AUTHOR=Cao Zhongcheng , Wang Teng TITLE=Water-temperature controlled deformation patterns in Heifangtai loess terraces revealed by wavelet analysis of InSAR time series and hydrological parameters JOURNAL=Frontiers in Environmental Science VOLUME=10 YEAR=2022 URL=https://www.frontiersin.org/journals/environmental-science/articles/10.3389/fenvs.2022.957339 DOI=10.3389/fenvs.2022.957339 ISSN=2296-665X ABSTRACT=

Loess deposits are widely distributed in western and central China. Because loess is wet-collapsible, loess mass is prone to failure after water infiltration. Heifangtai, composed of two adjacent typical loess platforms located in the Loess Plateau beside the Yellow River, has experienced hundreds of landslides in the past few decades. Here, we derived surficial time-series deformation, velocity, and amplitude of seasonality from the Sentinel-1 SAR images acquired from October 2014 to March 2021 in the Heifangtai region and studied their relation with precipitation, temperature, and irrigation applying wavelet analysis. The decomposed velocities show that not only a large amount of along-slope deformation occurred surrounding the terrace but also a significant subsidence in the residential area in the middle of the platform was observed. The high-seasonality areas are distributed along the Yellow River and on the terrace consistent with other water sources, e.g., springs and irrigation, revealing a promotion of a periodic water-involved process on deformation in loess. Through the wavelet analysis, we found that the temperature is almost in phase with the uplift velocity when the temperature is below the freezing point. The precipitation precedes the surface displacement of ∼1 to 2 months for water penetration. The comparison between irrigation volumes and averaged displacements suggests that irrigation also plays a role in promoting subsidence from March to October but uplift in winter due to frost heave. We highlight that the retrogressions of the terraces in this region may be accelerated by both natural and anthropogenic factors. Careful monitoring and water management are highly recommended for the safety of local residences and infrastructures.