Earth and Rock-Filled Dam Monitoring by High-Resolution X-Band Interferometry: Gongming Dam Case Study

Abstract

Middle-sized earth- and rock-filled dams with clay cores continue to settle by approximately 0.5–1.5% of their height for approximately 1–3 years after their construction phase. This paper investigates the use of high-resolution spaceborne Synthetic aperture Radar (SAR) interferometry to monitor this settlement process, with the case of the Gongming dam in China. The varieties of slope foreshortening and stretching in the radar coordinates are attributed to the radar’s local incidence angle and the dam’s slope heading, which are analysed in detail. Focusing on the embankment slope settlement analysis, the equations for calculating foreshortening and the line-of-sight deformation decomposition are derived in detail for the adjustment and data fusing. The scattering characteristics of different materials on the dam surface are analysed, including the grass slope, concrete slope, top road (crest), top wall, step, and ditch. According to the analysis of the precipitation data from a local meteorological station, the coherence losses on the slopes are mainly caused by surface moisture. Both the TerraSAR-X Spotlight (TSX-SL) data and the COSMO-SkyMed Strip Mode (CSK-SM) data are analysed by the stacking method to assess the slopes’ deformations. The TSX-SL data results show the highest rate of settlement as 2 cm/yr on the top of the dam slope, consistent with the clay core shrinking process. The CSK-SM data show a similar trend in the lower part of the dam slope but underestimate the deformation in the upper part of the slope.

Study on LOS to Vertical Deformation Conversion Model on Embankment Slopes Using Multi-Satellite SAR Interferometry

“…Taking into account the compression factor of dam planes, Al-Husseinawi et al [7] presented the maximum detectable gradient of deformation, revealing the difficulty in monitoring dam deformation induced by a nearby earthquake using Sentinel-1 data. Li et al [16] analyzed the difference between COSMOS and TerraSAR-X data in terms of deformation assessment of the earth-rock dams in Gongming Reservoir. The actual measurement results show that the low-resolution data reduce the reliability of the deformation results of PS points [16].…”

“…Li et al [16] analyzed the difference between COSMOS and TerraSAR-X data in terms of deformation assessment of the earth-rock dams in Gongming Reservoir. The actual measurement results show that the low-resolution data reduce the reliability of the deformation results of PS points [16]. The above literature is concerned with exemplary studies on the scale effect of multi-resolution SAR images for dam slope deformation monitoring.…”

“…Eriksen et al [19] studied several landslide areas in Norway by PS technology using ascending and descending data, and the acquired 2D deformation of landslide slopes helped the division of landslide sub-blocks and the analysis of movement mechanism [19]. Li et al analyzed the LOS deformation difference due to the various local incident angles from different parts of the dam slope and proposed a LOS to vertical deformation correction model to correct the time series deformation of the Gongming Reservoir in Shenzhen, China [16].…”

Using TerraSAR X-Band and Sentinel-1 C-Band SAR Interferometry for Deformation Along Beijing-Tianjin Intercity Railway Analysis

“…The deformation obtained by TSX SL with 1 meter spatial resolution and 11 days revisit cycle provides a refined target monitoring capability [9] [10]. The TSX SM with 3 meters spatial resolution data also shows impressive details of urban deformation monitoring [11][12] [13]. Sentinel-1A, as the first environmental monitoring satellite of the European Space Agency's Copernicus program, was launched on 3 April 2014, which can provide the Interferometric Wide mode and greatly increase the image width for large-area observations.…”

Detection of Tailings Dams Using High-Resolution Satellite Imagery and a Single Shot Multibox Detector in the Jing–Jin–Ji Region, China

“…Using Hyperion and airborne Hymap hyperspectral data, Riaza et al mapped pyrite mine waste and dumps at the mine site on the Iberian Pyrite Belt [26]. Interferometric Synthetic Aperture Radar (InSAR) can provide millimeter-scale deformation measurements and can be used to investigate the dynamics of consolidation settlement over the tailings impoundment areas [27,28].…”