太原盆地地面沉降时序InSAR监测与季节性变形小波分析
Published in June, 2023
Groundwater overexploitation has been lasted for decades in Taiyuan Basin, causing the regional groundwater level to decline, which has been resulting in serious land subsidence. The temporal and spatial evolution of land subsidence has a strong correlation with the dynamic evolution of groundwater level. In this paper, we processed Sentinel-1 satellite data from 2015 to 2020 by SBAS-InSAR algorithm to investigate the surface deformation in Taiyuan Basin. A seasonal deformation model was used to separate the linear trend and the seasonal periodic signal in the deformation time series. Based on the wavelet analysis method, the periodic evolution characteristics of surface subsidence and groundwater level, and their time-lag relationships were quantitatively analyzed. We found that: (1) land subsidence mainly occurred in the central part of Taiyuan Basin (Xiaodian—Qingxu—Jiaocheng—Qixian—Taigu area, with a maximum rate up to -70.0 mm·a-1), in the western part (Qingxu—Jiaocheng area, with a maximum rate up to -63.4 mm·a-1) and in the southern part (Xiaoyi—Jiexiu area, with a maximum rate up to -72.2 mm·a-1); (2) due to the implementation of a series of water management practices such as closing wells and the Wanjiazhai Water Diversion project, groundwater level in Taiyuan City has been rising, the land has reversed from subsidence to uplift, with an overall uplift rate about 9 mm·a-1; (3) the surface deformation in the central part of Taiyuan Basin (Qingxu—Qixian—Taigu area) presented an obvious “subsidence-rebound” periodic variation following with the seasonal “drainage-recharge” behavior of the groundwater level variations; (4) the time-lag relationship between seasonal surface deformation and groundwater level change was not significant (only 22 days), indicating that low-permeability clay units in this region have little influence on delaying the compaction of aquifer systems. The results of our paper can provide a scientific support for the formulation of land subsidence prevention and control and sustainable water resource exploitation and utilization planning in the Taiyuan Basin.
太原盆地长期过量超采地下水，区域地下水位持续下降，导致了严重的地面沉降。地面沉降的时空演变特征与地下水位的动态演化具有很强的相关性。本文使用2015—2020年的Sentinel-1卫星数据进行时序SBAS-InSAR处理，获取了太原盆地地表形变速率和时间序列，并采用季节性形变模型分离形变时间序列中的线性趋势和季节性周期信号。基于小波变换分析方法，定量分析了地表沉降与地下水位的周期演化特征以及两者之间的时间滞后关系。研究发现：(1)地面沉降主要发生在太原盆地中部(小店—清徐—交城—祁县—太谷一带，速率达到-70.0 mm/yr)、西侧边山(清徐—交城一带，速率达到-63.4 mm/yr)和南部(孝义—介休一带，速率达到-72.2 mm/yr)。(2)由于地下水压采和“引黄入晋”引水工程等一系列水资源管理措施的实施，太原市区地下水位回升，地面由沉降转变为抬升，整体抬升速率约9 mm/yr。(3)太原盆地中部(清徐—祁县—太谷一带)地表形变随着地下水位的季节性“开采—补给”作用而呈现出明显的“沉降—反弹”周期变化特征，年周期形变振幅达到26.2 mm。(4)盆地内季节性地表形变和地下水位变化之间的时间滞后关系不明显(仅为22天)，说明该区域低渗透粘土对延缓含水层系统压实的影响有限。本文结果可为太原盆地地面沉降防控和水资源可持续开采利用方案的制定提供科学依据。