Today's cities are full of large structures that require very high cost and time to monitor in traditional ways. Existing engineering structures are deformed due to various factors such as landslides, land subsidence, earthquake, flood, explosion and etc. With increasing the number of large engineering structures in cities, experts are looking for a good solution for monitoring these structures to avoid great financial and human damages.  One of the most important huge structures in any country is the dam. In addition to providing drinking water and water for agriculture, dams prevent devastating floods and are able to generate a large amount of hydropower. Therefore, continuous monitoring and study of the displacement and deformation behavior of the dams is essential.
From the past, leveling and ground surveying were carried out to measure the deformation of structures and ground displacements along the vertical direction; but these measurements are time-consuming and costly. Also, the use of precision instruments and deformation sensors are not suitable because of their high cost, time-consuming and complex.
Due to the ability of Radar images and Radar interferometry techniques in the field of monitoring the ground displacement, in this research, we are looking for evaluating the potential of this method for monitoring the dam deformation and displacements. To achieve this goal, we used two sets of radar data which are CosmoSkyMed-X and Sentinel-1A.  
The study area in this study is Daryan earth-fill dam which is located in Kermanshah province. Daryan Dam is a gravel dam with a clay core. The length of the crown of the dam is 368 meters, the width is 15 meters and the height of the foundation is 179 meters. The method used to estimate the displacement of the dam is the Persistent scatterers (PSI) technique. In the time series processing of these images, the PSI method was selected then the star graph and Deloney triangulation were used. In the next step, we used both linear and nonparametric models for displacement estimation. The results were evaluated by applying two different displacement models and finally, the model with higher temporal coherence was selected as the appropriate model and the other model was discarded. In processing the Daryan dam images, the appropriate model for monitoring the displacements with S-1A Radar data was the nonparametric model and for CSK data was linear model.
The results of the accuracy assessment showed that by using CSK and S-1A radar data, we can monitor the earth-fill dam displacements by the precision of 2 and 4 mm which these precisions are acceptable and standard. It is important to note that the results of X-band data due to it's higher resolution, has a higher density of PS points, and higher accuracy. Also, the larger size or greater area of the dam body makes more the density of the PS points and the displacements obtained for these points will be more accurate.
Generally, we can say that the X and C-band radar data have the potential to monitor the earth-fill dam displacements by radar interferometry technique and this method can replace with traditional and costly methods.