Analysis on coherence changes of dam surface in TerraSAR Strip mode interferograms

The high resolution images of TerraSAR has made it able to reflect the detail characters of large-scale manmade structures, so monitoring local deformation of large-sized buildings comes to be available. Former research had shown that InSAR phase of the dam surface was stable and consecutive. This paper aimed to make a further proof of the viability of monitoring dam's deformation using 3-meter-resolution strip mode images of TerraSAR. So we made a time series analysis of dam surface's coherence for the next step. Our dataset had eleven images covering three medium size basins of Shenzhen. Coherence of different features in the basin area including dams was extracted to make a comparative analysis. Two different combination methods were designed to create interferometric pairs to find the influence of time baseline and perpendicular baseline to coherence of different cultures. In our research, it was find out that coherence of dam surface was mainly influenced by time baseline. In short time baseline pairs (eleven days), coherence of dam surface was about 0.2 higher than vegetation slope in average. DInSAR process was suitable for short time baseline interferometric pairs, other methods such as PS will be needed for long time baseline interferometric pairs.