Revealing terrestrial uplift in large-scale land creation areas on the Loess Plateau using InSAR time series data

Abstract

The mountain excavation and city construction (MECC) of the Yan'an New District (YND) project has attracted much attention due to the resulting large-scale creation of land in the Chinese Loess Plateau. Thus, studies related to geohazards caused by MECC project, such as subsidence, have also been widely reported. However, little is known about the land uplift associated with MECC project. The spatiotemporal patterns and mechanisms of uplift associated with MECC project in the YND were investigated in this study. First, the spatiotemporal patterns of uplift in the YND were revealed via small baseline subset InSAR (SBAS-InSAR) analysis of Sentinel-1 data from 2016 to 2019. Then, the surface stress changes associated with the MECC project were calculated based on geotechnical principles. Finally, the correlation between uplift patterns and stress changes was quantified to reveal the uplift mechanisms. The results show a decaying uplift trend with a maximum uplift rate of 24.8 mm/yr, which was detected in the excavated mountain areas and covers 26.6 % of the YND. The MECC project has induced substantial surface stress changes, especially mass load releases of over 1700 kPa in the excavated areas, which was positively correlated with uplift, suggesting that load release controls the spatial pattern and magnitude of uplift. The main intrinsic mechanism driving uplift in the YND is rebound creep resulting from the stress field readjustment in response to mountain excavation (load release), whereas the additional stress brought by human activities is the main external factor inhibiting uplift. These findings contribute to the rational optimization of land creation and subsequent urban construction and can help mitigate hazards associated with large-scale MECC projects.