Rainfall-Induced Geological Disasters

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Water Erosion and Sediment Transport".

Deadline for manuscript submissions: closed (20 November 2022) | Viewed by 32298

Special Issue Editors


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Guest Editor
Faculty of Engineering, China University of Geosciences, Wuhan, China
Interests: engineering geology; geological disasters; environmental geotechnical engineering; soil–water interaction; permeability of sediments
Department of Civil Engineering, Shanghai University, Shanghai, China
Interests: submarine landslide; free surface flow; engineering geology; geophysical flow; geological disasters; granular rheology; mesh-free methods
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Guest Editor
Department of Civil and Environmental Engineering, University of Aberta, Edmonton, AL, Canada
Interests: geomechanics; landslide; liquefaction; intermediate soil; engineering geology; resilience

Special Issue Information

Dear Colleagues,

Rainfall is a primary cause of geological disasters such as landslides and debris flows, which pose a major natural threat to people, infrastructure, lifelines, and economic activities in many countries. Therefore, understanding the mechanism of rainfall-induced geological disasters and designing effective control and mitigation measures are considered to be societal priorities. Engineering geologists have focused on the effects of rainfall infiltration on soil strength and slope stability in saturated and unsaturated conditions. Hydrologists have concentrated their efforts on the processes that control surface and subsurface stormflow at the hillslope and catchment scale. However, there are significant technical challenges associated with the mechanisms and prevention of rainfall-induced geological disasters.

This Special Issue, “Rainfall-Induced Geological Disasters,” will cover the recent advances and future developments concerning the initiation mechanism, monitoring techniques, forecasting models, early warning, regional risk assessment, mitigation and prevention measures of rainfall-induced geological disasters. In addition to these topics, we invite the submission of original research articles and synthetic reviews on the general topics of field investigations, novel data acquisition techniques, laboratory and model experiment research, numerical approaches, and the application of artificial intelligence approaches.

Prof. Dr. Xingwei Ren
Prof. Dr. Zili Dai
Prof. Dr. Fangzhou Liu
Guest Editors

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Keywords

  • landslides
  • debris flow
  • soil–water interaction
  • rain infiltration
  • triggering rainfall
  • slope stability
  • geodisaster modeling
  • monitoring
  • early warning

Published Papers (15 papers)

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Editorial

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2 pages, 159 KiB  
Editorial
Rainfall-Induced Geological Disasters
by Xingwei Ren, Fangzhou Liu and Zili Dai
Water 2023, 15(11), 2003; https://doi.org/10.3390/w15112003 - 25 May 2023
Viewed by 997
Abstract
The Special Issue “Rainfall-Induced Geological Disasters” focuses on the recent advances in disaster mechanisms, risk assessments and prevention measures for rainfall-induced geological disasters [...] Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)

