基于InSAR的北京平原区地面沉降与地下水位演化关联特征迭代奇异谱分析

Iterative Singular Spectral Analysis of the Correlation between Land Subsidence and Groundwater Level Evolution in Beijing Plain Based on InSAR

北京平原区是地面沉降发展严重的区域之一,分析其地面沉降的时空演化规律可为城市地面沉降有效防控提供数据支撑。该文利用PS-InSAR方法获取地面沉降信息,并用水准监测数据验证其精度,然后基于奇异谱分析和频谱检验提出迭代奇异谱分析(Iterative Singular Spectral Analysis,ISSA)方法,并基于该方法将地面沉降的长时序数据分解为主趋势、周期特征,得到研究区地面沉降和地下水位的时序演化特征:①研究区地面沉降的主趋势特征表现为2011—2016年沉降持续、沉降减缓和再度发展3个阶段,2017—2020年沉降持续发展,但总体趋势较稳定。②研究区地面沉降季节性差异明显,且2011—2020年夏季地面沉降比冬季严重。③地下水超采是北京平原区地面沉降的主因,在严重沉降区和较严重沉降区,第二、三承压含水层的水位变化与地面沉降呈强正相关性。

The Beijing Plain is currently experiencing significant land subsidence,which requires a thorough analysis of its spatial and temporal evolution mechanism to predict future trends.This is essential in ensuring the safety of the city while effectively preventing and controlling land subsidence.This paper utilizes the PS-InSAR method to collect land subsidence data,which is validated for accuracy through leveling data.Moreover,based on the singular spectrum analysis and frequency-spectrum checking,the iterative singular spectral analysis(ISSA)method is proposed to decompose the long time series data of land subsidence into primary trends and periodic characteristics,offering insights into the time series evolution of land subsidence and groundwater level in the study area.It is found as follows.①The land subsidence is characterized by three main trend characteristics of continuous subsidence,subsidence mitigation,and re-subsidence from 2011 to 2016,and that subsidence continues to develop from 2017 to 2020,but the overall trend is more stable.②The periodic characteristics of land subsidence,which is characterized by the obvious seasonal difference of land subsidence in the study area,and the land subsidence in summer is more serious than that in winter from 2011 to 2020.③The primary cause of land subsidence in the Beijing Plain is changes in groundwater level,and that the groundwater level changes of the second and third confined aquifers show a strong positive correlation with land subsidence in the severe and more severe subsidence areas.