考虑水热力耦合过程的InSAR冻土活动层厚度估计及冻融灾害风险评价

冻土活动层厚度是多年冻土稳定性及退化情况的重要表征之一，在全球气候转暖大背景下呈显著增加趋势，导致地表变形加剧，引发多种地质灾害。InSAR为大范围、高分辨率活动层厚度估计带来了契机。但是，现有InSAR冻土变化监测未充分考虑冻土活动层中水热力耦合过程，导致形变模型难以准确描述复杂冻土地表形变规律，形变与活动层厚度函数关联不严密，为后续冻融灾害评价带来了极大不确定性。鉴于此，本项目拟建立考虑持续气温变化及降水分布特征的时序InSAR形变监测模型；在此基础上，提出顾及水热力耦合过程的InSAR多年冻土活动层厚度估计方法；最后，开展引入InSAR形变和活动层厚度的冻融灾害风险评估。本项目：1）可提升InSAR冻土监测能力，丰富冰冻圈遥感方法；2）可提高对大面积冻土冻融过程的认识，服务于我国“三极”大科学计划；3）为准确、可靠、快速监测青藏高原地区冻土退化引发的地质灾害提供重要技术支持。

The active layer thickness (ALT) is one of the important indexes reflecting the stability and degeneration of the permafrost and degeneration of permafrost. Under the global climate warming, the obvious increasing of ALT intensifies the surface deformation and triggers geological disasters. Interferometric Synthetic Aperture Radar (InSAR) provides an opportunity for estimating ALT over permafrost with high-resolution and wide coverage. However, the monitoring of permafrost change based on InSAR technique currently does not fully consider the coupling process of moisture-heat-stress field in the active layer over permafrost, which leads to the difficulty of modeling the complex surface deformation law, the unprecise function correlation between surface deformation and ALT, and also brings great uncertainty to the subsequent freezing-thawing risk assessment. Therefore, the project will firstly establish a new MT-InSAR deformation model by considering the influence of the continuous temperature change and the distribution of precipitation. Then the project will develop an ALT estimation method that based on the InSAR-result and the coupled interaction of moisture-heat-stress fields. Finally, the freezing-thawing risk assessment based on InSAR surface deformation and ALT measurements will be carried out. The research results of the project : 1) can improve the monitoring ability of InSAR in frozen soil application, and enrich the methods in the field of cryosphere remote sensing; 2) can improve the understanding of freeze-thaw process in large-scale permafrost areas, and serve Scientific Programme of Earth’s Three Poles in China; 3) can provide important technical support for the exact, reliable and rapid detection of geological hazards caused by permafrost degradation in the Qinghai-Tibet Plateau.