Research

Jump to: Editorial, Other

18 pages, 11371 KiB  
Article
Characteristics of Debris Flow Activities at Different Scales after the Disturbance of Strong Earthquakes—A Case Study of the Wenchuan Earthquake-Affected Area
by Yu Yang, Chenxiao Tang, Yinghua Cai, Chuan Tang, Ming Chen, Wenli Huang and Chang Liu
Water 2023, 15(4), 698; https://doi.org/10.3390/w15040698 - 10 Feb 2023
Cited by 1 | Viewed by 2269
Abstract
Of the catastrophic earthquakes over the past few decades, the 2008 Wenchuan earthquake triggered the greatest number of landslides and deposited a large amount of loose material on steep terrains and deep gullies, which was highly conducive to the occurrence of post-earthquake debris [...] Read more.
Of the catastrophic earthquakes over the past few decades, the 2008 Wenchuan earthquake triggered the greatest number of landslides and deposited a large amount of loose material on steep terrains and deep gullies, which was highly conducive to the occurrence of post-earthquake debris flows. It is of great importance to clarify the evolution of debris flow activity for hazard evaluation, prediction, and prevention after a strong earthquake, especially in the face of large debris flow hazards. We established a long-time span database consisting of 1668 debris flow events before and after the earthquake, with information including the occurrence time, location, and scale (small, medium, and large). In order to analyze how the environmental background before and after the earthquake controlled the debris flow activity, we examined various controlling factors, including the material source, topography (relative relief and slope degree), rainfall, normalized vegetation index, and lithology. After completing the analysis of the spatial and temporal evolution of the debris flow events in the database, a 10 × 10 km grid was introduced to grade the controlling factors in ArcGIS. Based on the same grid, the density of debris flow events for each scale in different time periods was calculated and graded. We introduced the certainty factor to figure out the spatial–temporal relationships between debris flow activities at each scale and the controlling factors. The results can provide guidance on how to dynamically adjust our strategies for debris flow prevention after a strong earthquake. Lastly, Spearman rank correlation analysis was performed to clarify the variation in the magnitude of the influence of controlling factors on the debris flow activities of different scales with time. This can provide a reference for the dynamic evaluation of debris flow hazards in the Wenchuan earthquake-affected area. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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19 pages, 9896 KiB  
Article
Propagation Modeling of Rainfall-Induced Landslides: A Case Study of the Shaziba Landslide in Enshi, China
by Li Wei, Hualin Cheng and Zili Dai
Water 2023, 15(3), 424; https://doi.org/10.3390/w15030424 - 20 Jan 2023
Cited by 6 | Viewed by 2556
Abstract
Geological disasters, especially landslides, frequently occur in Enshi County, Hubei Province, China. On 21 July 2020, a large-scale landslide occurred in Enshi due to continuous rainfall. The landslide mass blocked the Qingjiang River, formed a dammed lake and caused great damage to surrounding [...] Read more.
Geological disasters, especially landslides, frequently occur in Enshi County, Hubei Province, China. On 21 July 2020, a large-scale landslide occurred in Enshi due to continuous rainfall. The landslide mass blocked the Qingjiang River, formed a dammed lake and caused great damage to surrounding roads and village buildings. In this study, the geomechanical properties of the landslide mass were obtained through field surveys. A three-dimensional topography model of the slope was established using the particle flow code (PFC) and the numerical parameters of the model were calibrated. A 3D discrete element model (DEM) was used to simulate the propagation of Shaziba landslide, and the dynamic behavior of the landslide was divided into five stages. The simulation results show that the landslide movement lasted approximately 1000 s. The maximum average velocity of the landslide reached up to 7.5 m/s and the average runout distance was about 1000 m. The simulated morphology of the landslide deposits was in good agreement with the field data. In addition, the influence of effective modulus on the calculation results was analyzed. The results indicate that the propagation behavior of a landslide and the morphology of landslide deposits are closely related to the effective modulus in the contact model of the PFC3D. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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12 pages, 9474 KiB  
Article
Analyzing Rainfall Threshold for Shallow Landslides Using Physically Based Modeling in Rasuwa District, Nepal
by Bin Guo, Xiangjun Pei, Min Xu and Tiantao Li
Water 2022, 14(24), 4074; https://doi.org/10.3390/w14244074 - 13 Dec 2022
Cited by 2 | Viewed by 1891
Abstract
On 25 April 2015, an M7.8 large earthquake happened in Nepal, and 4312 landslides were triggered during or after the earthquake. The 2015 earthquake happened years ago, but the risk of rainfall-induced landslides is still high. Rainfall-induced shallow landslides threaten both human lives [...] Read more.
