Advanced techniques of multi-temporal InSAR (MT-InSAR) represent a valuable tool in ground subsidence studies allowing remote investigation of the behavior of mass movements in long time intervals by using large datasets of SAR images covering the same area and acquired at different epochs. Beijing is susceptible to subsidence, producing undesirable environmental impacts and affecting dense population. Excessive groundwater withdrawal is thought to be the primary cause of land subsidence, and rapid urbanization and economic development, mass construction of skyscrapers, highways and underground engineering facilities (e.g., subway) are also contributing factors. In this paper, a spatial–temporal analysis of the land subsidence in Beijing was performed using one of the MT-InSAR techniques, referred to as Small Baseline Subset (SBAS). This technique allows monitoring the temporal evolution of a deformation phenomenon, via the generation of mean deformation velocity maps and displacement time series from a data set of acquired SAR images. 52 C-band ENVISAT ASAR images acquired from June 2003 to August 2010 were used to produce a linear deformation rate map and to derive time series of ground deformation. The results show that there are three large subsidence funnels within this study area, which separately located in Balizhuang-Dajiaoting in Chaoyang district, Wangjing-Laiguangying Chaoyang district, Gaoliying Shunyi district. The maximum settlement center is Wangsiying-Tongzhou along the Beijing express; the subsidence velocity exceeds 110 mm/y in the LOS direction. In particular, we compared the achieved results with leveling measurements that are assumed as reference. The estimated long-term subsidence results obtained by SBAS approach agree well with the development of the over-exploitation of ground water, indicating that SBAS techniques is adequate for the retrieval of land subsidence in Beijing from multi-temporal SAR data.

The effects of ground deformation pose a significant geo-hazard to the environment and infrastructure in Wuhan, the most populous city in Central China, in the eastern Jianghan Plain at the intersection of the Yangtze and Han rivers. Prior to this study, however, rates and patterns of region-wide ground deformation in Wuhan were little known. Here we employ multi-temporal SAR interferometry to detect and characterize spatiotemporal variations of ground deformation in major metropolitan areas in Wuhan. A total of twelve TerraSAR-X images acquired during 2009–2010 are used in the InSAR time series analysis. InSAR-derived results are validated by levelling survey measurements and reveal a distinct subsidence pattern within six zones in major commercial and industrial areas, with a maximum subsidence rate up to −67.3 mm/year. A comparison analysis between subsiding patterns and urban developments as well as geological conditions suggests that land subsidence in Wuhan is mainly attributed to anthropogenic activities, natural compaction of soft soil, and karst dissolution of subsurface carbonate rocks. However, anthropogenic activities related to intensive municipal construction and industrial production have more significant impacts on the measured subsidence than natural factors. Moreover, remarkable signals of secular land uplift are found along both banks of the Yangtze River, especially along the southern bank, with deformation rates ranging mostly from +5 mm/year to +17.5 mm/year. A strong temporal correlation is highlighted between the detected displacement evolutions and the water level records of the Yangtze River, inferring that this previously unknown deformation phenomenon is likely related to seasonal fluctuations in water levels of the Yangtze River.

Evaluating the impacts of climatic changes and morphometric features on glacier mass balance is crucial to providing insight into glacier changes and their effects on regional water resources and ecosystems. Here, we presented an evaluation of morphometric effects on the glacier mass balances of the Puruogangri ice field (PIF) on the Tibetan Plateau. A clear spatial variability of glacier mass balances, ranging from −0.035 to +0.019 m·w.e.·year⁻¹, was estimated by comparing the TanDEM-X DEM (2012) with the SRTM-X DEM (2000). In general, the observed glacier mass changes were consistent with our fieldwork investigations. Furthermore, by applying the method of linear regression analysis, we found that the mass changes of individual glaciers on the PIF were mainly dominated by the mean altitude (R = 0.84, p < 0.001), however, they were statistically independent of glacier size, aspect, and surface velocity. At a local scale (grid size of 10 × 10 pixels), apart from the factor of altitude, surface velocity was correlated with glacier mass change.

The headwaters of many Asian rivers are at mountain glaciers of the Tibetan Plateau. Glacier melt-water is a non-negligible contributor of river runoff, especially for a drought year. However, the observation of mass glacier changes was scarce in recent years. Here, we estimated the recent glacier mass change of the Geladandong mountain, by differencing the digital elevation models (DEMs) produced from ZiYuan-3 images and TanDEM-X data. Moreover, we compared the SRTM-C DEM with TanDEM-X DEMs to retrieve glacier mass balances since 2000. The annual mass loss rates of −0.11 ± 0.03 and −0.47 ± 0.09 m w.e. yr⁻¹ were derived in 2000–2012 and 2012−2018, respectively. This result revealed an accelerating rate of negative glacier mass changes during recent years, which is mainly caused by the significant increase of mass loss over non-surge glaciers, rather than surge-type glaciers, which held a slight increase of mass loss. In addition, we found a pronounced discrepancy of glacier mass change between non-surge and surge-type glaciers during 2012−2018, and suggested that this difference may be caused by the heterogeneous responses of surge-type glaciers to climate variations, because of the different timing and type of surge events.

The Tibetan Plateau (TP) has the largest number of high-altitude glaciers on Earth. As a source of major rivers in Asia, this region provides fresh water to more than one billion people. Any terrestrial water storage (TWS) changes there have major societal effects in large parts of the continent. Due to the recent acceleration in global warming, part of the water environment in TP has become drastically unbalanced, with an increased risk of water disasters. We quantified secular and monthly glacier-mass-balance and TWS changes in water basins from April 2002 to December 2021 through the Gravity Recovery and Climate Experiment and its Follow-on satellite mission (GRACE/GRACE-FO). Adequate data postprocessing with destriping filters and gap filling and two regularization methods implemented in the spectral and space domain were applied. The largest glacier-mass losses were found in the Nyainqentanglha Mountains and Eastern Himalayas, with rates of −4.92 ± 1.38 Gt a⁻¹ and −4.34 ± 1.48 Gt a⁻¹, respectively. The Tien Shan region showed strong losses in its eastern and central parts. Furthermore, we found small glacier-mass increases in the Karakoram and West Kunlun. Most of the glacier mass change can be explained by snowfall changes and, in some areas, by summer rainfall created by the Indian monsoon. Major water basins in the north and south of the TP exhibited partly significant negative TWS changes. In turn, the endorheic region and the Qaidam basin in the TP, as well as the near Three Rivers source region, showed distinctly positive TWS signals related to net precipitation increase. However, the Salween River source region and the Yarlung Zangbo River basin showed decreasing trends. We suggest that our new and improved TWS-change results can be used for the maintenance of water resources and the prevention of water disasters not only in the TP, but also in surrounding Asian countries. They may also help in global change studies.