scholarly journals Rainfall Warning Model for Rainfall-Triggered Channelized Debris Flow Based on Physical Model Test—A Case Study of Laomao Mountain Debris Flow in Dalian City

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1083
Author(s):  
Yuzheng Wang ◽  
Lei Nie ◽  
Chang Liu ◽  
Min Zhang ◽  
Yan Xu ◽  
...  
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Effective Means ◽  
Field Investigation ◽  
Disaster Mitigation ◽  
Physical Model Test ◽  
Comparison Results ◽  
Geomechanical Analysis ◽  
Critical Rainfall ◽  
Debris Flow Initiation

Debris flows are among the most frequent and hazardous disasters worldwide. Debris flow hazard prediction is an important and effective means of engineering disaster mitigation, and rainfall threshold is the core issue in debris flow prediction. This study selected the Laomao Mountain debris flow in Dalian as the research object and explored the relationship among the percentage of coarse sand content of soil, rainfall conditions and the critical rainfall values that induce debris flows on the basis of field investigation data, combined with the results of a flume test, soil suction measurement and geomechanical analysis. The new multi-parameter debris flow initiation warning models were obtained through the mathematical regression analysis method. The critical rainfall values of debris flows in this area were calculated by the previous research on the mechanism of hydraulic debris flow initiation (HIMM). Lastly, the multi-parameter debris flow initiation warning models were compared and analyzed with the critical rainfall values obtained using the HIMM method and the rainfall information available in historical rainfall data, and the reliability of the models was verified. The comparison results showed that the new multi-parameter debris flow initiation warning models can effectively modify the traditional intensity–duration model and have certain reliability and practical values. They can provide an effectual scientific basis for future work on the monitoring and prediction of debris flow disasters.

scholarly journals Characteristics of rainfall triggering of debris flows in the Chenyulan watershed, Taiwan

2013 ◽  
Vol 13 (4) ◽  
pp. 1015-1023 ◽  
Author(s):  
J. C. Chen ◽  
C. D. Jan ◽  
W. S. Huang
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Extreme Rainfall ◽  
Field Investigation ◽  
Rainfall Event ◽  
Extreme Rainfall Event ◽  
Rainfall Index ◽  
Hourly Rainfall ◽  
Central Taiwan ◽  
Debris Flow Initiation

Abstract. This paper reports the variation in rainfall characteristics associated with debris flows in the Chenyulan watershed, central Taiwan, between 1963 and 2009. The maximum hourly rainfall Im, the maximum 24 h rainfall Rd, and the rainfall index RI (defined as the product RdIm) were analysed for each rainfall event that triggered a debris flow within the watershed. The corresponding number of debris flows initiated by each rainfall event (N) was also investigated via image analysis and/or field investigation. The relationship between N and RI was analysed. Higher RI of a rainfall event would trigger a larger number of debris flows. This paper also discusses the effects of the Chi-Chi earthquake (CCE) on this relationship and on debris flow initiation. The results showed that the critical RI for debris flow initiation had significant variations and was significantly lower in the years immediately following the CCE of 1999, but appeared to revert to the pre-earthquake condition about five years later. Under the same extreme rainfall event of RI = 365 cm2 h−1, the value of N in the CCE-affected period could be six times larger than that in the non-CCE-affected periods.

scholarly journals The temporally varying roles of rainfall, snowmelt and soil moisture for debris flow initiation in a snow-dominated system

2018 ◽  
Vol 22 (6) ◽  
pp. 3493-3513 ◽  
Author(s):  
Karin Mostbauer ◽  
Roland Kaitna ◽  
David Prenner ◽  
Markus Hrachowitz
Keyword(s):  
Soil Moisture ◽  
Debris Flow ◽  
High Intensity ◽  
Debris Flows ◽  
Regional Scale ◽  
Early Summer ◽  
Temporal Separation ◽  
Antecedent Soil Moisture ◽  
Trigger Mechanisms ◽  
Debris Flow Initiation