On 25 April 2015, an M7.8 large earthquake happened in Nepal, and 4312 landslides were triggered during or after the earthquake. The 2015 earthquake happened years ago, but the risk of rainfall-induced landslides is still high. Rainfall-induced shallow landslides threaten both human lives and economy development, especially in the Rasuwa area. Due to financial conditions and data availability, a regional-scale rainfall threshold can be an effective method to reduce the risk of shallow landslides. A physically based model was used with limited data. The dynamic hydrological model provides the soil moisture and groundwater change, and the infinite slope stability model produces the factor of safety. Remote sensing data, field investigation, soil sample tests, and literature review were used in the model parameterization. The landslide stability condition of 2016 was simulated. In addition, intensity-antecedent rainfall thresholds were defined based on the physically based modelling output. Sixty groups of data were used for validation, and the 15-day intensity-antecedent rainfall threshold has the best performance with an accuracy of 88.33%. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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22 pages, 14557 KiB  
Article
Failure Process Analysis of Landslide Triggered by Rainfall at Volcanic Area: Fangshan Landslide Case Study
by Weiwei Gu, Zinan Li, Cheng Lin, Faming Zhang, Menglong Dong, Yukun Li and Chang Liu
Water 2022, 14(24), 4059; https://doi.org/10.3390/w14244059 - 12 Dec 2022
Cited by 2 | Viewed by 1357
Abstract
The Fangshan landslide was a rainfall-induced landslide that occurred in a volcanic area in the Fangshan scenic spot, Nanjing, Jiangsu, China. On 25 October 2016, after approximately 10 days of continuous rainfall, a shallow landslide rapidly developed, which triggered slow movement of deep [...] Read more.
The Fangshan landslide was a rainfall-induced landslide that occurred in a volcanic area in the Fangshan scenic spot, Nanjing, Jiangsu, China. On 25 October 2016, after approximately 10 days of continuous rainfall, a shallow landslide rapidly developed, which triggered slow movement of deep mudstone rock. According to the characteristics of the landslide body, measures such as anti-slide piles, anchor cables and drainage were used to reinforce the landslide. Active drainage measures included arranging plant growth zones at the trailing edge of the landslide, and passive drainage measures included arranging pumping wells at the trailing edge of the landslide. It is worth emphasizing that the Fangshan landslide was the first example of a landslide in Jiangsu Province, China that was treated by actively lowering the water pressure. After landslide treatment from 16 May 2017 to 21 January 2018, the Fangshan landslide tended to be stable. However, the stable landslide was reactivated by the rise in groundwater level caused by rainfall and pumping well damage and underwent accelerated downward sliding in July 2020. The Fangshan landslide has caused great damage to the roads and buildings of Fangshan scenic spot, with a direct loss of RMB 6 million and an indirect loss of RMB 95 million. This article discusses the development process of the shallow soil landslide and the underlying deep mudstone rock landslide. The influence of groundwater level variation on the deformation of the shallow soil landslide and deep mudstone rock landslide of the Fangshan landslide are also discussed. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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18 pages, 5581 KiB  
Article
Model Test and Numerical Simulation of Slope Instability Process Induced by Rainfall
by Yongshuai Sun, Ke Yang, Ruilin Hu, Guihe Wang and Jianguo Lv
Water 2022, 14(24), 3997; https://doi.org/10.3390/w14243997 - 7 Dec 2022
Cited by 4 | Viewed by 1716
Abstract
Due to rainfall infiltration, slope instability becomes frequent, which is the main reason for landslide disasters. In this study, the stability of slope affected by rainfall was analyzed using an indoor model test and geo-studio simulation method, and the variation law of phreatic [...] Read more.
Due to rainfall infiltration, slope instability becomes frequent, which is the main reason for landslide disasters. In this study, the stability of slope affected by rainfall was analyzed using an indoor model test and geo-studio simulation method, and the variation law of phreatic line, seepage field, the most dangerous sliding surface, and safety factor with time were studied under rainfall infiltration. Research results showed that under the effect of rainfall, the slope failure presented a typical traction development mode. With the increase of time, the phreatic line of the slope kept rising, the water head keeps increasing, the seepage depth in the slope became deeper, and the slope stability worsened until the slope was damaged. The water head height decreased gradually from the slope left boundary to the right, and the water head width decreased gradually. The soil at the slope back edge was damaged, and the sliding soil accumulated at the slope foot, forming a gentle slope, which increased the shear strength of the slope, making the slope finally reach a stable state. In this process, the overlying soil changed from an unsaturated state to a saturated state, the pore water pressure and soil pressure increased, and then the slope was damaged, both of which decreased. Under high rainfall intensity, the slope was damaged, the soil in the slope was rapidly saturated, and the time required to produce the sliding area was short. When the rainfall intensity was the same, the smaller the slope angle was, the smaller the safety factor was. When the slope angle was the same, the greater the rainfall intensity was, the smaller the safety factor was. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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28 pages, 7686 KiB  
