Multi‐decadal changes in the relationships between rainfall characteristics and debris‐flow occurrences in response to gully evolution after the 1990–1995 Mount Unzen eruptions

2021 ◽  
Author(s):  
Haruka Tsunetaka ◽  
Yoshinori Shinohara ◽  
Norifumi Hotta ◽  
Christopher Gomez ◽  
Yuichi Sakai
Keyword(s):  
Debris Flow ◽  
Rainfall Characteristics

Research on Motion Characteristics and Formation Mechanism of Debris Flow

2014 ◽  
Vol 711 ◽  
pp. 388-391
Author(s):  
Ji Wei Xu ◽  
Ming Dong Zhang ◽  
Mao Sheng Zhang
Keyword(s):  
Debris Flow ◽  
Formation Mechanism ◽  
Debris Flows ◽  
Catchment Area ◽  
Large Scale ◽  
Large Range ◽  
Extreme Rainfall ◽  
Small Catchment ◽  
Rainfall Characteristics ◽  
Motion Characteristics

On July 9 2013, debris flows occurred around Longchi town with large scale and wide harm, which was a great threat to people's life and property as well as reconstruction work. Debris flow ditch in the surrounding town was studied. This paper focused on loose materials, topography and rainfall characteristics, and explored the formation mechanism of debris flow in Longchi town. The result shows that: a small catchment area in valleys also have the risk of large range of accumulation of debris flow, the debris flow is caused by a lot of loose materials in mountains after earthquake and extreme rainfall. Research results contribute to a better understanding of trigger condition of debris flow after earthquake.

The effects of rainfall regimes and rainfall characteristics on peak discharge in a small debris flow-prone catchment

2019 ◽  
Vol 16 (7) ◽  
pp. 1646-1660 ◽  
Author(s):  
Zhen-lei Wei ◽  
Hong-yue Sun ◽  
Hao-di Xu ◽  
Gang Wu ◽  
Wei Xie
Keyword(s):  
Debris Flow ◽  
Peak Discharge ◽  
Rainfall Characteristics ◽  
Rainfall Regimes

scholarly journals Estimation of debris flow critical rainfall thresholds by a physically-based model

2012 ◽  
Vol 9 (11) ◽  
pp. 12797-12824 ◽  
Author(s):  
M. N. Papa ◽  
V. Medina ◽  
F. Ciervo ◽  
A. Bateman
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Rainfall Threshold ◽  
Richards Equation ◽  
Reduced Form ◽  
Physically Based Model ◽  
Rainfall Characteristics ◽  
South Italy ◽  
Infinite Slope Stability Model ◽  
Physically Based

Abstract. Real time assessment of debris flow hazard is fundamental for setting up warning systems that can mitigate its risk. A convenient method to assess the possible occurrence of a debris flow is the comparison of measured and forecasted rainfall with rainfall threshold curves (RTC). Empirical derivation of the RTC from the analysis of rainfall characteristics of past events is not possible when the database of observed debris flows is poor or when the environment changes with time. For landslides triggered debris flows, the above limitations may be overcome through the methodology here presented, based on the derivation of RTC from a physically based model. The critical RTC are derived from mathematical and numerical simulations based on the infinite-slope stability model in which land instability is governed by the increase in groundwater pressure due to rainfall. The effect of rainfall infiltration on landside occurrence is modelled trough a reduced form of the Richards equation. The simulations are performed in a virtual basin, representative of the studied basin, taking into account the uncertainties linked with the definition of the characteristics of the soil. A large number of calculations are performed combining different values of the rainfall characteristics (intensity and duration of event rainfall and intensity of antecedent rainfall). For each combination of rainfall characteristics, the percentage of the basin that is unstable is computed. The obtained database is opportunely elaborated to derive RTC curves. The methodology is implemented and tested on a small basin of the Amalfi Coast (South Italy).

