Land subsidence and rebound in the Taiyuan basin, northern China, in the context of inter-basin water transfer and groundwater management
Published in November 17, 2021
The freshwater scarcity and sustainability of overexploited aquifers have been recognized as a big threat to global water security for human development. Consequently, much research has focused in the past on negative consequences of groundwater abstraction, but somewhat less has been documented about the impacts of adequate management practices to address water shortages. Here, using an integrated analysis of InSAR displacement data, groundwater, and geophysical modeling we show how combined management provisions and inter-basin water transfer project has affected the aquifer system in Taiyuan basin in North China. Following groundwater recovery, the alleviation of land subsidence was found with rates being reduced by up to ~70% in the period 2017–2020 with respect to the period 2007–2010. The increase in pore pressure caused by rising groundwater in Taiyuan city, north of the basin, turned four subsidence centers with rates exceeding 110 mm/yr in the 1980 to uplift centers with rates up to +25 mm/yr between 2017 and 2020. A simple linear elastic model for homogenous subsurface properties can explain InSAR-measured surface displacements well. In the central basin, we found a significant seasonal displacement with annual amplitude up to 43 mm (negative peak in autumn and positive peak in spring) related to the groundwater recharge and discharge due to agricultural pumping irrigation. Using cross-wavelet method, we showed a relatively short time lags (less than one month) between surface deformation and water level changes in the central basin, indicating the low-permeability clayey units have a limited influence in delaying the compaction of aquifer system. Quantifying the effects of adequate groundwater management measures and large-scale engineering approaches like inter-basin water transfer to recharge pumped aquifers provide insight for local governments and decision-makers to properly evaluate the impacts of their policy in recovering the sustainability and efficiency of aquifers in water-deficient basins.
地下水的过度开采和水资源可持续性问题已被认定为全球水安全面临的重大威胁，直接影响到人类发展。因此，过去的研究大多集中在地下水开采带来的负面影响上，但关于应对水短缺的有效管理措施影响的文献相对较少。在本研究中，我们通过综合分析 InSAR 位移数据、地下水监测数据和地球物理建模，展示了综合管理措施与跨流域调水工程如何影响北方太原盆地的含水层系统。随着地下水恢复，土地沉降得到了缓解，2017-2020 年期间沉降速率较 2007-2010 年期间降低了约 70%。太原市（位于盆地北部）地下水位上升引起的孔隙压力增加，使得四个沉降中心（沉降速率超过 110 mm/yr）转变为上升中心，2017 至 2020 年期间，沉降速率由负值变为正值，达到了+25 mm/yr。使用简单的线性弹性模型模拟均匀地下层特性，能够很好地解释 InSAR 测量的地表位移。在盆地中央，我们发现存在显著的季节性位移，年振幅高达 43 mm（秋季为负峰值，春季为正峰值），这与农业灌溉抽水引起的地下水补给和排放相关。通过小波交叉分析，我们展示了表面变形与水位变化之间存在较短的时间滞后（不到一个月），这表明低渗透性粘土层对含水层压实的延迟影响有限。量化地下水管理措施和大规模工程方案（如跨流域调水）对抽水含水层的补给作用，为地方政府和决策者提供了有价值的见解，帮助他们正确评估政策对恢复含水层可持续性和效率的影响，尤其是在水资源匮乏的盆地地区。