scholarly journals Dendrochronological Records of Debris Flow and Avalanche Activity in a Mid-Mountain Forest Zone (Eastern Sudetes — Central Europe)

2009 ◽  
Vol 34 (-1) ◽  
pp. 57-66 ◽  
Author(s):  
Ireneusz Malik ◽  
Piotr Owczarek
Keyword(s):  
Debris Flow ◽  
Central Europe ◽  
Debris Flows ◽  
Growing Season ◽  
Longitudinal Section ◽  
Mountain Forest ◽  
Snow Melt ◽  
Forest Zone ◽  
Geological Conditions

Dendrochronological Records of Debris Flow and Avalanche Activity in a Mid-Mountain Forest Zone (Eastern Sudetes — Central Europe)Dendrochronological methods were used to determine the frequency of debris flow/avalanche events in a forest zone. A debris flow and avalanche track located in the Eastern Sudetes Mountains (Central Europe) was analysed. The length of the youngest debris flow/avalanche track is about 750 m. Three distinct sections of the debris flow can be identified along the longitudinal section: niche, gully and tongue. The dendrochronological study shows that trees started growing on the margins of the debris flow between 1908 and 1963. Hence, debris flow and/or avalanche events occurred on this slope at the turn of the 19thand 20thcenturies. All trees collected from the tongue started growing between 1935 and 1964. However, a large debris flow event took place several years before, most probably during an extraordinary rainfall in June 1921. Following this event, several relatively large debris flows have occurred during the growing season, the strongest dendrochronologically confirmed events occurring in 1968, 1971-1972, 1991, 1997 and probably in 1977. Spring debris flow events induced by snow melt and/or avalanches have occurred in 1994 and 2004. The results suggest that with favourable geological conditions, debris flows can occur very frequently within entirely forested slopes.

scholarly journals Hydrometeorological threshold conditions for debris flow initiation in Norway

2012 ◽  
Vol 12 (10) ◽  
pp. 3059-3073 ◽  
Author(s):  
N. K. Meyer ◽  
A. V. Dyrrdal ◽  
R. Frauenfelder ◽  
B. Etzelmüller ◽  
F. Nadim
Keyword(s):  
Debris Flow ◽  
Water Supply ◽  
Debris Flows ◽  
Absolute Threshold ◽  
Exceedance Probability ◽  
Snow Melt ◽  
The West ◽  
Extreme Precipitation Events ◽  
The Absolute ◽  
Debris Flow Initiation

Abstract. Debris flows, triggered by extreme precipitation events and rapid snow melt, cause considerable damage to the Norwegian infrastructure every year. To define intensity-duration (ID) thresholds for debris flow initiation critical water supply conditions arising from intensive rainfall or snow melt were assessed on the basis of daily hydro-meteorological information for 502 documented debris flow events. Two threshold types were computed: one based on absolute ID relationships and one using ID relationships normalized by the local precipitation day normal (PDN). For each threshold type, minimum, medium and maximum threshold values were defined by fitting power law curves along the 10th, 50th and 90th percentiles of the data population. Depending on the duration of the event, the absolute threshold intensities needed for debris flow initiation vary between 15 and 107 mm day−1. Since the PDN changes locally, the normalized thresholds show spatial variations. Depending on location, duration and threshold level, the normalized threshold intensities vary between 6 and 250 mm day−1. The thresholds obtained were used for a frequency analysis of over-threshold events giving an estimation of the exceedance probability and thus potential for debris flow events in different parts of Norway. The absolute thresholds are most often exceeded along the west coast, while the normalized thresholds are most frequently exceeded on the west-facing slopes of the Norwegian mountain ranges. The minimum thresholds derived in this study are in the range of other thresholds obtained for regions with a climate comparable to Norway. Statistics reveal that the normalized threshold is more reliable than the absolute threshold as the former shows no spatial clustering of debris flows related to water supply events captured by the threshold.

Spatial-Temporal Assessment of Debris Flow Risk in the Ms8.0 Wenchuan Earthquake-Disturbed Area

2016 ◽  
Vol 11 (4) ◽  
pp. 720-731 ◽  
Author(s):  
Xin Yao ◽  
◽  
Lingjing Li ◽  
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Early Warning Systems ◽  
Rainfall Threshold ◽  
Significant Loss ◽  
Seismogenic Fault ◽  
Mountain Area ◽  
Disturbed Area ◽  
Geological Conditions

