## Message Board

Volume 46 Issue 10
Nov.  2021
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Article Contents
##### doi: 10.13203/j.whugis20210130
Funds:

The National Natural Science Foundation of China 41941019

The National Natural Science Foundation of China 41801391

the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project SKLGP2020Z012

• Author Bio:

DAI Keren, PhD, professor, specializes in geohazards early identification, monitoring and early warning, risk prevention based on InSAR and multi-source remote sensing. E-mail: daikeren17@cdut.edu.cn

• Corresponding author: LI Zhenhong, PhD, professor. E-mail: zhenhong.li@chd.edu.cn
• Publish Date: 2021-10-05
•   Objectives  The Sichuan-Tibet railway is not only a state key project in China, but also the most difficult super project in railway construction history due to the most complex terrain and the active geological structure. Interferometric synthetic aperture radar (InSAR) has proved to be a critical tool for detecting and monitoring geohazards because of its wide coverage, high precision, and high efficiency. Howe-ver, due to its side-looking geometry, InSAR faces serious geometric distortions in mountainous areas, particularly in extremely steep high mountain and gorge areas along the Sichuan-Tibet railway.  Methods  Utilizing the full open-access Sentinel-1 data, which has the wide coverage and a short revisiting time, we carry out satellite radar geometric distortion and feasibility analyses along the Sichuan-Tibet railway. Taking into account synthetic aperture radar(SAR) imaging geometry, the variations of the incidence angles across the whole SAR image, and the passive geometric distortions, we present an integrated approach to accurately determine the areas with SAR geometric distortions.  Results  Our results for Sentinel-1 data show that the areas with geometric distortions for observations with a single-orbit (i.e. ascending or descending) reach 31%—35% along the Sichuan-Tibet railway, whilst the geometric distortion areas reduce to 1.5% for observations with both ascending and descending orbits; furthermore, about 35% of the whole area is suitable for joint analyses with both ascending and descending observations.  Conclusions  The quantitative result also reveals the feasibility to use the Sentinel-1 data to detect and monitor geohazards along the Sichuan-Tibet railway from the perspective of geometric distortions. It can not only improve the overall understanding of the applicability of Sentinel-1 based InSAR and the InSAR results interpretation in this area, but also provide a guideline for efficiently selecting other satellite SAR datasets for detecting and monito-ring geological disasters along the Sichuan-Tibet railway.
###### 通讯作者: 陈斌, bchen63@163.com
• 1.

沈阳化工大学材料科学与工程学院 沈阳 110142

Figures(8)  / Tables(1)

## 川藏铁路沿线Sentinel-1影像几何畸变与升降轨适宜性定量分析

##### doi: 10.13203/j.whugis20210130
###### 1. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China2. College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China3. College of Geological Engineering and Geomatics, Chang'an University, Xi'an 710054, China4. Key Laboratory of Western China's Mineral Resources and Geological Engineering, Ministry of Education, Xi'an 710054, China5. School of Engineering, Newcastle University, NewcastleNE1 7RU, England6. Geosciences and Satellite Big Data Research Center of Chang'an University, Xi'an 710054, China
Funds:

The National Natural Science Foundation of China 41941019

The National Natural Science Foundation of China 41801391

the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project SKLGP2020Z012

• Author Bio:

• ###### Corresponding author:LI Zhenhong, PhD, professor. E-mail: zhenhong.li@chd.edu.cn

Abstract:   Objectives  The Sichuan-Tibet railway is not only a state key project in China, but also the most difficult super project in railway construction history due to the most complex terrain and the active geological structure. Interferometric synthetic aperture radar (InSAR) has proved to be a critical tool for detecting and monitoring geohazards because of its wide coverage, high precision, and high efficiency. Howe-ver, due to its side-looking geometry, InSAR faces serious geometric distortions in mountainous areas, particularly in extremely steep high mountain and gorge areas along the Sichuan-Tibet railway.  Methods  Utilizing the full open-access Sentinel-1 data, which has the wide coverage and a short revisiting time, we carry out satellite radar geometric distortion and feasibility analyses along the Sichuan-Tibet railway. Taking into account synthetic aperture radar(SAR) imaging geometry, the variations of the incidence angles across the whole SAR image, and the passive geometric distortions, we present an integrated approach to accurately determine the areas with SAR geometric distortions.  Results  Our results for Sentinel-1 data show that the areas with geometric distortions for observations with a single-orbit (i.e. ascending or descending) reach 31%—35% along the Sichuan-Tibet railway, whilst the geometric distortion areas reduce to 1.5% for observations with both ascending and descending orbits; furthermore, about 35% of the whole area is suitable for joint analyses with both ascending and descending observations.  Conclusions  The quantitative result also reveals the feasibility to use the Sentinel-1 data to detect and monitor geohazards along the Sichuan-Tibet railway from the perspective of geometric distortions. It can not only improve the overall understanding of the applicability of Sentinel-1 based InSAR and the InSAR results interpretation in this area, but also provide a guideline for efficiently selecting other satellite SAR datasets for detecting and monito-ring geological disasters along the Sichuan-Tibet railway.

• 川藏铁路是中国境内连接四川省与西藏自治区的快速铁路，呈东西走向，东起四川省成都市、西至西藏自治区拉萨市，全长达1 543 km[1]。川藏铁路所经地形复杂，沿线海拔呈“台阶式”变化，地形起伏剧烈，在平均高差2 000 m的山谷间“八起八伏”，累积爬升高度超过14 000 m[2]。沿线工程地质条件非常复杂，地质灾害频发，在崇山峻岭中选择一条合适的线路极其困难[3]。开展铁路线路沿线地质灾害隐患点的早期识别与连续监测，对施工初期的线路进行优化调整，对后期保障线路建设和以后的运营安全均具有重要意义。