Abstract. Debris flows represent frequent hazards in mountain regions. Though significant effort has been made to predict such events, the trigger conditions as well as the hydrologic disposition of a watershed at the time of debris flow occurrence are not well understood. Traditional intensity-duration threshold techniques to establish trigger conditions generally do not account for distinct influences of rainfall, snowmelt, and antecedent moisture. To improve our knowledge on the connection between debris flow initiation and the hydrologic system at a regional scale, this study explores the use of a semi-distributed conceptual rainfall–runoff model, linking different system variables such as soil moisture, snowmelt, or runoff with documented debris flow events in the inner Pitztal watershed, Austria. The model was run on a daily basis between 1953 and 2012. Analysing a range of modelled system state and flux variables at days on which debris flows occurred, three distinct dominant trigger mechanisms could be clearly identified. While the results suggest that for 68 % (17 out of 25) of the observed debris flow events during the study period high-intensity rainfall was the dominant trigger, snowmelt was identified as the dominant trigger for 24 % (6 out of 25) of the observed debris flow events. In addition, 8 % (2 out of 25) of the debris flow events could be attributed to the combined effects of low-intensity, long-lasting rainfall and transient storage of this water, causing elevated antecedent soil moisture conditions. The results also suggest a relatively clear temporal separation between the distinct trigger mechanisms, with high-intensity rainfall as a trigger being limited to mid- and late summer. The dominant trigger in late spring/early summer is snowmelt. Based on the discrimination between different modelled system states and fluxes and, more specifically, their temporally varying importance relative to each other, this exploratory study demonstrates that already the use of a relatively simple hydrological model can prove useful to gain some more insight into the importance of distinct debris flow trigger mechanisms. This highlights in particular the relevance of snowmelt contributions and the switch between mechanisms during early to mid-summer in snow-dominated systems.

scholarly journals Discharge of landslide-induced debris flows: case studies of Typhoon Morakot in southern Taiwan

2014 ◽  
Vol 2 (1) ◽  
pp. 315-346
Author(s):  
J.-C. Chen ◽  
M.-R. Chuang
Keyword(s):  
Debris Flow ◽  
Case Studies ◽  
Debris Flows ◽  
Maximum Flow ◽  
Field Investigation ◽  
Typhoon Morakot ◽  
Flow Discharge ◽  
Modeling Software ◽  
Southern Taiwan ◽  
Deposition Depth

Abstract. Three debris-flow gullies, the Hong-Shui-Xian, Sha-Xin-Kai, and the Xin-Kai-Dafo gullies, located in the Shinfa area of southern Taiwan were selected as case studies of the discharge of landslide-induced debris flows caused by Typhoon Morakot in 2009. The inundation characteristics of the three debris flows, such as the debris-flow volume, the deposition area, maximum flow depth, and deposition depth, were collected by field investigations and simulated using the numerical modeling software FLO-2D. The discharge coefficient cb, defined as the ratio of the debris-flow discharge Qdp to the water-flow discharge Qwp, was proposed to determine Qdp, and Qwp was estimated by a rational equation. Then, cb was calibrated by a comparison between the field investigation and the numerical simulation of the inundation characteristics of debris flows. Our results showed that the values of cb range from 6 to 18, and their values are affected by the landslide ratio The empirical relationships between Qdp and Qwp were also presented.

Debris flow initiation from ravel-filled channel bed failure following wildfire in a bedrock landscape with limited sediment supply

2021 ◽  
Author(s):  
Marisa C. Palucis ◽  
Thomas P. Ulizio ◽  
Michael P. Lamb
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Sediment Supply ◽  
Moderate Intensity ◽  
Sandy Sediment ◽  
Channel Network ◽  
Sediment Yields ◽  
First Order ◽  
Dry Ravel ◽  
Debris Flow Initiation

Steep, rocky landscapes often produce large sediment yields and debris flows following wildfire. Debris flows can initiate from landsliding or rilling in soil-mantled portions of the landscape, but there have been few direct observations of debris flow initiation in steep, rocky portions of the landscape that lack a thick, continuous soil mantle. We monitored a steep, first-order catchment that burned in the San Gabriel Mountains, California, USA. Following fire, but prior to rainfall, much of the hillslope soil mantle was removed by dry ravel, exposing bedrock and depositing ∼0.5 m of sandy sediment in the channel network. During a one-year recurrence rainstorm, debris flows initiated in the channel network, evacuating the accumulated dry ravel and underlying cobble bed, and scouring the channel to bedrock. The channel abuts a plowed terrace, which allowed a complete sediment budget, confirming that ∼95% of sediment deposited in a debris flow fan matched that evacuated from the channel, with a minor rainfall-driven hillslope contribution. Subsequent larger storms produced debris flows in higher-order channels but not in the first-order channel because of a sediment supply limitation. These observations are consistent with a model for post-fire ravel routing in steep, rocky landscapes where sediment was sourced by incineration of vegetation dams—following ∼30 years of hillslope soil production since the last fire—and transported downslope by dry processes, leading to a hillslope sediment-supply limitation and infilling of low-order channels with relatively fine sediment. Our observations of debris flow initiation are consistent with failure of the channel bed alluvium due to grain size reduction from dry ravel deposits that allowed high Shields numbers and mass failure even for moderate intensity rainstorms.

