Impacts of heterogeneity of saturated hydraulic conductivity on the shallow landslides on the Loess plateau
TANG Honglei1, CHEN Ju1, SHEN Chunying1, ZHANG Ke1, YAO Xinmei2, RAN Qihua3
1. College of Electric Power Engineering, Kunming University of Science and Technology, Kunming 650500, China; 2. College of Civil Engineering, Guizhou University, Guiyang 550025, China; 3. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China
Abstract：[Objective] Shallow soil in the Loess plateau has undergone significant physical changes as a result of the extensive grain for green project, which aims to reduce soil erosion and surface runoff. These changes have altered the hillslope-valley hydrological responses, which are vital processes influencing slope stability. Many studies shows a potential correlation between vegetation restoration and shallow landslides on the Loess plateau. By increasing water infiltration and the vertical variability of soil physical properties, vegetation restoration both induces landslides and increases the volume of landslides. Moreover, shallow landslides have a negative effect on the basin's efforts to restore its ecological balance by sharply increasing the runoff rate and sediment yield rate on the slope surface. However, the impact mechanism of vegetation restoration type and degree on shallow landslides in the Loess plateau is undiscovered, especially how the vertical heterogeneity of shallow soil caused by vegetation restoration affects the occurrence of landslides and the depth of the sliding surface. Therefore, the only way for soil and water conservation and ecological restoration in the new period is to explore the influence mechanisms of vegetation on shallow landslides in the Loess plateau and reduce shallow landslides as much as possible while retaining soil and water.[Methods] To elucidate the impact of vegetation-restoration-induced vertical heterogeneity of soil-saturated hydraulic conductivity on shallow landslides in the Loess plateau, a three-dimensional finite element mesh is established in the Loess plateau's Shejiagou catchment, and simulation accuracy is improved through model calibration and verification of infiltration, runoff, and soil water movement. Forty scenarios are run based on the saturated soil hydraulic conductivity measured under different vegetation restoration conditions, combined with the rainstorm and continuous rainfall processes. The Integrated Hydrological Model is used to simulate the processes of precipitation-infiltration and runoff production, and the soil moisture variables at any time and in any position are coupled to the infinite slope stability model to calculate the slope stability.[Results] The simulation results showed that:(1) As infiltrated water accumulated in a certain soil layer determined by the heterogeneity of soil-saturated hydraulic conductivity, slopes covered by grasslands and shrubs were more unstable than slopes of bare soil, and the risk of landslide under a single rainfall storm increased with the vegetation recovery period. (2) The high soil-saturated hydraulic conductivities in all soil layers which led to quick vertical and lateral drainage, lowered the risks of shallow landslide on forest-covered slopes. (3) The high antecedent water content caused by continuous rainstorm infiltration significantly increased the risks of slope instability in terms of landslide depths and volumes, especially on forest-covered slopes with deeper infiltration paths. (4) The greater the vertical heterogeneity of saturated hydraulic conductivity between layers, the more conducive to water accumulation between layers, and the occurrence of slope instability.[Conclusions] These results reveals the impacts of vertical heterogeneity of soil-saturated hydraulic conductivity caused by vegetation plant restoration on slope stability, which can serve as theoretical guidance for future vegetation restoration as well as soil and water conservation on the Loess plateau.
唐鸿磊, 陈菊, 沈春颖, 张科, 姚新梅, 冉启华. 饱和导水率异质性对黄土高原浅层滑坡的影响[J]. 清华大学学报（自然科学版）, 2023, 63(12): 1946-1960.
TANG Honglei, CHEN Ju, SHEN Chunying, ZHANG Ke, YAO Xinmei, RAN Qihua. Impacts of heterogeneity of saturated hydraulic conductivity on the shallow landslides on the Loess plateau. Journal of Tsinghua University(Science and Technology), 2023, 63(12): 1946-1960.
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2023, Vol. 63 