Article
Statistical Analysis of the Potential of Landslides Induced by Combination between Rainfall and Earthquakes
by Chih-Ming Tseng, Yie-Ruey Chen, Chwen-Ming Chang, Ya-Ling Yang, Yu-Ru Chen and Shun-Chieh Hsieh
Water 2022, 14(22), 3691; https://doi.org/10.3390/w14223691 - 15 Nov 2022
Cited by 1 | Viewed by 1763
Abstract
This study analyzed the potential of landslides induced by the interaction between rainfall and earthquakes. Dapu Township and Alishan Township in Chiayi County, southern Taiwan, were included as study areas. From satellite images and the literature, we collected data for multiple years and [...] Read more.
This study analyzed the potential of landslides induced by the interaction between rainfall and earthquakes. Dapu Township and Alishan Township in Chiayi County, southern Taiwan, were included as study areas. From satellite images and the literature, we collected data for multiple years and time series and then used the random forest data mining algorithm for satellite image interpretation. A hazard index for the interaction between earthquakes and rainfall (IHERI) was proposed, and an index for the degree of land disturbance (IDLD) was estimated to explore the characteristics of IHERI under specific natural environmental and slope land use conditions. The results revealed that among the investigated disaster-causing factors, the degree of slope land use disturbance, the slope of the natural environment, and rainfall exerted the strongest effect on landslide occurrence. When IHERI or IDLD was higher, the probability of a landslide also increased, and under conditions of a similar IDLD, the probability of landslides increased as the IHERI value increased, and vice versa. Thus, given the interaction between rainfall and earthquakes in the study area, the effect of the degree of slope land use disturbance on landslides should not be ignored. The results of a receiver operating characteristic (ROC) curve analysis indicated that the areas under the ROC curve for landslides induced by different trigger factors were all above 0.94. The results indicate that the area in which medium–high-level landslides are induced by an interaction between rainfall and earthquakes is large. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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19 pages, 4446 KiB  
Article
Study on the Risk Assessment Method of Rainfall Landslide
by Haoyue Sui, Tianming Su, Ruilin Hu, Dong Wang and Zhengwei Zheng
Water 2022, 14(22), 3678; https://doi.org/10.3390/w14223678 - 14 Nov 2022
Cited by 6 | Viewed by 2556
Abstract
Quantitative risk assessment of landslides has always been the focus and difficulty in the field of landslide research. In this paper, taking Mayang County, Hunan Province as an example, the risk assessment of rainfall-induced landslides was carried out from the regional and individual [...] Read more.
Quantitative risk assessment of landslides has always been the focus and difficulty in the field of landslide research. In this paper, taking Mayang County, Hunan Province as an example, the risk assessment of rainfall-induced landslides was carried out from the regional and individual scales. On the regional scale, the risk factors of geological disasters were analyzed. Based on the slope unit, the risk analysis of slope geological disasters and the vulnerability risk assessment of hazard-bearing bodies were carried out to form the block plan. On an individual scale, based on the analysis of rainfall extreme value, the variation law of landslide seepage field and stability under different rainfall recurrence periods was simulated. Then, the vulnerability of the disaster-bearing body was studied according to the analysis of the impact range and the field investigation. Combined with the evaluation results of landslide hazard and vulnerability of the disaster-bearing body, the life and economic risks under different working conditions were further obtained. Therefore, the research results could provide not only a reference for the risk assessment of rainfall-induced landslides in other regions but also a theoretical basis for the early warning and prediction of landslide disasters. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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15 pages, 4299 KiB  
Article
SPH-Based Numerical Study on the Influence of Baffle Height and Inclination on the Interaction between Granular Flows and Baffles
by Hualin Cheng, Bei Zhang and Yu Huang
Water 2022, 14(19), 3063; https://doi.org/10.3390/w14193063 - 29 Sep 2022
Cited by 3 | Viewed by 2200
Abstract
Arrays of baffles are widely used to prevent and mitigate granular flows (e.g., debris flows and landslides) in mountainous areas. A thorough understanding of the decelerating effect and the impact force of the baffle arrays is essential for engineering design and hazard mitigation. [...] Read more.
Arrays of baffles are widely used to prevent and mitigate granular flows (e.g., debris flows and landslides) in mountainous areas. A thorough understanding of the decelerating effect and the impact force of the baffle arrays is essential for engineering design and hazard mitigation. However, the interaction mechanism of granular flows and baffles is still not fully understood. In this work, numerical simulations based on the smoothed particle hydrodynamics (SPH) method are performed to investigate the influence of baffle height and inclination on the interaction between granular flows and baffles. It is found that the SPH model can well capture the flow kinematics of granular materials through the baffles and can obtain the impact force acting on the baffle structures. The results indicate that the performance of baffles is affected by the overflow of granular flows and increasing baffle height can effectively improve the deceleration effect on granular flows. However, the impact force analysis shows that the strength of higher baffle structures also needs to be increased in engineering design. In addition, the peak impact force is found to be closely related to the Froude number Fr. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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23 pages, 9706 KiB  
