prevent debris flows, building anti-slide piles and drainage ditches to prevent landslides, as well as relocation projects for hazard avoidance; and the emergency system, which takes various measures immediately after disasters occur to minimize casualties and economic losses. "The proposal of these four systems is relatively complete and scientific, conducive to the development of various disaster prevention and mitigation works," said Professor Zhou.
Characteristics and Shortcomings of China's Geological Disaster Prevention and Control
Compared to foreign countries, China's geological disaster prevention and control has its own characteristics and shortcomings. Professor Zhou gave examples: "First, there are issues involving standardization in engineering construction. Whether it's the specifications and models of hardware, the data formats of software, or some transmission and communication requirements, interface requirements, etc., all need standardized and refined specifications. In investigation and monitoring, if hardware or software reasons cause the transmitted data analog quantity to deform, it will directly affect further decision-making analysis and cause untimely early warning. For example, many sensors may be installed on a landslide, but only when each sensor directly uploads data with unified standards to the analysis center can data transmission and real-time management proceed smoothly. Currently, the standardization of hardware such as sensors in China's geological disaster monitoring has not been fully formed, resulting in sensors produced by various manufacturers being of different sizes, like the different interfaces of Apple and Nokia mobile phones, causing inconvenience in use; in terms of software, our investigation and collection system data formats have basically achieved nationwide uniformity, but have not been fully realized in monitoring systems and are still being promoted."
"Another problem is that the density of the monitoring network is not high enough. For example, in meteorological rainfall monitoring systems, we usually establish monitoring points at the foot of mountains, but rainfall in mountainous areas varies greatly. Sometimes there is heavy rain on the slope but no rain at the foot, so we can't monitor it. When debris flows start, we haven't discovered them yet, and disaster early warning cannot be achieved. At the same time, both communication technology and GIS technology require certain usage skills. We basically have technical personnel equipped at the national, provincial, and municipal levels, but at the county level, personnel allocation is insufficient, hindering county-level linkage early warning. Therefore, from the perspective of geological disaster monitoring networks, monitoring points need to be increased, and county-level technical personnel configuration needs to be increased to densify monitoring network groups."
"At the same time, in terms of disaster prevention and mitigation methods, relocation and avoidance is the most reliable and safe. In countries like the United States, they usually conduct preliminary investigation and evaluation to identify disaster-prone areas and relocate residents for avoidance. However, there are many practical difficulties in carrying out this work in China. Although China has vast territory, due to its large population, there are still many residents in mountainous areas prone to geological disasters. We are currently organizing relocation work in geological disaster-prone areas, relocating several households to relatively centralized safe areas, but the population threatened by geological disasters in our country reaches over ten million, so complete relocation and avoidance is not practical."
"Besides relocation and avoidance, engineering management is another method, which is most implemented in Japan and Hong Kong. They both belong to areas with little land but many people, where the government invests a lot of funds in engineering management. Landslides are treated with methods such as anchor rods, and debris flows are managed with multi-level retaining dams, completely controlling these disasters invisibly. This management method is effective but requires a lot of funds. Although we are also investing in management, in the vast geological disaster-prone areas, this investment is unrealistic."
"As mentioned earlier, one of the major triggering factors of geological disasters is natural factors. We all know that natural phenomena are very complex, and from this aspect, with current technological levels, it is still impossible to achieve accurate forecasting of natural phenomena in terms of time, space, and scale. A landslide that was originally very stable in spatial judgment may become an unstable area after experiencing rainfall or an earthquake. Originally slightly sliding areas may become stable over time, so whether it's spatial or temporal prediction related to natural phenomena like earthquakes and meteorology, we still cannot fully grasp their patterns and still need long-term research and exploration."
GIS Technology Throughout the Geological Disaster Prevention and Control System
The casualties and economic losses caused by geological disasters continue, and the country's work to strengthen geological disaster prevention and control continues. Modern information technology is also being increasingly applied to geological disaster prevention and control. Among these, the role of GIS and other geographic information technologies is becoming prominent. Professor Zhou stated that for a series of factors triggering geological disasters, GIS is indispensable in the four disaster prevention systems. "From the perspective of overall geological disaster prevention and control, establishing a large platform for real-time data management and updating to support various aspects of geological disaster investigation, monitoring, prevention and control, and emergency response. Whether it's landslides, collapses, or debris flows, these geological disasters are distributed on the earth's surface with location information. Geological disaster management from province, city, county, town to village groups all need to manage their spatial distribution information, all requiring GIS technology."
"Specifically taking the monitoring and early warning link as an example, 'sense-transmit-know-use' can well summarize this process. 'Sense' refers to the initial monitoring data collection; 'transmit' is real-time transmission of monitoring data information through handheld terminals, BeiDou satellites and other communication means; 'know' is equivalent to processing monitoring data, establishing models, and judging the state and trend of disaster bodies through models; 'use' refers to proposing emergency response measures such as geological disaster relocation and transfer through system-assisted decision-making. The entire prediction and early warning process requires the application of remote sensing, remote measurement, navigation positioning, and GIS technologies, and the results analyzed and processed by GIS software are also spatial results that can be used directly. For example, the meteorological early warning information broadcast on TV now is all calculated on GIS platforms. The rainfall monitoring data from meteorological stations and our geological disaster rainfall monitoring data are combined, analyzed and processed with GIS to obtain results."
