Monitoring and evaluation of gully erosion in China's largest loess tableland based on SBAS-InSAR

Gully erosion is widespread in central China's ecologically fragile loess plateau. However, research on the monitoring and evaluation of large-scale erosion is scarce. Here, we collected 16 pairs of Sentinel-1A images from the rainy season, spanning April 5-October 26, 2019, subsidence is then quantified and its results can indirectly reflect the intensity of erosion on the largest loess plateau in China, the Dongzhiyuan tableland, using small baseline subset synthetic aperture radar interferometry (SBAS-InSAR). The results showed that, the average erosion rate was 9 mm/year, throughout the study area, Surprisingly, the average erosion rate in the gully reached 160 mm/year, the sides of the gully correspond to the most extensive and intense erosion. Heavy rainfall, slope gradients below 15 degrees, changes in groundwater levels due to freeze-thaw action and water infiltration during rainfall, and lack of vegetation due to continued gully side erosion, drive the intense erosion. These results demonstrate the reliable ability of the SBAS-InSAR method in accurately assessing large-scale gully erosion. The InSAR-calculated subsidence demonstrates a strong predictive capability for soil erosion and is generally consistent with previously observed levels of erosion, although much noise interference also occurs. Therefore, in the future InSAR-calculated sedimentation could be used as an indirect measure of erosion levels at multiple watershed scales.