Study on the Effect of Debris Flows from Guanba River on Qiong Lake, Sichuan, China

2012 ◽  
Vol 599 ◽  
pp. 709-715 ◽  
Author(s):  
Xue Li Wei ◽  
Yun Long Qi ◽  
Qian Gong Cheng ◽  
Ning Sheng Chen
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Environmental Problem ◽  
Water Area ◽  
Sediment Deposition ◽  
Disaster Mitigation ◽  
Mountain Slope ◽  
Change Pattern ◽  
Push Forward ◽  
Deep Water Area

Sediment deposition caused by debris flows and floods is an important process controlling the evolution and regression of lake, and even a pervasive environmental problem. Qiong Lake is regards as a “bright phearl of the altiplano” in the Yunnan Plateau, and because debris flows construct a vital links between mountain slope and Qiong Lake, so the debris flows drove by rainfall will control the evolution rule of rift lakes. Based on the data of lake shorelines of Qiong Lake, it was found that the shoreline was push forward by 665 m since 1998. In addition, in the recent 30 years, turbidity current deposits have generated underwater levee and other landscapes in the deep water area of Qiong River. This paper has analyzed the matter migration process induced by debris flows, and presented the regime change pattern of debris flow along river channel and corresponding mechanical mechanism, mainly revealed the submarine transportation and deposition pattern of debris flow. The above studies provide a helpful way of comprehending the formation mechanism of turbidity flow induced by debris flow, and the transportation pattern. Based on severe sediment deposition catastrophes in this kind of rift lakes from debris flows and floods, disaster mitigation must be planned and appropriate engineering countermeasures put in place as soon as possible.

scholarly journals Debris-flow activity in five adjacent gullies in a limestone mountain range

2015 ◽  
Vol 42 (1) ◽  
Author(s):  
Klaus Schraml ◽  
Markus Oismüller ◽  
Markus Stoffel ◽  
Johannes Hübl ◽  
Roland Kaitna
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
National Park ◽  
Regional Scale ◽  
Field Investigation ◽  
Mountain Range ◽  
Sediment Sources ◽  
Aerial Vehicle ◽  
Flow Activity ◽  
Local Variability

Abstract Debris-flows are infrequent geomorphic phenomena that shape steep valleys and can repre-sent a severe hazard for human settlements and infrastructure. In this study, a debris-flow event chro-nology has been derived at the regional scale within the Gesäuse National Park (Styria, Austria) using dendrogeomorphic techniques. Sediment sources and deposition areas were mapped by combined field investigation and aerial photography using an Unmanned Aerial Vehicle (UAV). Through the analysis of 384 trees, a total of 47 debris-flows occurring in 19 years between AD 1903 and 2008 were identified in five adjacent gullies. Our results highlight the local variability of debris-flow activi-ty as a result of local thunderstorms and the variable availability of sediment sources.

scholarly journals Atmospheric circulation patterns, cloud-to-ground lightning, and locally intense convective rainfall associated with debris flow initiation in the Dolomite Alps of northeastern Italy

2016 ◽  
Vol 16 (2) ◽  
pp. 509-528 ◽  
Author(s):  
S. Jeffrey Underwood ◽  
Michael D. Schultz ◽  
Metteo Berti ◽  
Carlo Gregoretti ◽  
Alessandro Simoni ◽  
...  
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Lightning Flash ◽  
Synoptic Scale ◽  
Convective Rainfall ◽  
Spatial And Temporal Scales ◽  
Circulation Patterns ◽  
Unconsolidated Material ◽  
Northeastern Italy ◽  
Debris Flow Initiation

Abstract. The Dolomite Alps of northeastern Italy experience debris flows with great frequency during the summer months. An ample supply of unconsolidated material on steep slopes and a summer season climate regime characterized by recurrent thunderstorms combine to produce an abundance of these destructive hydro-geologic events. In the past, debris flow events have been studied primarily in the context of their geologic and geomorphic characteristics. The atmospheric contribution to these mass-wasting events has been limited to recording rainfall and developing intensity thresholds for debris mobilization. This study aims to expand the examination of atmospheric processes that preceded both locally intense convective rainfall (LICR) and debris flows in the Dolomite region. 500 hPa pressure level plots of geopotential heights were constructed for a period of 3 days prior to debris flow events to gain insight into the synoptic-scale processes which provide an environment conducive to LICR in the Dolomites. Cloud-to-ground (CG) lightning flash data recorded at the meso-scale were incorporated to assess the convective environment proximal to debris flow source regions. Twelve events were analyzed and from this analysis three common synoptic-scale circulation patterns were identified. Evaluation of CG flashes at smaller spatial and temporal scales illustrated that convective processes vary in their production of CF flashes (total number) and the spatial distribution of flashes can also be quite different between events over longer periods. During the 60 min interval immediately preceding debris flow a majority of cases exhibited spatial and temporal colocation of LICR and CG flashes. Also a number of CG flash parameters were found to be significantly correlated to rainfall intensity prior to debris flow initiation.

scholarly journals Triggering conditions and depositional characteristics of a disastrous debris flow event in Zhouqu city, Gansu Province, northwestern China

