X波段高分辨率SAR数据土石坝表面相干性时序变化分析

本文以深圳公明水库6个中小型土石坝为试验区,利用10景1 m分辨率升降轨X波段Terra SAR影像和坝体附近连续气象站的降雨量数据,研究了坝体表面相干性的时序变化与雷达本地入射角及降雨的关系。试验结果表明,混凝土面板和草坡平均相干性均会随本地入射角增加而减小,同时,草坡表面平均相干性在有微小降雨的情况下就会快速下降0.1～0.2,差分干涉图的噪声增大;混凝土面板对微小的降雨敏感度小,但是在暴雨情况下将导致其表面完全失相干。上述结果表明,针对中小土石坝坡体变形监测应当顾及坝体的坡度及入射角选择合适的雷达成像参数,同时应充分利用降雨资料评估干涉图失相干情况,剔除噪声数据。

Analysis of high-resolution X-band SAR data time-series coherence change of earth-rock dams

This paper studies the effects of radar local incident angle and rainfall on coherence time-series variations of six small and medium dams in Gongming reservoir in Shenzhen, using 10 ascending and descending TerraSAR-X images with resolution of 1 m and rainfall data of the continuous weather stations near the dams. The experimental results show that both of coherence of concrete surface and grass surface decrease with the increase of local incident angle. Even though precipitation is relatively small, the average coherence of grass surface will decrease rapidly by approximately 0.1~0.2, and differential interference fringe will be less clear with more noise. Concrete surface is less sensitive to rainfall, while it still can become completely incoherent in case of heavy rainstorms. We concluded that in deformation monitoring of small and medium earth-rock dams, the slope and incident angle of the dams should be taken into account in order to select the optimal radar imaging parameter, and rainfall data should be used to evaluate the coherence of the surfaces and eliminate noise of interferogram.