联合InSAR与无人机航测的白鹤滩库区蓄水前地灾隐患广域识别

白鹤滩水电站位于我国西南高陡山区,是我国实施“西电东送”的国家重大工程之一。水库两岸是地质灾害高易发区,传统的地质灾害调查手段存在工作效率低、危险性高、无法覆盖高位隐患点等弊端。联合星载合成孔径雷达干涉测量技术(InSAR)与无人机航测技术应用于广域地灾隐患探测对于库区地灾隐患广域识别、掌握其分布规律及辅助后续重点防治具有重要意义。本文基于142景Sentinel-1卫星升降轨影像,采用时间序列InSAR技术对白鹤滩库区重点库岸段蓄水前两岸活动性坡体进行探测,同时利用无人机航测技术对其进行了野外验证与辅助分析,根据航片生成的数字高程模型(DEM)、数字正射影像图(DOM)、三维模型等航摄数字产品,结合形变与地形地貌特征,确定了32处地灾隐患点。并结合隐患点的形变量级、形变面积、是否涉水、是否具有明确威胁对象等因素给出了防治建议,建立了全面而准确的蓄水前地灾隐患灾害库。最后基于此案例对两种技术优势特长、适用范围以及如何高效联合应用进行了总结。本文揭示了两种技术在广域地灾隐患识别时的结合应用,无人机航测不仅能对InSAR技术探测到的形变区进行验证,同时InSAR也可以指导重点航测区域,提高航测飞行效率。通过结合两项技术提供的实时与历史信息、形变与地质信息可实现综合研判,形成基于空天遥感技术的高效库岸地质灾害综合遥感识别方法。

Identification of potential landslides in Baihetan Dam area before the impoundment by combining InSAR and UAV survey

Baihetan Dam is located in the high and steep mountain area of southwest China, which is an important part of national project “West to East power transmission” in China. The two banks of the reservoir are highly prone to geological disasters, and the traditional geological disaster investigation means have obvious shortcomings, such as low efficiency, high risk, and unable to cover potential hazards in upper slope. The application of space-borne synthetic aperture radar interferometry (InSAR) and unmanned aerial vehicle (UAV) aerial survey technology for the identification of potential landslides in wide-area is of great significance for identifying potential landslides, understanding their distribution characteristics and mitigating the disaster. In this paper, based on 142 Sentinel-1 satellite images, active slopes with clear displacements were identified on both banks of Baihetan Dam area before impoundment by using sequential InSAR technology. Meanwhile, UAV aerial survey technology was used to verify and analyze the active slopes. According to digital aerial photography products such as DEM, DOM and 3D model, and 32 potential landslides were identified. Combined with the factors of displacement magnitude, displacement area, whether the potential landslides are involved in water and the threating objects, the prevention and control suggestions were given, and a comprehensive and accurate database of potential landslides before impoundment was established. Finally, the advantages, application scope and the effective combination strategy of these two technologies are summarized based on this case. This paper reveals that during the combination of the two technologies on the potential landslides identification in wide area, not only can UAV survey verify the displacement area monitored by InSAR, but also InSAR could improve the flight efficiency of aerial survey. By combining the real-time and historical information, displacement and geological information provided by the two technologies, an efficient comprehensive space-air remote sensing strategy for potential landslides identification in wide dam area can be achieved.