Neely Wesley R, Borsa Adrian A, Burney Jennifer A, Levy Morgan C, Silverii Francesca, Sneed Michelle
Scripps Institution of Oceanography University of California San Diego La Jolla CA USA.
School of Global Policy and Strategy University of California San Diego La Jolla CA USA.
Water Resour Res. 2021 Apr;57(4):e2020WR028451. doi: 10.1029/2020WR028451. Epub 2021 Apr 7.
Surface deformation in California's Central Valley (CV) has long been linked to changes in groundwater storage. Recent advances in remote sensing have enabled the mapping of CV deformation and associated changes in groundwater resources at increasingly higher spatiotemporal resolution. Here, we use interferometric synthetic aperture radar (InSAR) from the Sentinel-1 missions, augmented by continuous Global Positioning System (cGPS) positioning, to characterize the surface deformation of the San Joaquin Valley (SJV, southern two-thirds of the CV) for consecutive dry (2016) and wet (2017) water years. We separate trends and seasonal oscillations in deformation time series and interpret them in the context of surface and groundwater hydrology. We find that subsidence rates in 2016 (mean -42.0 mm/yr; peak -345 mm/yr) are twice that in 2017 (mean -20.4 mm/yr; peak -177 mm/yr), consistent with increased groundwater pumping in 2016 to offset the loss of surface-water deliveries. Locations of greatest subsidence migrated outwards from the valley axis in the wetter 2017 water year, possibly reflecting a surplus of surface-water supplies in the lowest portions of the SJV. Patterns in the amplitude of seasonal deformation and the timing of peak seasonal uplift reveal entry points and potential pathways for groundwater recharge into the SJV and subsequent groundwater flow within the aquifer. This study provides novel insight into the SJV aquifer system that can be used to constrain groundwater flow and subsidence models, which has relevance to groundwater management in the context of California's 2014 Sustainable Groundwater Management Act (SGMA).
加利福尼亚中央谷地（CV）的地表变形长期以来一直与地下蓄水层的变化相关。遥感技术的最新进展使得能够以越来越高的时空分辨率绘制CV变形图以及相关的地下水资源变化图。在此，我们使用哨兵 - 1任务的干涉合成孔径雷达（InSAR），并辅以连续全球定位系统（cGPS）定位，来描述圣华金谷（SJV，CV的南三分之二）在连续干旱（2016年）和湿润（2017年）水年的地表变形情况。我们分离了变形时间序列中的趋势和季节性振荡，并结合地表水和地下水文情况对其进行解释。我们发现，2016年的沉降速率（平均 -42.0毫米/年；峰值 -345毫米/年）是2017年（平均 -20.4毫米/年；峰值 -177毫米/年）的两倍，这与2016年增加地下水抽取以抵消地表水供应减少的情况一致。在较湿润的2017水年，沉降最大的区域从谷底轴线向外迁移，这可能反映了圣华金谷最低区域地表水供应过剩。季节性变形幅度和季节性抬升峰值时间的模式揭示了地下水补给进入圣华金谷以及随后在含水层中流动的入口点和潜在路径。本研究为圣华金谷含水层系统提供了新的见解，可用于约束地下水流和沉降模型，这与加利福尼亚州2014年《可持续地下水管理法案》（SGMA）背景下的地下水管理相关。