Article
Influence of Fines Content on the Stability of Volcanic Embankments under Rainfall and Earthquake
by Trong Nam Nguyen, Shima Kawamura, Minh Hieu Dao and Takumi Inaba
Water 2022, 14(13), 2096; https://doi.org/10.3390/w14132096 - 30 Jun 2022
Cited by 1 | Viewed by 1814
Abstract
This study aims to investigate the effects of fine content on the mechanical behavior of embankments constructed from volcanic soil subjected to rainfall and earthquake. To accomplish this purpose, a series of 1 g model experiments on slopes using Komaoka volcanic coarse-grained soils [...] Read more.
This study aims to investigate the effects of fine content on the mechanical behavior of embankments constructed from volcanic soil subjected to rainfall and earthquake. To accomplish this purpose, a series of 1 g model experiments on slopes using Komaoka volcanic coarse-grained soils as materials was conducted with a spray nozzle and shaking table. In the experiments, shear strain, acceleration, pore water pressure, and saturation degree were monitored and measured to provide an understanding of the failure mechanism of the model embankment with different fine particle contents during post-rainfall earthquakes. The results show that the increase in the fines content of the volcanic soil reduces the permeability of the volcanic embankment but has no significant effect on rainfall-induced slope failure until the shear strain is less than 6%. Moreover, the seismic resistance of volcanic slopes subjected to previous rainfall increases when the fine particle content increases to a certain threshold of about 27%. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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15 pages, 3708 KiB  
Article
Algorithm Implementation of Equivalent Expansive Force in Strength Reduction FEM and Its Application in the Stability of Expansive Soil Slope
by Qiang Yang, Rongjian Li, Shibin Zhang, Rongjin Li, Weishi Bai and Huiping Xiao
Water 2022, 14(10), 1540; https://doi.org/10.3390/w14101540 - 11 May 2022
Cited by 5 | Viewed by 1420
Abstract
Loss of matric suction during rain has an important effect on the instability of expansive soil slope. A new device was designed for testing the expansive force in order to propose and determine the equivalent expansive force corresponding to the matric suction. First, [...] Read more.
Loss of matric suction during rain has an important effect on the instability of expansive soil slope. A new device was designed for testing the expansive force in order to propose and determine the equivalent expansive force corresponding to the matric suction. First, the internal relation between the matric suction and the corresponding equivalent expansive force of unsaturated expansive soil was analyzed. Then, numerical algorithm implementation of the equivalent expansive force was discussed, and the equivalent expansive force was introduced into the strength reduction finite element method (FEM). Finally, the equivalent effects of the matric suction and the equivalent expansive force were compared and analyzed by evaluating the stability of an unsaturated expansive soil slope. The results show that the new testing device significantly improves the accuracy of the expansive force test and shortens the testing time. The relation between the matric suction and the equivalent expansive force with the change in initial water content is obvious. The equivalent expansive force can reflect the macro contribution of matric suction to unsaturated expansive soil, and the developed strength reduction FEM based on the equivalent expansive force can be used to evaluate the rainfall-induced instability of an expansive soil slope caused by the decrease in matric suction resulting from the rainfall infiltration. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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16 pages, 7577 KiB  
Article
Function of a Deep-Buried Isolated Trench and Its Effect on Cracking Failure Characteristics of a Slope under Artificial Rainfall
by Lei Wang, Rongjian Li, Shibin Zhang, Rongjin Li, Weishi Bai and Huiping Xiao
Water 2022, 14(7), 1123; https://doi.org/10.3390/w14071123 - 31 Mar 2022
Cited by 7 | Viewed by 2313
Abstract
When tests are conducted on the field slope under artificial rainfall, because artificial rainfall is often limited to implementation in the mode of local rainfall, there is a boundary constraint effect between the rainfall area and the non-rainfall area, which is manifested in [...] Read more.