Time Since Burning and Rainfall Characteristics Impact Post-Fire Debris-Flow Initiation and Magnitude

2021 ◽  
Vol 27 (1) ◽  
pp. 43-56
Author(s):  
Luke A. McGuire ◽  
Francis K. Rengers ◽  
Nina Oakley ◽  
Jason W. Kean ◽  
Dennis M. Staley ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Debris Flow ◽  
Debris Flows ◽  
Numerical Models ◽  
Ground Cover ◽  
Temporal Changes ◽  
Infiltration Capacity ◽  
Rainfall Characteristics ◽  
San Gabriel Mountains ◽  
Fire Debris

ABSTRACT The extreme heat from wildfire alters soil properties and incinerates vegetation, leading to changes in infiltration capacity, ground cover, soil erodibility, and rainfall interception. These changes promote elevated rates of runoff and sediment transport that increase the likelihood of runoff-generated debris flows. Debris flows are most common in the year immediately following wildfire, but temporal changes in the likelihood and magnitude of debris flows following wildfire are not well constrained. In this study, we combine measurements of soil-hydraulic properties with vegetation survey data and numerical modeling to understand how debris-flow threats are likely to change in steep, burned watersheds during the first 3 years of recovery. We focus on documenting recovery following the 2016 Fish Fire in the San Gabriel Mountains, California, and demonstrate how a numerical model can be used to predict temporal changes in debris-flow properties and initiation thresholds. Numerical modeling suggests that the 15-minute intensity-duration (ID) threshold for debris flows in post-fire year 1 can vary from 15 to 30 mm/hr, depending on how rainfall is temporally distributed within a storm. Simulations further demonstrate that expected debris-flow volumes would be reduced by more than a factor of three following 1 year of recovery and that the 15-minute rainfall ID threshold would increase from 15 to 30 mm/hr to greater than 60 mm/hr by post-fire year 3. These results provide constraints on debris-flow thresholds within the San Gabriel Mountains and highlight the importance of considering local rainfall characteristics when using numerical models to assess debris-flow and flood potential.

scholarly journals A simple and feasible process for using multi-stage high-precision DTMs, field surveys and rainfall data to study debris flow occurrence factors of Shenmu area, Taiwan

2012 ◽  
Vol 12 (11) ◽  
pp. 3407-3419 ◽  
Author(s):  
W.-C. Lo ◽  
B.-S. Lin ◽  
H.-C. Ho ◽  
J. Keck ◽  
H.-Y. Yin ◽  
...  
Keyword(s):  
Debris Flow ◽  
High Precision ◽  
Debris Flows ◽  
Airborne Lidar ◽  
Rainfall Characteristics ◽  
Field Surveys ◽  
Sensing Technology ◽  
Multi Stage ◽  
Catchment Areas ◽  
Typhoon Herb

Abstract. The occurrence of typhoon Herb in 1996 caused massive landslides in the Shenmu area of Taiwan. Many people died and stream and river beds were covered by meters of debris. Debris flows almost always take place in the Shenmu area during the flood season, especially in the catchment areas around Tsushui river and Aiyuzih river. Anthropogenic and natural factors that cause debris flow occurrences are complex and numerous. The precise conditions of initiation are difficult to be identified, but three factors are generally considered to be the most important ones, i.e. rainfall characteristics, geologic conditions and topography. This study proposes a simple and feasible process that combines remote sensing technology and multi-stage high-precision DTMs from aerial orthoimages and airborne LiDAR with field surveys to establish a connection between three major occurrence factors that trigger debris flows in the Shenmu area.

scholarly journals Debris Flow Generation Based on Critical Discharge: A Case Study of Xiongmao Catchment, Southwestern China

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 552 ◽  
Author(s):  
Lingfeng Gong ◽  
Chuan Tang ◽  
Jiang Xiong ◽  
Ning Li
Keyword(s):  
Debris Flow ◽  
Solid Particles ◽  
Rainfall Pattern ◽  
K Value ◽  
Rainfall Characteristics ◽  
Rainfall Frequency ◽  
Critical Discharge ◽  
Key Factor ◽  
Discharge Parameters ◽  
Using Data

