## 5 Discussion
### Indication of Excess Topography for Secondary Resurgence of GALs  
We had a new idea in addition to the quantitative analysis of the relationship between GALs and excess topography, which was that there is often a risk of secondary resurgence of GALs, so we tried to analyze the conceptual indication of the possible occurrence of landslides--i.e., the relationship between excess topography with the secondary resurgence of GALs. In order to explore the relationship between the secondary resurgence of GALs and excess topography, we needed to obtain the active GAL surfaces with the help of InSAR technology, which can monitor the activity of GALs before their real resurgence. So, based on the study of active landslides in Pan-Sanjiang obtained by [PERSON] et al., and in order to reveal more about the indication of GALs in the natural state of excess topography, the relationship between resurgent GALs that are highly subject to large human activities, inactive GAL depositions and the excess topography were quantitatively analyzed. The quantitative analysis shows that 68.38% of the GAL resurrections in a relatively natural state are distributed on excess topography and that 62.21% of the inactive GAL depositions are distributed on the non-excess topography, which preliminarily indicate that if human activities on the GALs could be reduced, excess topography can effectively indicate the occurrence of GALs. The reason that we preliminarily speculate that there is also an important relationship between the secondary resurrection of GALs and excess topography is that the secondary resurrection of GALs is mainly the secondary resurrection of the depositions. The deposition of the first slide of the landslide may be piled up in the middle of the landslide, and it has not completely slipped down, which may make the place where the deposition is piled up reach the threshold hillslope, so, in the case of external factors such as rainfall, it may trigger a secondary resurgence. However, many of the resurrected GALs are not located on excess topography, which is mainly due to the instability of the foot of the non-excess topography area caused by human activities. Therefore, the current research can only say that the secondary resurrection of GALs is related to the excess topography under the small amount of human damage or the natural state.  
The practice of using the RRIM to identify GALs in the Lengqu River section can be extended to other areas, and because the accuracy of the DEM used in this research is only 12.5 m, some smaller landslides are difficult to identify, so using publicly available, higher-accuracy DEM data can theoretically identify more ancient landslides. Additionally, the landslides identified based on the RRIM can provide sample support for regional landslide susceptibility assessments in the future. At the same time, the concept of excess topography can also be applied to other wider areas or to try to extract excess topography by using higher-precision DEM data, but the key to the application is to be able to select the appropriate threshold hillslope for landslides to be studied for the area. One of the disadvantages of the RRIM method is that it can only identify ancient landslides where the terrain has not been damaged, and the landslide contours could be wrongly traced if the pattern of landslide interpretation by the RRIM is not mastered. Another disadvantage is that only landslides prior to the monitored DEM time can be interpreted; one of the key points to extract the excess topography of a certain area is to be able to select the right threshold hillslope for the study area, which means that the selection of the threshold hillslope requires a large amount of analysis.