Hwang Cheinway, Yang Yuande, Kao Ricky, Han Jiancheng, Shum C K, Galloway Devin L, Sneed Michelle, Hung Wei-Chia, Cheng Yung-Sheng, Li Fei
Department of Civil Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan.
Chinese Antarctic Center of Surveying and Mapping, Wuhan University, 129 Luoyu Road, Wuhan 430079, China.
Sci Rep. 2016 Jun 21;6:28160. doi: 10.1038/srep28160.
Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal subsidence monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land subsidence in cropland areas. Subsidence rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-2 during 1992-2015 show time-varying trends with respect to displacement over time in California's San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, subsidence rates reach 18 cm yr(-1) with a cumulative subsidence of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum subsidence rate in central Taiwan is 8 cm yr(-1). Radar altimetry also reveals time-varying subsidence in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm yr(-1) and cumulative subsidence as much as 155 cm.
雷达测高术的当代应用包括海平面上升、海洋环流、海洋重力以及冰盖高程变化。与广泛用于绘制地表形变的合成孔径雷达干涉测量（InSAR）和全球导航卫星系统（GNSS）不同，测高术既不依赖于时间上高度相关的地面特征，也不受可用空间覆盖范围的限制，并且能够提供长期的地面沉降监测能力。在此，我们使用数据跨度约为23年的多任务雷达测高术来量化农田地区的地面沉降。1992年至2015年期间，托佩克斯/海神号（TOPEX/POSEIDON）、杰森-1号（JASON-1）、环境卫星（ENVISAT）和杰森-2号（JASON-2）的沉降速率显示出与加利福尼亚州圣华金河谷和台湾中部随时间的位移相关的时变趋势，这可能与土地利用变化、气候条件（干旱）以及影响地下水使用的监管措施有关。在加利福尼亚州汉福德附近，沉降速率达到每年18厘米，累计沉降量为206厘米，这可能会对规划中的加利福尼亚高速铁路的运营产生不利影响。台湾中部地区最大沉降速率为每年8厘米。雷达测高术还揭示了华北平原的时变沉降情况，这与重力恢复与气候实验（GRACE）卫星检测到的地下水位下降和现有水利设施情况一致，沉降速率达到每年20厘米，累计沉降量高达155厘米。
