The Spatiotemporal Relationship between Landslides and Mechanisms at the Heifangtai Terrace, Northwest China

Abstract

Landslide disasters have occurred frequently in the Chinese Loess Plateau (CLP) due to increased agricultural irrigation. To explore the spatiotemporal relationship between landslides and mechanisms at the Heifangtai terrace, the HFT irrigated area was selected as a typical case study to investigate the fundamental mechanism of the irrigation-induced landslide in the CLP. Multi-temporal remote sensing images, topographic maps, and unmanned aerial vehicle (UAV) photogrammetry data were used to investigate the evolution progress of landslides. Moreover, the evolution mechanism was discussed through topographic analysis, field monitoring, and laboratory testing. The results showed that erosion, collapse, and sliding had occurred at different scales and at different locations in the past 50 years. With an average retrogressive speed of 9.6 × 103 m2 per year, the tableland decreased by 4.9 × 105 m2 from 1967 to 2018, accounting for about 4.5% of its total area. Over 20 landslides and collapses were extracted in the Dangchuan section in the past four years. More than 5.48 × 105 m3 of loess slipped with an average volume of 381 m3 per day. The evolutionary process of the irrigation-induced landslide, which features retrogression, lateral extension, and clustering, began with local failure and ended in a series of slidings. The increase of groundwater level was a slow process, which is the reason for the lagged occurrence of the landslide. The influence of rainfall and irrigation on slope stability was greater than that of the periodic change of the groundwater level. The triggering effect of irrigation and rainfall on the landslide had a time lag due to slow loess infiltration, and the time response among irrigation, rainfall, and groundwater level was 4–6 months. Our findings provide guidance, concerning the planning and controlling of landslide disasters, which is of critical value for human and construction safety.

Effect of collapse-type lateral pressure induced by irrigation

“…In summary, the tension crack in the slope top can be reflected by the distributions of the lateral pressure coefficient and the local safety coefficient, in agreement with actual circumstance, indirectly implying that lateral pressure can influence the slope safety coefficient (Lu et al 2012;Xu et al 2021;Gu et al 2021).…”

“…Below the clay layer are alluvial deposits comprised primarily of well-rounded stones measuring approximately 5-10 cm in diameter and 2-5 m in thickness. The bedrock consists primarily of mudstone and granular mudstone, with small amounts of sandstone and conglomerate (Zhang et al 2022;Zhang et al 2013;Xu et al 2021;Gu et al 2021).…”

“…The lateral pressure coefficient refers to the ratio of effective lateral pressure (σ3) to effective vertical pressure (σ1) in the context of soil compression under semi-infinite conditions (Peng et al 2001;Xu et al 2021;Gu et al 2021). Slope lateral pressure coefficients under variable operating conditions were calculated by numerical simulation (Fig.…”

“…Moreover, infiltrating surface water might lead to a higher groundwater level and increased uplift force, resulting in slope instability. Therefore, the lateral pressure coefficient can exhibit very well the slope deformation characteristics at variable operating conditions (Peng et al 2001;Gu et al 2021;Xu et al 2021).…”

“…This could be due to the ignoring horizontal deformation of the loess upon collapse (Zhang et al 2022;Gu et al 2019). Moreover, the Heifangtai terrace area has been irrigated for more than five decades, the spatial variability of landslides is related to some extent to the predominant direction of horizontal deformation of the terrace overall collapse, and horizontal deformation on the terrace surface develops gradually westward along with the temporal response (Gu et al 2021;Zhang et al 2019;Xu et al 2021). Therefore, studies of the effect of collapse-type lateral pressure on loess landslide have both scientific and practical significance for improving loess landslide-induced disaster theory and precise early warning of loess landslide disasters.…”