A Decade of Ground Deformation in Kunming (China) Revealed by Multi-Temporal Synthetic Aperture Radar Interferometry (InSAR) Technique.

Wu Zhu,Wei Qu,Yi Yang,Qin Zhang,Chi-Sheng Wang,Yan Zhang,Wen-Liang Li

doi:10.3390/s19204425

Abstract

Large-scale urbanization has brought about severe ground subsidence in Kunming (China), threatening the stability of urban infrastructure. Mapping of the spatiotemporal variations of ground deformation is urgently needed, along with summarization of the causes of the subsidence over Kunming with the purpose of disaster prevention and mitigation. In this study, for the first time, a multi-temporal interferometric synthetic aperture radar (InSAR) technique with L-band Advanced Land Observation Satellite (ALOS-1) and X-band Constellation of Small Satellites for Mediterranean basin Observation (COSMO-SkyMed) data was applied to Kunming to derive the time series deformation from 2007 to 2016. The annual deformation velocity revealed two severe subsiding regions in Kunming, with a maximum subsidence of 35 mm/y. The comparison of the deformation between InSAR and leveling showed root-mean-square error (RMSE) values of about 4.5 mm for the L-band and 3.7 mm for the X-band, indicating that our results were reliable. We also found that the L-band illustrated a larger amount of subsidence than the X-band in the tested regions. This difference was mainly caused by the different synthetic aperture radar (SAR)-acquired times and imaging geometries between the L- and X-band SAR images. The vertical time series deformation over two severe subsiding regions presented an approximate linear variation with time, where the cumulative subsidence reached 209 mm during the period of 2007–2016. In view of relevant analyses, we found that the subsidence in Kunming was the result of soft soil consolidation, building load, and groundwater extraction. Our results may provide scientific evidence regarding the sound management of urban construction to mitigate potential damage to infrastructure and the environment.

Highlights

Kunming, the capital and largest city of Yunnan province in Southwest China, is located at a longitude of 102◦ 100 –103◦ 400 east and a latitude of 24◦ 230 –26◦ 220 north
Kunming was was aa typical typical lacustrine lacustrine sediment basin that was filled by a large area of soft soil [1]
When ignoring the other factors (e.g., building load, When ignoring the other factors, our result indicates some degree construction), our result indicates some degree of correlation between the ground deformation and of correlation between the ground deformation and soft soil consolidation

Summary

Introduction

The capital and largest city of Yunnan province in Southwest China, is located at a longitude of 102◦ 100 –103◦ 400 east and a latitude of 24◦ 230 –26◦ 220 north. Yunnan–Guizhou plateau in Southwest China, Kunming is surrounded by the Dian Lake to the south and by mountains on the other three sides [1]. As China’s frontier to Southeast Asia and South. As China’s frontier to Southeast Asia and South Asia, large-scale urban urban construction has been implemented in Kunming over theover past the twenty During. Large-scale construction has been implemented in Kunming pastyears. This procedure, a great amount cultivated land and gardens occupied high-rise. Large-scale urbanization brought about a series buildings, and other structures [2]. This large-scale urbanization brought aboutofa geological hazards,hazards, such assuch landslides, subsidence, and and ground fissures

Methods

Results

Conclusion