Research On Wide-area InSAR Geological Hazard Identification And Evaluation Algorithm

China is one of the countries where geological disasters occur frequently.In recent years,direct economic losses due to geological hazards have accounted for more than 20% of the total economic losses due to natural disasters,posing a serious threat to human casualties and property damage,and putting enormous pressure on the safety and security of people’s lives and the sustainable development of society.Interferometric Synthetic Aperture Radar(In SAR)technology has been widely used in wide-area geohazard monitoring due to its advantages of wide monitoring range,data processing automation and high accuracy.Therefore,based on the current research status of In SAR technology in long time series processing technology and hazard identification,this paper mainly proposes the following research contents:(1)To address the problems of low computational efficiency and high redundancy in the existing long time series In SAR monitoring and the difficulty of operationalization of the existing methods,a joint intercorrelation time series leveling method based on the multi-period time series In SAR monitoring results is proposed.In this method,the corresponding functional and stochastic models of the levelling method are proposed based on the multi-period monitoring results already obtained in the operational application,and the data processing process and the specific levelling procedure are established,and the levelling results obtained include deformation rates and deformation sequence values.The method is applied to Zhuhai,Guangdong Province,a coastal region with large-scale deformation,and the deformation rate difference is less than 1mm/yr and the overall cumulative deformation accuracy is higher than 3mm compared with the traditional time-series In SAR overall processing,which meets the accuracy requirements in the overall results and local key point fitting.The method can reduce repetitive operations compared with the traditional time-series In SAR method,and has achieved the overall processing effect;(2)In response to the difficulty of automatically locating deformation areas and assessing ground motion status in wide-area In SAR,an improved method for identifying potentially unstable or hazardous areas is proposed based on the distribution pattern of spatio-temporal features of time-series In SAR monitoring results.The method focuses on extracting spatial rate gradations and temporal evolution trends,which are combined to assess deformation zone instability and its refined boundaries.The method is applied to the identification of potential ground hazard areas in mountainous areas(Lajia Town,Qinghai Province)and urban areas(Dongguan City,Guangdong Province).A total of 23 potential landslides were identified in Lajia Town,Qinghai Province,and a total of 221 potential geological hazard areas were identified in Dongguan City,Guangdong Province.The experimental results show that the method is effective in accelerating the efficiency of deformation zone identification and enhancing the ability to assess geological hazards over a wide area;(3)The Pearl River Delta(PRD)is the largest economic region in China and is also the most widely distributed region in terms of geological hazards.In this paper,a total of 630 potential geological hazard areas were identified in the study area by applying geological hazard identification algorithms with appropriate thresholds.The research analysis shows that the subsidence areas in the border and surrounding coastal areas of Zhuhai,Jiangmen and Zhongshan are the largest and the most significantly deformed.The cause of deformation in the PRD region is mainly due to the geological structure of the soft soil layer as an endogenous factor and the dramatic increase in engineering and human activities as an exogenous factor,causing the compressive soft soil layer to compact and cause surface subsidence.