Combining TRIGRS and DEBRIS-2D Models for the Simulation of a Rainfall Infiltration Induced Shallow Landslide and Subsequent Debris Flow

Abstract

TRIGRS revealed the responses of the total pressure heads and factors of safety with a depth change under a rainfall infiltration occurring on the Daniao tribe’s hill. The depth distribution of the collapsed zone could be identified under the condition where the factors of safety Fs = 1, and the results could calculate the area and volume. Afterward, DEBRIS-2D used TRIGRS’s results to assess the hazard zone of the subsequent debris flow motion. In this study, the DTM variation analysis results from both of before and after the Daniao tribe’s landslide are used to validate TRIGRS’s simulation, the area and the volume of the collapse zone within 8% and 23% errors, respectively. The real disaster range was depicted from the aerial photo used to validate the hazard zone simulation of DEBRIS-2D within 25% errors. In spite of that, the hazard zone from the simulation still included the real disaster range. The combining method for a rainfall infiltration induced a shallow landslide and subsequent debris flow, which was well-matched on a real disaster range on the Daniao tribe’s hill. Therefore, we believe that the TRIGRS and DEBRIS-2D combining methods would provide a better solution for an assessment of a rainfall infiltration inducing shallow landslide and subsequent debris flow motion. TRIGRS could, therefore, provide the area and depth distribution of the collapsed zone, and DEBRIS-2D could use TRIGRS’s results for subsequent debris flow hazard assessment. Furthermore, these results would be of great help in the management of slope disaster prevention.

The Spatial Model using TRIGRS to determine Rainfall-Induced Landslides in Banjarnegara, Central Java, Indonesia

“…The landslide in this study was triggered by increasing the porewater pressure during rainfall infiltration in line with the elapsed time of precipitation. The failure mechanism was also generally found in many landslide cases to be followed by debris flow (Zhuang et al, 2017;Hsu and Liu, 2019). Moreover, the positive pressure head on the slope surface as shown in Figure 8 indicates the slope was saturated and the rainfall infiltration in each cell of the DEM was calculated in the TRIGRS from the summation of total precipitation (P) and runoff in adjacent cells (Ru).…”

“…A comparison made also showed it is more beneficial to predict a landslide for a specific precipitation threshold, also on the regional scale. Some studies combined TRIGRS with another physical model such as DEBRIS 2D and HSP to evaluate the debris after landslides (Hsu and Liu, 2019;Ciurleo et al, 2018).…”

Real-time shallow landslide hazard assessment on a regional scale

“…It is impractical to achieve sufficient spatial coverage of such data to provide for networkscale analyses. Therefore, geotechnical parameters are assumed based on the soil types and parametric values reported in the literature (e.g., Milne 2008;Cascini et al 2015;Gioia et al 2016;Clarke BG 2018;Hsu and Liu 2019). TRIGRS uses four parameters to approximate soilwater characteristic curves for unsaturated soils in the focus area and to derive the dynamic hydraulic conductivity K(•), as given by:…”

“…The value of 𝛼 can also be derived from other commonly used soil-water characteristic models such as the van Genuchten (VG) model, as shown in Marin (2020) and Marin et al (2021). Along with the four hydraulic parameters, other soil properties data include shear strength parameters (i.e., friction angle and cohesion), unit weight, and diffusivity (e.g., Milne 2008;Cascini et al 2015;Gioia et al 2016;Clarke BG 2018;Hsu and Liu 2019).…”

Editorial for the Special Issue “Water-Induced Landslides: Prediction and Control”

“…Particularly, Yeh and Tsai [4] analyzed the effects of the hydraulic conductivity anisotropy on slope stability using a coupled hydro-mechanical approach. Hsu and Liu [5] used the TRIGRS and DEBRIS-2D codes to predict the soil volume in a rainfall-induced shallow landslide. The remaining four papers presented different approaches for mapping the susceptibility of large areas to rainfall-induced landslides.…”