When tests are conducted on the field slope under artificial rainfall, because artificial rainfall is often limited to implementation in the mode of local rainfall, there is a boundary constraint effect between the rainfall area and the non-rainfall area, which is manifested in the lateral infiltration of rainwater and the slope deformation retardation of non-rainfall area to the rainfall area. Firstly, a deep-buried isolated trench was proposed to solve these boundary constraints. Then, field cracking tests and the corresponding numerical simulation were conducted under rainfall. In the end, the response of water content and the cracking failure characteristics of the slope were analyzed during rainfall, and the effect of a deep-buried isolated trench on the cracking characteristics of the slope was evaluated. The results indicate that the proposed deep-buried isolated trench measure can effectively eliminate the deformation retardation resulting from the adjacent non-rainfall area so a through-crack parallel to the slope shoulder that extended on both sides of the boundary of the rainfall slope was observed at the slope crest and a cracking failure in the shape of the overall downward cutting was realized. As the crack occurred, the rainwater infiltration further aggravated expansion of depthwise cracks, and a local sliding zone was formed in the upper part of the slope. The deep-buried isolated trench solves the boundary constraints, such as lateral infiltration of rainwater and deformation retardation, and can provide an effective technical measure for the field slope test under artificial rainfall. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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21 pages, 6474 KiB  
Article
Physical Modeling for Large-Scale Landslide with Chair-Shaped Bedrock Surfaces under Precipitation and Reservoir Water Fluctuation Conditions
by Shangtao Pan, Wei Gao and Ruilin Hu
Water 2022, 14(6), 984; https://doi.org/10.3390/w14060984 - 21 Mar 2022
Cited by 4 | Viewed by 2380
Abstract
The deformation and failure mechanisms of historical landslides, characterized with different types of bedrock surface shapes which are known to have been induced by rainfall and reservoir water fluctuations, is an important issue currently being addressed by many researchers. The Zhaoshuling Landslide of [...] Read more.
The deformation and failure mechanisms of historical landslides, characterized with different types of bedrock surface shapes which are known to have been induced by rainfall and reservoir water fluctuations, is an important issue currently being addressed by many researchers. The Zhaoshuling Landslide of the Three Gorges Reservoir Region, which was characterized with a chair-shaped bedrock surface under rainfall and reservoir water fluctuation conditions, was selected as an example in this study’s physical modeling process. The results of different parameters, including the displacements, pore water pressure, and total soil pressure during the landslide event, revealed that the Zhaoshuling Landslide with a chair-shaped bedrock surface had been extremely sensitive to heavy rainfall coupled with the rapid lowering of the water levels. Then, based on the data analysis results of the monitoring of the rainfall and groundwater levels, as well as the reservoir water levels, a conceptual model was put forward to explain the failure mechanisms. It was believed that the chair-shaped bedrock at the toe of the slope had been subjected to a localized zone of high transient pore water pressure, which had significantly adverse effects on the mechanisms of the slope stability. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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19 pages, 5972 KiB  
Article
Water Field Distribution Characteristics under Slope Runoff and Seepage Coupled Effect Based on the Finite Element Method
by Shanghui Li, Zhenliang Jiang, Yun Que, Xian Chen, Hui Ding, Yi Liu, Yiqing Dai and Bin Xue
Water 2021, 13(24), 3569; https://doi.org/10.3390/w13243569 - 13 Dec 2021
Cited by 5 | Viewed by 2554
Abstract
The unsaturated seepage field coupled with heavy rainfall-induced surface flow mainly accounts for the slope instability. If the slope contains macropores, the coupled model and solution process significantly differ from the traditional one (without macropores). Most of the studies on the variation of [...] Read more.
The unsaturated seepage field coupled with heavy rainfall-induced surface flow mainly accounts for the slope instability. If the slope contains macropores, the coupled model and solution process significantly differ from the traditional one (without macropores). Most of the studies on the variation of the water field under the coupled effect of runoff and seepage on the slope did not consider the macropore structure. In this paper, two coupled Richards equations were used to describe the MF (Macropore Flow), and along with the kinematic wave equation, they were applied to establish a coupled model of SR (Slope Runoff) and MF. The numerical solving of the coupled model was realized by the COMSOL PDE finite element method, and an innovative laboratory test was conducted to verify the numerical results. The effects of different factors (i.e., rainfall intensity, rainfall duration, saturated conductivity, and slope roughness coefficient) on water content and ponding depth with and without macropores were compared and analyzed. The results show that infiltration is more likely to happen in MF than UF (Unsaturated Flow, without macropore). The depths of the saturation zone and the wetting front of MF are obviously greater than those of UF. When SR occurs, rainfall duration has the most significant influence on infiltration. When macropores are considered, the ponding depth is smaller at the beginning of rainfall, while the effects are not obvious in the later period. Rain intensity and roughness coefficient have significant influences on the ponding depth. Therefore, macropores should not be ignored in the analysis of the slope seepage field. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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Other