2011 ◽  
Vol 11 (11) ◽  
pp. 2903-2912 ◽  
Author(s):  
C. Tang ◽  
N. Rengers ◽  
Th. W. J. van Asch ◽  
Y. H. Yang ◽  
G. F. Wang
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Field Investigation ◽  
Gansu Province ◽  
Northwestern China ◽  
Catastrophic Event ◽  
Catchment Areas ◽  
Triggering Conditions ◽  
Geomorphological Features ◽  
Triggering Rainfall

Abstract. On 7 August 2010, catastrophic debris flows were triggered by a rainstorm in the catchments of the Sanyanyu and Luojiayu torrents, Zhouqu County, Gansu Province northwestern China. These two debris flows originated shortly after a rainstorm with an intensity of 77.3 mm h−1 and transported a total volume of about 2.2 million m3, which was deposited on an existing debris fan and into a river. This catastrophic event killed 1765 people living on this densely urbanised fan. The poorly sorted sediment contains boulders up to 3–4 m in diameter. In this study, the geomorphological features of both debris flow catchment areas are analyzed based on the interpretation of high-resolution remote sensing imagery combined with field investigation. The characteristics of the triggering rainfall and the initiation of the debris flow occurrence are discussed. Using empirical equations, the peak velocities and discharges of the debris flows were estimated to be around 9.7 m s−1 and 1358 m3 s−1 for the Sanyanyu torrent and 11 m s−1 and 572 m3 s−1 for the Luojiayu torrent. The results of this study contribute to a better understanding of the conditions leading to catastrophic debris flow events.

scholarly journals Run-out Effects of Debris Flows Based on Numerical Simulation

2016 ◽  
Vol 10 (1) ◽  
pp. 848-858
Author(s):  
Jun Wang ◽  
Yan Yu ◽  
Xinfeng Wei ◽  
Qinghua Gong ◽  
Haixian Xiong
Keyword(s):  
Numerical Simulation ◽  
Land Use ◽  
Debris Flow ◽  
Debris Flows ◽  
Flow Simulation ◽  
Simulation Method ◽  
Disaster Mitigation ◽  
Return Periods ◽  
Spatial Risk ◽  
Simulation Results

Debris flows are a common natural disaster in mountainous areas and often cause severe casualties and property loss. Debris-flow run-out effects analysis can provide an idea of the spatial risks posed to the downstream area of a debris flow, which is extremely important for local populations’ lives, disaster mitigation and planning the layout of economic construction. The objective of this study is to develop a new method to quantify debris flow run-out effects by combining debris flow simulation results and data for different types of land use within the inundated area. After a three-dimensional numerical simulation platform was established, the numerical simulation method was applied as a modeling tool to simulate the inundated areas and final buried depths under rainfalls with different return periods. The simulated result for flow depth under a 100-year return period rainfall event was validated based on field measurements. Finally, the debris-flow run-out effects under different return periods were analyzed by combining the simulation results and land use data. The proposed method can enhance the accuracy of debris-flow spatial risk assessment and has great value for application.

scholarly journals Classification and susceptibility assessment of debris flow based on a semi-quantitative method combining of the fuzzy C-means algorithm, factor analysis and efficacy coefficient

2020 ◽  
Author(s):  
Zhu Liang ◽  
Changming Wang ◽  
Songling Han ◽  
Kaleem Ullah Jan Khan ◽  
Yiao Liu
Keyword(s):  
Factor Analysis ◽  
Debris Flow ◽  
Human Activity ◽  
Land Use Planning ◽  
Debris Flows ◽  
Field Investigation ◽  
Matter Source ◽  
Susceptibility Analysis ◽  
Fuzzy C Means ◽  
Fuzzy C Means Algorithm

Abstract. The existence of debris flows not only destroys the facilities, but also seriously threatens human lives, especially in scenic areas. Therefore, the classification and susceptibility analysis of debris flow are particularly important. In this paper, 21 debris flow catchments located in Huangsongyu town ship, Pinggu District of Beijing, China were investigated. Besides field investigation, geographic information system, global positioning system and remote sensing technology were applied to determine the characteristics of debris flows. This article introduced clustering validity index to determine the clustering number, and the fuzzy C-means algorithm and factor analysis method were combined to classify 21 debris flow catchments in the study area. The results were divided into four types: scale-topography-human activity closely related, topography-human activity-matter source closely related, scale-matter source-geology closely related and topography-scale-matter source-human activity closely related debris flow. And 9 major factors screened from the classification result were selected for susceptibility analysis, using both the efficacy coefficient method and the combination weighting. Susceptibility results showed that the susceptibility of 2 debris flows catchments were high, 6 were moderate, and 13 were low. The assessment results were consistent with the field investigation. Finally, a comprehensive assessment including classification and susceptibility evaluation of debris flow was obtained, which was useful for risk mitigation and land use planning in the study area, and provided reference for the research on related issues in other areas.

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