基于多时相InSAR技术的黄河三角洲三维地表形变监测与动力学机理分析

The Yellow River delta, the typical coastal region in China, undergoes severe land subsidence due to multiple factors. The land subsidence results in Yellow River delta increasingly vulnerable to secondary disasters; meanwhile normal social economy of the local citizens and ecology environment are highly threatened by the ongoing rapid land subsidence. Therefore, it will be of great significance in characterizing the full and detail spatial and temporal distribution and evolution of the land subsidence, processing its causing, providing technological and decision support for disaster prevention and mitigation, scientifically guiding the natural resources development and utilization, protecting the ecological environment of Yellow River delta sustainable development..As a new type of Earth observation technique, InSAR has the advantages of large coverage, high spatial and temporal resolution and high accuracy and has been widely used in many geosciences fields, especially in surface deformation disaster monitoring field. However, affected by many factors, the monitoring accuracy and application field of traditional InSAR are greatly limited. In order to overcome the limitations and improve detection ability and accuracy, time series InSAR technique, represented by persistent scatterer (PS), distributed scatterer (DS) InSAR and small baseline subset (SBAS) InSAR, were developed to eliminate the errors of traditional InSAR and provide long time high accuracy, high spatial and temporal resolution surface deformation results..Taking the large area and complicated land subsidence of Yellow River delta as the research object, we will study the method to obtain high precision three-dimensional surface deformation utilizing time series InSAR technique over the special environment area in coastal region. The spatial and temporal distribution and evolution characterization of whole surface deformation and regional land subsidence will be analyzed basing on the displacement results. Dynamics mechanism of regional land subsidence in oil field will be modeled and analyzed using reasonable models and efficient inversion algorithm. Further research is focusing on the interpretation of the deformation mechanism according to the displacement field result and field data. All these studies will extend the depth and breadth of the application of time series InSAR over Yellow River delta, reveal the inherent co-movement of surface displacement, natural factors anthropogenic activities and provide a strong guarantee for sustainable development of the Yellow River delta.

黄河三角洲，我国典型的河口海岸带区域，在多重因素共同作用下地面沉降灾害普遍存在。鉴于黄河三角洲地面沉降灾害的复杂性，以及InSAR技术在获取河口海岸带区域地表形变的局限性，如何利用InSAR技术全面获取黄河三角洲地面沉降灾害的时空分布特征与动态演化过程，精细研究其成因机理，已成为黄河三角洲地面沉降灾害研究亟待解决的问题。本课题将利用多平台SAR数据，基于时序分析技术开展针对河口海岸带特殊环境条件下大空间尺度、高精度地表形变监测的方法研究；获取黄河三角洲较为详尽的三维地表形变动态演化图，通过建立合理的反演模型及相应的高效反演算法，选取典型沉降灾害区深入开展动力学机理模型反演分析；结合实地数据资料，综合解译沉降灾害的不同驱动因子与成因机理，最终揭示地表形变、自然因素与人为活动间内在的联动性，为黄河三角洲可持续发展提供强有力的保障。

作为海岸带系统重要组成部分的现代黄河三角洲，经历了复杂的淤进、蚀退以及明显的地面沉降过程。然而，对此复杂三角洲系统演化过程与地表形变时空变化规律的详细认知与理解相对较差。课题基于多源数据，融合多学科对其进行了初步的综合性研究。首先，改进算法程序提高了时序InSAR技术对黄河三角洲地表高相干点的可探测性与形变梯度的探测能力，空间上密集分布的InSAR监测结果使我们获取到了更加翔实可靠的三维地表位移时空变化特征。其次，利用地球物理模型对地下资源开采所诱发的地表形变进行了反演分析，证实了人为因素急剧加速了区域性地面沉降的速率，达到分米量级。同时，基于钻孔数据资料对黄河三角洲整体地层信息进行了构架，并对沉积层的固结时间与压实速率进行了估算，揭示了沉积物固结压实过程的时空分布特征。最后，融合多源数据综合评价了三角洲范围内沉积物固结压实所诱发的长时间尺度的时空沉降特征。结果表明：（1）三角洲内陆相对稳定，而海岸带地区沉降速率为15mm/yr；（2）地面沉降的差异性与三角洲演化及下覆岩层的结构差异具有明显相关性；（3）沉积物的压实作用是三角洲长时间尺度（几十到百年）地面沉降的主要驱动因素；（4）沉积物长期的压实过程具有从最开始的大约70mm/yr到最终的0mm/yr的沉降速率减缓的趋势；（5）三角洲叶瓣形成时间越新，沉降越明显。. 黄河三角洲，作为我国黄河流域以及全球“一带一路”战略的重要组成部分，具有重要的科学、环境保护以及可持续发展等战略研究价值。课题研究成果为黄河三角洲生态环境保护及人为景观格局研究提供了新的思路与启示：（1）详尽可靠的三维地表形变结果为三角洲研究提供了可靠的数据资料支持；（2）三角洲演化过程与地面沉降间的规律为对河口海岸带时空演化过程的认知与理解提供了新的视角与证据；（3）地面沉降的时空分布特征与成因机理研究为海岸带灾害防治、地下资源开发与保护以及生态环境的可持续发展都提供了科学的决策支撑。