# Soil and Rockfill Dams Safety Assessment for Henan Province: Monitoring, Analysis and Prediction
## 6 Conclusions  
This study uses Sentinel-1A images and the PS-InSAR technique to monitor the deformation of large-scale soil and rockfill dams in Henan Province and focuses on analyzing the Xiaolangdi Reservoir soil and rockfill dam. The results show that most of the dam bodies of large-scale reservoirs experience deformation or lifting at different locations under long-term monitoring. Among the types of soil and rockfill dams, clay heart wall sand shell dams are relatively stable, while the dams of Baisha Reservoir, Baiguishan Reservoir, and Yanshan Reservoir, and surrounding areas show an overall deformation state, indicating that these reservoirs should be regarded as key concern areas. Taking Xiaolangdi Reservoir as an example, it was found that the deformation rate of the soil and rockfill dam from the top to the bottom exhibited a stepped shape deformation pattern from 2017 to 2021. In addition, by choosing the deformation points of the key parts of the Xiaolangdi soil and rockfill dam, a deformation curve was drawn. The results showed that the upper part of the Xiaolangdi Reservoir soil and rockfill dam had sunk by about 80 mm in nearly 5 years, with a linear trend in the deformation curve. The middle part of the dam had sunk by around 40 mm, with a slower relative deformation  
Figure 20: (**a**) Horizontal displacement map; (**b**) vertical displacement map. compared with the upper part and a slight oscillation. The lower part had sunk by about 20 mm and was always subject to large-scale oscillation. It was found that the middle part of the Xiaolangdi soil and rockfill dam had obvious deformation after analyzing the distribution of cross-section and longitudinal-section, and the longitudinal section analysis showed significant deformation at the top of the Xiaolangdi Reservoir soil and rockfill dam. Furthermore, the MAF-SSA-LSTM dam time series prediction model was established, and it was analyzed that the Xiaolangdi soil and rockfill dam would exhibit obvious deformation in about 2 years. The relationship between the water level and the deformation of Xiaolangdi Reservoir was discussed, and it was found that the high or low water level and rainfall amount have a certain influence on dam deformation. Therefore, after a long period of water level changes, the management department should conduct a check in key areas of the dam body and timely handle any safety hazards. The deformation monitoring of large-scale soil and rockfill dams illustrated that the application of the time series InSAR technique can survey the deformation of dams on a large scale, and with long-term monitoring results, the overall deformation pattern of soil and rockfill dams can be revealed. This indicates that the time series InSAR deformation monitoring method can provide reliable analysis and data support for disaster prevention and control of large-scale hydraulic structures. In this study, only Sentinel-1A ascending orbit images were used for deformation monitoring of large-scale soil and rockfill dams in Henan Province. This can only obtain the deformation information in the LOS direction. In the future, ascending and descending orbit data can be used to invert the three-dimensional deformation information of soil and rockfill dams to obtain a more accurate deformation pattern. Additionally, due to confidentiality reasons, this study lacks contemporaneous leveling data for precise verification. Conceptualization, H.L. ; methodology, M.Z. ; software, B.Z. ; validation, W.Z. ([PERSON]); formal analysis, Y.W. ; investigation, G.L. ; resources, Z.B. ; data curation, W.Z. ([PERSON]); writing--original draft preparation, H.L. ; writing--review and editing, M.Z. All authors have read and agreed to the published version of the manuscript. This research was supported by the National Nature Science Foundation of China (grant No. 41901411), in part by the Henan Provincial Science and Technology Research Project (grant No.