Generation of debris flows is related to poorly sorted mixtures of soil, catchment topography, and rainfall characteristics. Runoff in a valley resulting from intensive rainfall can induce sediment movement within stream beds or along adjacent banks. The water flow in channels is affected by rainfall parameters such as duration, intensity, cumulative rainfall, etc., and is the key factor in debris movement. In this paper, the rainfall characteristics and occurrence conditions of debris flow in Xiongmao Gully on 26 July 2016 were explored. Using data from field surveys and indoor simulation experiments, evaluations of critical discharge parameters for debris movement were performed. Furthermore, debris distribution and the critical discharge characteristics were analyzed via investigation of the catchment topography and cause of the debris flow, and analysis was made of the critical discharge parameters initiating channel debris movement. A K-value clustering analysis method was applied to characterize the rainfall pattern of the study area and its effects on calculation of debris flow. The results showed that for the debris flow in Xiongmao Gully, the debris initiation in the middle reaches of the gully provided the majority of solid particles for the disaster on 26 July 2016, and the upstream confluent provided catchment. Based on the relationship determined by laboratory tests, the calculated critical discharge was 43.8 m3/s, less than the peak discharge (Qc = 66.7 m3/s) calculated by morphological method. In addition, it was indicated that the dominant rainfall patterns of the studied area were first-quartile and second-quartile, i.e., the rainfall occurred primarily at the early or middle stage of this rainfall event. The critical discharge for the debris flow on 26 July was achieved at 5% rainfall frequency, and the larger runoff volume was generated from a short heavy rainfall. According to specific catchment characteristics, such as distributed hydrological analysis, critical discharge, and rainfall pattern of debris flow, forewarning of a damaging debris flow could be made more effective.

scholarly journals Derivation of critical rainfall thresholds for shallow landslides as a tool for debris flow early warning systems

2013 ◽  
Vol 17 (10) ◽  
pp. 4095-4107 ◽  
Author(s):  
M. N. Papa ◽  
V. Medina ◽  
F. Ciervo ◽  
A. Bateman
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Early Warning Systems ◽  
Shallow Landslides ◽  
Slope Instability ◽  
Richards Equation ◽  
Warning Systems ◽  
Rainfall Characteristics ◽  
Infinite Slope Stability Model ◽  
Critical Rainfall

Abstract. Real-time assessment of debris-flow hazard is fundamental for developing warning systems that can mitigate risk. A convenient method to assess the possible occurrence of a debris flow is to compare measured and forecasted rainfalls to critical rainfall threshold (CRT) curves. Empirical derivation of the CRT from the analysis of past events' rainfall characteristics is not possible when the database of observed debris flows is poor or when the environment changes with time. For debris flows and mud flows triggered by shallow landslides or debris avalanches, the above limitations may be overcome through the methodology presented. In this work the CRT curves are derived from mathematical and numerical simulations, based on the infinite-slope stability model in which slope instability is governed by the increase in groundwater pressure due to rainfall. The effect of rainfall infiltration on landside occurrence is modelled through a reduced form of the Richards equation. The range of rainfall durations for which the method can be correctly employed is investigated and an equation is derived for the lower limit of the range. A large number of calculations are performed combining different values of rainfall characteristics (intensity and duration of event rainfall and intensity of antecedent rainfall). For each combination of rainfall characteristics, the percentage of the basin that is unstable is computed. The obtained database is opportunely elaborated to derive CRT curves. The methodology is implemented and tested in a small basin of the Amalfi Coast (South Italy). The comparison among the obtained CRT curves and the observed rainfall amounts, in a playback period, gives a good agreement. Simulations are performed with different degree of detail in the soil parameters characterization. The comparison shows that the lack of knowledge about the spatial variability of the parameters may greatly affect the results. This problem is partially mitigated by the use of a Monte Carlo approach.

Đặc điểm phân bố mưa trên lãnh thổ Việt Nam

2008 ◽  
Vol 30 (4) ◽  
pp. 418-426
Author(s):  
Phạm Xuân Thành ◽  
Nguyễn Xuân Anh ◽  
Lê Việt Huy ◽  
Lê Như Quân ◽  
Bernard Fontaine ◽  
...  
Keyword(s):  
Viet Nam ◽  
Rainfall Characteristics ◽  
Temporal Study

Spatial and temporal study of rainfall characteristics over Vietnam

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