LuTan-1 (LT-1) is a constellation with two full-polarization L-band radar satellites designed by China, and the first satellite was scheduled to be launched in December 2021 and the second one in January 2022. The LT-1 will be operated for deformation monitoring in repeat-pass mode, and for DEM generation in bistatic mode, improving self-sufficiency of SAR data for the field of geology, earthquake, disaster reduction, geomatics, forestry and so on. In this paper, we focused on designing an algorithm for interferometric DEM generation using LT-1 bistatic satellites. The basic principle, main error sources and errors control of the DEM generation algorithm of LT-1 were systematically analyzed. The experiment results demonstrated that: ① The implemented algorithm had rigorous resolution with a theoretic accuracy better than 0.03 m for DEM generation. ② The errors in satellite velocity and Doppler centroid had no obvious effect on DEM accuracy and they could be neglected. While the errors in position, baseline, slant range and interferometric phase had a significant effect on DEM accuracy. And the DEM error caused by baseline error was dominated, followed by the slant range error, interferometric phase error and satellite position error. ③ To obtain an expected DEM accuracy of 2 m, the baseline error must be strictly controlled and its accuracy shall be 1.0 mm or better for Cross-Track and Normal-Direction component, respectively. And the slant range error and interferometric phase error shall be reasonably controlled. The research results were of great significance for accurately grasping the accuracy of LT-1 data products and their errors control, and could provide a scientific auxiliary basis for LT-1 in promoting global SAR technology progress and the generation of high-precision basic geographic data.

The construction of large reservoirs can address the problem of uneven distribution of rivers in time and space, thereby meeting the needs of human production and living. However, the huge elevation of the water level in some areas may modify the distribution of the groundwater level, causing geological disasters, such as surface deformation and landslides. The Yalong reservoir supplies water to the downstream area of Shannan, Tibet; however, since the reservoir started storing water in 2017, the government has discovered two ancient landslides. In this study, to monitor the deformation of the Yalong reservoir since its construction in 2014, we first used synthetic aperture radar (SAR) data and the multidimensional small baseline subset (MSBAS) method to obtain the deformation in the east–west and vertical directions. The result indicated the presence of three large, slow-moving landslides: Landslides Ⅰ and Ⅱ, located on the right bank of the Yalong reservoir, which are consistent with the results obtained by the actual survey, and a new discovery, Landslide Ⅲ, located on the left side of the reservoir. Meanwhile, the experimental results indicated that the dam had undergone obvious deformation after impoundment, which should not be ignored. The global positioning system and interferometric SAR (InSAR) time-series deformation residual data were used to verify the accuracy of the InSAR method. The results also showed that the deformation caused by the three landslides had tended to accelerate after the reservoir's impoundment, and that the failure mode was retrogressive landslide. We found that InSAR plays a vital role in landslide detection and failure mode research around reservoirs, and assists in providing early warning for subsequent landslide disasters.