Ground Deformation Monitoring in Yan'an New District Using Time Series InSAR Method

Urban sprawl results in an increasing area of land being transferred into impervious layers. The city of Yan'an in Shaanxi Province in China, located in the hilly gully area of the Loess Plateau, has implemented the Mountain Excavation and City Construction project, aiming to transform the loess and gully area into an urbanized environment with an area of 78.5 km². The increased flat land will be used to accommodate 400,000 people. The Mountain Excavation and City Construction project on the Loess Plateau is by far the largest geotechnical project in the loess area in the world. It is also an engineering trail to seek the balance between urbanization and sustainable development.

It is challenging to carry out such a large-scale construction in loess gullies where the hydrogeological and engineering conditions are complicated. The loess are naturally prone to deform. Our study applies time-series Interferometric Synthetic Aperture Radar (InSAR) analysis to measure the ground deformation in Yan'an New District. The reported deformation rates reach as large as 70 mm/yr, primarily in the filling areas. The main contributing factor to the deformation is sediment compaction. A stabilization of the new landform is anticipated in several years. Continuous monitoring plays an integral role in mitigating hazards in such loess environment.