The Effect of Extreme Rainfall Events on Riverbank Slope Behaviour

Abstract

Many slope failures take place during or after rainfall events. Landslides are one of the tragedies associated with slope failures and often lead to fatal accidents. A study on the effects of extreme rainfall on slope stability considering the historical rainfall data, slope characteristics and properties, and flow boundary conditions was undertaken. This study investigated the behaviour of the Sg Langat slope under the influence of extreme rainfall gathered from historical data. Sg Langat was selected as the research area because of its high riverbank failures. The focus of this study are as follows: 1) to determine the effect of slope angles on slope stability, 2) to assess the development of pore-water pressure based on the changing groundwater levels, and 3) to analyse the influence of extreme rainfall events on the slope behaviour via numerical modelling. This study enhances the understanding of certain slope conditions and contributes to the analysis of slope stability through numerical modelling, making it relatively convenient to observe the soil conditions for determining the slope stability of the research area in regards to the effect of extreme rainfall. The results were obtained with respect to the changes in the pore-water pressure and the factor of safety. It was observed that the pressure changes were different for every channel, demonstrating that the generation of negative pore-water pressure was not directly affected by the type of analysis and the rainfall infiltration alone. Moreover, the slopes on all channels presented were considered unstable because of the considerable changes in the negative pore-water pressure at a relatively shallow depth, causing soil strength reduction. The factor of safety recorded for Channel 1 was the lowest at 0.18, whereas Channel 3 had the highest factor of safety of 1.11 but was still considered unsafe as it fell below the standard safety margin of 1.3. Apart from the different rainfall intensities applied, the geometry of the slopes also affected the slope stability.

Experimental Study on the Accumulation Characteristics and Submergence Degree of Three-Dimensional Granular Rock Landslides in Shallow-Water Areas

“…In this study, the inundation volume of a landslide mass was measured and calculated under 28 experimental conditions, with the inundation rate for each condition calculated according to Equation (1). The results are shown in Table 2 and Figure 11.…”

“…Landslides are common geological hazards that occur when sections of rock and soil on a mountain slope undergo shear displacement along a certain weak structural plane (zone) under the action of gravity and move toward lower parts of a slope as a whole, and it often occurs during or after rainfall events (Nazrien et al [1]; Margielewski and Urban [2]; He et al [3]). Landslides occurring in areas with rivers, reservoirs, lakes, or coasts can generate waves of energy during their rapid entry into the water, causing severe disasters (Rudy and Barry [4]; Mohammed and Fritz [5]; Tan et al [6]; Trinaistich et al [7]; Chen et al [8]).…”

Quantitative Landslide Hazard Assessment Using Frequency Ratio Model: A Case Study from SMK Kundasang, Sabah, Malaysia

“…Intensified and long period of precipitation rate affects the slope stability in a way that increases the pore pressure and shear stress. This condition will reduce the safety factor and exaggerate slope failure [26]. Land use practices that disrupt the land frequently result in slope instability.…”

Estimation of soil erodibility in Peninsular Malaysia: A case study using multiple linear regression and artificial neural networks

“…Soil erosion induced by excessive precipitation and augmented surface runoff together with anthropogenic inference such as urbanization, deforestation, and agriculture lead to land degradation, reduced quality and quantity of arable land, enhanced river sedimentation, and prompting stern geological hazards [ [3] , [4] , [5] ]. Although, the erosion problem occurs along the globe, however, countries with tropical and subtropical climates, such as Malaysia, are particularly vulnerable to soil erosion and its associated challenges due to high rainfall intensities in these regions [ 6 , 7 ].…”