At present, 3D GIS is mainly used in many fields at home and abroad, such as land and urban planning, cadastral survey, urban management, smart city construction, emergency system, oil and gas pipeline inspection, river protection and so on. The application in geological disasters is also expanding. Now its application in geological disasters is mainly reflected in these aspects:
(1)Geological hazard evaluation and management.
(2)Risk zoning evaluation of geological hazards.
(3)Integrated application of 3D GIS and expert system.
1.Application of 3D GIS in earthquake
The application of 3D GIS in earthquake is manifested in earthquake analysis, prediction, prediction, earthquake resistance, disaster reduction, disaster relief and post disaster evaluation. It is mainly reflected in forecasting, disaster assessment and disaster reduction.
● Earthquake prediction
Earthquake is one of the most serious natural disasters to economic development and social stability. So far, earthquake prediction is still a worldwide problem.
At present, the main basis for earthquake prediction is still various earthquake precursors. Experts make earthquake prediction according to various phenomena and experience. The computer can automatically collect data and automatically distinguish anomalies, and then carry out earthquake prediction according to the rich information provided by geographic information system, which can make reasoning and intelligent decision more objectively and systematically. Such as earthquake prediction intelligent decision support system.
● Loss assessment of earthquake disaster
The first is the post earthquake loss assessment. Based on the system platform constructed by 3D GIS, the affected area and the number of affected houses can be calculated according to the tilt photography model, and the loss assessment can be made based on the analysis of building structure data.
The second is the loss estimation before the earthquake. Although no one wants the earthquake to happen, the loss assessment can be done before the earthquake, which is convenient for the improvement of urban planning and architectural design, and finally reduce the earthquake loss.
● Disaster reduction after earthquake
Quick decision-making after earthquake is a very important way to reduce earthquake loss. Spatial analysis such as the shortest path provided by 3D GIS is used to provide objective and direct opinions for leaders' decision-making. The emergency decision-making made by using 3D GIS is mainly reflected in the following aspects: disaster relief plan; Personnel shock evacuation; Hazard warning and preventive measures at each dangerous goods storage point; Earthquake fire auxiliary decision-making and so on. It can be said that within a few hours after the earthquake, these aspects are closely related to people's life safety.
2.Application of 3D GIS in collapse and landslide
The application of 3D GIS in collapse and landslide is mainly reflected in the risk assessment before disaster.
General geological disasters can be divided into pre disaster incubation stage - disaster activity stage - post disaster recovery stage. For sudden geological disasters, such as collapse and landslide, the disaster activity stage is often very short. The assessment of such disasters is mainly pre disaster risk.
Assessment and post disaster loss assessment, from the perspective of disaster prevention and reduction, in order to take the initiative and prevent the accident, pre disaster risk assessment is particularly important, which is the focus of our work and research.
● Pre disaster risk assessment of collapse and landslide
The introduction of 3D GIS into collapse and landslide hazard risk assessment mainly takes into account the spatial data management ability and its powerful spatial data analysis ability of 3D GIS. It is used as an analysis tool for geological hazard risk assessment to accelerate the process of collapse and landslide hazard assessment and improve the accuracy of hazard assessment. At the same time, due to the unique spatial analysis function and super data analysis ability of 3D GIS, some evaluation methods that can only be completed by 3D GIS are derived in the process of collapse and landslide geological hazard risk evaluation. Moreover, this risk evaluation method that makes full use of the function of 3D GIS is still emerging. The purpose of collapse and landslide geological hazard risk assessment supported by 3D GIS is to distinguish different risk grade areas and reflect them through risk mapping.
For geological hazard risk assessment using 3D GIS, it is necessary to make full use of the spatial superposition analysis function of 3D GIS to represent each factor affecting collapse and landslide with a thematic map. In vector based spatial overlay analysis, multiple thematic layers overlay each other to produce new polygons with the attributes of the original multiple thematic maps; In grid based spatial overlay analysis, four corresponding operations or function operations are performed between the grids corresponding to each layer to obtain a new grid thematic map, which is the result of each factor layer operation.The collapse and landslide risk assessment method based on Three-dimensional GIS is essentially a function cloud superposition operation for the input evaluation factor layers, and the result of superposition operation is the result of risk assessment. In essence, this risk assessment can be expressed as a function of multiple layers.
3.Application of 3D GIS in debris flow
The application of 3D GIS in debris flow is mainly in debris flow risk assessment and debris flow early warning. There are more than 10000 disastrous debris flow gullies and tens of thousands of landslides in China, which seriously affect the social and economic development of the vast mountainous areas. In order to reduce the impact of landslide and debris flow disasters, it is necessary to formulate an overall strategy of disaster management. Such a strategy involves three aspects: disaster prevention, disaster early warning and disaster reduction. However, in terms of debris flow, RS and 3D GIS are generally applied to debris flow, so as to have a good effect.
4.Application of 3D GIS in land subsidence
The application of 3D GIS in land subsidence is mainly reflected in the prediction of land subsidence. Land subsidence has become an important factor restricting urban development. Serious land subsidence can cause disasters such as poor surface and underground drainage and subsidence of building foundation, which will do great harm to human engineering activities and production environment. 3D GIS provides a new way to understand and understand geoscience. Its powerful spatial analysis function and database management ability provide an effective way for the research of urban land subsidence.Three dimensional GIS can predict land subsidence from the perspective of space and time. Using 3D GIS technology as a platform, combined with land subsidence simulation and prediction methods, and making full use of GPS and remote sensing data, a settlement dynamic monitoring, prediction and early warning system is established, and 3D GIS is used to realize the visualization of land subsidence.
5.Application of 3D GIS in soil and water loss
The application of 3D GIS in soil and water loss is mainly reflected in the risk assessment of soil and water loss. As an interdisciplinary science, soil and water loss is a very complex geoscience problem, which involves many influencing factors and is closely related to spatial data. The spatial analysis ability, modeling ability and spatial data management ability of 3D GIS provide technology for the analysis of soil and water loss.
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