"In monitoring and early warning, on one hand, there are monitoring methods using instruments and communication technology, and on the other hand, there is the mass monitoring and prevention system where residents in disaster-prone areas are taught methods to judge disaster occurrence and evacuate in time before disasters strike. In this system, ordinary people can also collect data through mobile phones and other handheld terminals, transmitting information to monitoring and early warning centers at any time. Relevant departments can make timely judgments on geological disaster situations based on feedback information from everyone."
"For earthquakes, although we cannot forecast them and cannot issue early warnings, we can simulate the state after an earthquake occurs, what magnitude would cause what range of impact, what geological disasters would be triggered in which areas, and what further impacts would occur when rainfall happens simultaneously, etc., so that we can quickly respond and make decisions after an earthquake occurs. For example, in the Lushan earthquake, after the earthquake occurred, the research team from Chengdu University of Technology quickly judged the dangerous areas of collapses and landslides based on previously established corresponding models, guiding the direction of disaster relief work."
"It can be said that without GIS and other technologies, using some primitive methods, disaster monitoring can still be done, and mass monitoring and prevention can still continue, but the effect will definitely be greatly reduced. For content like meteorological early warning and dynamic early warning, without GIS they cannot be done in a timely manner. The current operation of the entire geological disaster prevention system is carried out under the support of GIS. Including comprehensive decision-making systems, unified scheduling of information and elements from all aspects to improve decision accuracy and efficiency. So what is the role of informatization means? What is the role of geographic information technology? It is to realize things that could not be achieved before, and to release things that could not be published dynamically and in real time. It is a very important tool that can bring qualitative changes to geological disaster prevention and control."
BeiDou Application Grasping Both Communication and Positioning
The BeiDou system began providing navigation and other services to the Asia-Pacific region at the end of 2012, and as early as 2007 when there were only three satellites, its role in geological disaster monitoring began to emerge. Professor Zhou gave us a detailed introduction: "At that time, in mountainous area monitoring systems, due to often poor mobile phone signals and limited data transmission, we began considering using the communication function of the BeiDou system. Because the BeiDou system was quite expensive at the time, we initially chose only one landslide and used only 2 BeiDou devices for data transmission, and developed a system using solar energy to power the BeiDou devices, ensuring uninterrupted real-time data transmission and solving the communication problem. Later, with support from the National Development and Reform Commission's high-tech industrialization application project, the BeiDou-based transmission system was promoted to large-scale application, and the Three Gorges Reservoir area, Sichuan Ya'an, Yunnan Ailao Mountain, and Zhejiang and Jiangxi were selected as pilot areas. Today, the automatic monitoring systems in these areas are still operating. Although with the development of communication technology, mobile phone signals have gradually strengthened, transmission capacity has increased, and costs are relatively cheap, BeiDou also has its own advantages. In the second generation of BeiDou, the channel bandwidth will be further increased, able to transmit larger amounts of data, including video data, and we will continue to use this data transmission method for monitoring and early warning services."
"In emergency rescue, BeiDou's communication function is also very important. In the 2008 Wenchuan earthquake, when the entire communication system was paralyzed, rescue personnel entered the epicenter on foot and used BeiDou handheld devices to send disaster information via SMS, allowing people outside to grasp the specific situation for deployment and carry out subsequent rescue work."
"While providing communication services, BeiDou's navigation and positioning functions are also reflected in geological disaster monitoring and emergency work. For example, in ground subsidence monitoring systems, using position accuracy data from several satellites over a period of time, through certain algorithms, precise positioning can be achieved with accuracy reaching 3-5mm level; in landslide deformation monitoring, real-time monitoring of millimeter-level changes can improve the efficiency and accuracy of monitoring and early warning work. Some geological disasters occur very quickly, requiring greater measurement accuracy. BeiDou system's current network of 16 satellites can already achieve high-precision positioning and will play a greater role in geological disaster monitoring, early warning, and emergency response in the future. At the same time, the positioning function can also obtain the specific location of field staff, providing security guarantees for their field work."
"From investigation and monitoring to emergency response, whether it's communication functions or positioning functions, like today's GPS vehicle navigation and positioning, BeiDou system's application scope and prospects in the geological disaster prevention system will be unlimited."
Smarter Geological Disaster Prevention and Control System
Future informatization applications integrating Internet of Things and cloud computing are called "smart cities," "smart transportation," etc. in many industries. The Ministry of Land and Resources has also proposed the construction of "smart land and resources." When talking about future geological disaster prevention and control system construction, Professor Zhou said confidently: "Our future goal is to build a complete real-time monitoring system. The system has fixed ends, which are numerous monitoring points, and mobile ends, which are the broad masses in mass monitoring and prevention. All dynamic information converges to the monitoring system center for analysis and processing; at the same time, improving spatial recognition and model prediction capabilities, improving investigation accuracy. Linking investigation, monitoring and early warning with emergency response, rapid investigation and rapid monitoring, field experts can simultaneously obtain various monitoring data and model information with backend experts, interact in real time, and make decisions together."
"Another very important aspect is achieving information sharing. This sharing is not only sharing among various fields of geological disaster prevention and control, but also information sharing among various departments. Including meteorological data from meteorological departments, geological survey data from geological survey departments, traffic data from transportation departments, etc. What one department produces can be used by several departments, optimizing allocation, saving resources, and improving efficiency."
"Launching more remote sensing satellites, making full use of satellite remote sensing data, BeiDou applications, GIS data collection, analysis, and decision-making. The development of 3S technology will definitely have a greater impact on the entire disaster reduction and prevention work."