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15 pages, 5135 KiB  
Technical Note
Hazard Zonation and Risk Assessment of a Debris Flow under Different Rainfall Condition in Wudu District, Gansu Province, Northwest China
by Shuai Zhang, Ping Sun, Yanlin Zhang, Jian Ren and Haojie Wang
Water 2022, 14(17), 2680; https://doi.org/10.3390/w14172680 - 29 Aug 2022
Cited by 5 | Viewed by 1537
Abstract
Debris flows induced by heavy rainfall are a major threat in Northwest and Southwest China, due to its abrupt occurrence and long runout. In light of this, this work presents the runout simulation and risk assessment of the Boshuigou debris flow under different [...] Read more.
Debris flows induced by heavy rainfall are a major threat in Northwest and Southwest China, due to its abrupt occurrence and long runout. In light of this, this work presents the runout simulation and risk assessment of the Boshuigou debris flow under different rainfall conditions in Wudu district, Gansu Province, Northwest China. Based on field reconnaissance, the geomorphological feature and main source of the Boshuigou debris flow were described. With the application of the FLO-2D simulation, the potential flow depth and flow extent of the Boshuigou debris flow under 100-year return-period rainfall and 50-year return-period rainfall were calculated. The maximum flow velocities of the Boshuigou debris flow under the 100-year return-period rainfall and 50-year return-period rainfall were 5.46 and 5.18 m/s, respectively. Accordingly, the maximum flow depths were 5.85 and 5.57 m. Then, the hazard zonation was conducted in combination of the construction and other properties within the potential impact zone, and the risk assessment of the Boshuigou debris flow under the 100-year return-period rainfall and 50-year return-period rainfall was finally completed. This work presents a method for debris flow risk assessment considering the solid source and water flow, which can provide a basic reference for mitigation and reduction of geohazards induced by torrential rainfall. Full article
(This article belongs to the Special Issue Rainfall-Induced Geological Disasters)
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