上海海塘InSAR形变时空特征监测与非监督聚类演化规律研究

InSAR-Derived Spatiotemporal Deformation Monitoring and Unsupervised Clustering-Based Evolution Pattern Analysis of the Shanghai Seawall

  • 摘要: 上海海塘地处长江流域下游入海口,气候湿润且降水分配不均,水利工程运行安全因此至关重要。本文聚焦上海海塘水利基础设施的形变精细监测与长时间历史演化规律研究,采用2013年至2024年共120景高分辨率长时间序列TerraSAR-X卫星数据,通过合成孔径雷达干涉测量(Interferometric Synthetic Aperture Radar,InSAR)技术与非监督学习方法,系统分析并研究海塘形变的演化规律。针对InSAR形变时间序列噪声影响、形变模式差异不显著导致聚类结果稳定性不足的问题,构建“主成分分析(Principal Component Analysis,PCA)降维—动态时间规整(Dynamic Time Warping,DTW)优化—K-means聚类”的分析框架,从基于统计距离的聚类改进为时间形态相似性约束的判别式聚类结果优化,以增强InSAR形变模式在时间维度上的可分性与稳定性,最终得到不同类别的形变演化模式簇,并结合历史光学影像等辅助资料解析成因。结果表明,海塘沿线显著沉降区域主要分布在填海造陆区、农地区域以及入海口,最大沉降速率达13.76 mm/a。其中,浦东机场附近海塘自2015年起持续沉降;大治河与黄浦江支流入海口及通源东路与观海大道交汇处外侧海塘在观测期间持续沉降;内侧海塘则呈现先快速后缓慢沉降最终趋于稳定的特征。不同模式沉降主要受到填海造陆区土层固结压缩、农地区域地下水过量开采及入海泥沙沉积与潮汐作用叠加等影响。基于聚类簇的形变分析实现了由“点位-阈值”向“模式-解译”的提升,可稳健提取典型形变模式,为海塘分段治理、排查与加固等提供依据与技术支撑。

     

    Abstract: Objective: The Shanghai Seawall is located at the estuary of the lower Yangtze River with a humid climate and uneven precipitation distribution, so the operational safety of hydraulic conservancy projects is of utmost importance. Methods: This study focuses on high-resolution deformation monitoring and long-term evolutionary pattern analysis of the Shanghai seawall. Using a total of 120 high-resolution long-term TerraSAR-X acquisitions from 2013 to 2024, we systematically analyze the deformation evolution of the seawall by integrating Interferometric Synthetic Aperture Radar (InSAR) technique with unsupervised learning methods. To address the instability of clustering results caused by noise contamination i n InSAR deformation time series and the subtle differences among deformation patterns, a hybrid analytical framework is developed, consisting of Principal Component Analysis (PCA) for dimensionality reduction, Dynamic Time Warping (DTW)–based optimization, and K-means clustering. This framework improves traditional statistically distance-based clustering by incorporating temporal shape similarity constraints, thereby enhancing the separability and stability of deformation patterns in the temporal dimension. Distinct deformation evolution pattern clusters are identified and further interpreted using historical optical imagery and ancillary data. Results: The results show that significant subsidence areas along the seawall are mainly distributed in the reclaimed land area, agricultural land area, and estuarine sections, with a maximum subsidence rate of 13.76 mm/a. Among them, the seawalls near the Pudong Airport have been continuously subsiding since 2015. The seawalls located at the estuaries of the Dazhi River and the tributaries of the Huangpu River, and the outer seawalls near the confluence of Tongyuan East Road and Guanhai Boulevard, have subsided persistently throughout the observation period. In contract, the inner seawalls near the confluence of Tongyuan East Road and Guanhai Avenue showed a characteristic of rapid subsidence initially, followed by slow subsidence, and eventually stabilizing. Conclusions: The different subsidence pattern is mainly influenced by the soil consolidation and compression in the reclaimed land area, the over-exploitation of groundwater in the agricultural area, and the combined effects of sedimentation and the tidal forces in the estuary area. Based on the cluster-based analysis of subsidence, the "point-threshold" interpretation has been upgraded to a "pattern-interpretation". This enables the robust extraction of typical deformation evolution patterns, providing a basis and technical support for the segmented management, investigation and reinforcement of seawalls.

     

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