For 5 years (2009–2013) after the 2008 Ms8.0 Wenchuan earthquake, rainfall led to the transformation of unconsolidated co-seismic deposits into extensive and severe debris flows, causing significant loss of life and property. For debris flows in the earthquake-disturbed area, a few common concerns exist. What is their spatial-temporal distribution? What are the controlling factors? How much is the rainfall threshold for debris flows? What areas are more susceptible? Where suffered the most severe losses of life and property? Using debris flow characteristics, this study analyzes the relationships between seismic geological factors, geomorphologic factors, extreme rainfall, and debris flows in the 5 years following the earthquake, and draws the following conclusions. (1) There are regional differences in the rainfall threshold for generation of debris flows, and the annual maximum 72-hour accumulated rainfall for triggering a debris flow decreases from pre-seismic periods (135–325 mm) to post-seismic periods (75–160 mm) by 44.4–50.8% in study area. (2) Areas with high debris flow susceptibility and hazard are primarily controlled by seismic geological conditions. (3) The long-term risk of debris flows will fall to moderate, and the affected area will shrink to that around the seismogenic fault. The results of this study will help with meteorological early warning systems, deployment of disaster prevention and control projects, and reconstruction site selection in the post-seismic Longmen Mountain area.

scholarly journals Formation Conditions And Debris Flow Regime In Jiangjia Ravine, Yunnan, China – Applicability Of Russian Methodology

2022 ◽  
Author(s):  
Mingtao Ding ◽  
Aleksandr L. Shnyparkov ◽  
Pavel B. Grebennikov ◽  
Timur I. Khismatullin ◽  
Sergey A. Sokratov
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Climatic Conditions ◽  
Research Station ◽  
Normative Documents ◽  
Flow Formation ◽  
Geological Conditions ◽  
Wide Range ◽  
Formation Conditions ◽  
Former Ussr

The requirements of the debris flows’ parameters assessments vary from country to country. They are based on different theoretical and empirical constructions and are validated by data from different regions. This makes difficult comparison of the reported results on estimated debris flows activity and extent. The Russian normative documents for the debris flows’ parameters calculations are based on empirically-measured parameters in wide range of geological and climatic conditions at the territory of former USSR, but still not cover all the possible conditions of debris flow formation. An attempt was made to check applicability of the Russian empirical constructions for the conditions of the debris flows formation in Yunnan, China, where unique long-term dataset of debris flows characteristics is collected by the Dongchuan Debris Flow Observation and Research Station. The results show, that in general the accepted in Russia methodology of calculation of the parameters of debris flows of certain probability corresponded well to the observed in Dongchuan debris flows characteristics. Some discrepancies (in the average debris flow depth) can be explained by unknown exact return period of the actually observed debris flows. This allowed to conclude that the presently adopted empirical dependencies based on country-wide (USSR) empirical data can be extrapolated up to the monsoon climate and geological conditions of Yunnan province.

scholarly journals Learning Case Study of a Shallow-Water Model to Assess an Early-Warning System for Fast Alpine Muddy-Debris-Flow

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 750
Author(s):  
Antonio Pasculli ◽  
Jacopo Cinosi ◽  
Laura Turconi ◽  
Nicola Sciarra
Keyword(s):  
Debris Flow ◽  
Shallow Water ◽  
Early Warning ◽  
Debris Flows ◽  
Early Warning System ◽  
Warning System ◽  
Extreme Weather Events ◽  
Water Model ◽  
Computational Time ◽  
Processing Unit

The current climate change could lead to an intensification of extreme weather events, such as sudden floods and fast flowing debris flows. Accordingly, the availability of an early-warning device system, based on hydrological data and on both accurate and very fast running mathematical-numerical models, would be not only desirable, but also necessary in areas of particular hazard. To this purpose, the 2D Riemann–Godunov shallow-water approach, solved in parallel on a Graphical-Processing-Unit (GPU) (able to drastically reduce calculation time) and implemented with the RiverFlow2D code (version 2017), was selected as a possible tool to be applied within the Alpine contexts. Moreover, it was also necessary to identify a prototype of an actual rainfall monitoring network and an actual debris-flow event, beside the acquisition of an accurate numerical description of the topography. The Marderello’s basin (Alps, Turin, Italy), described by a 5 × 5 m Digital Terrain Model (DTM), equipped with five rain-gauges and one hydrometer and the muddy debris flow event that was monitored on 22 July 2016, were identified as a typical test case, well representative of mountain contexts and the phenomena under study. Several parametric analyses, also including selected infiltration modelling, were carried out in order to individuate the best numerical values fitting the measured data. Different rheological options, such as Coulomb-Turbulent-Yield and others, were tested. Moreover, some useful general suggestions, regarding the improvement of the adopted mathematical modelling, were acquired. The rapidity of the computational time due to the application of the GPU and the comparison between experimental data and numerical results, regarding both the arrival time and the height of the debris wave, clearly show that the selected approaches and methodology can be considered suitable and accurate tools to be included in an early-warning system, based at least on simple acoustic and/or light alarms that can allow rapid evacuation, for fast flowing debris flows.

scholarly journals Numerical Simulation of Non-Homogeneous Viscous Debris-Flows Based on the Smoothed Particle Hydrodynamics (SPH) Method

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2314 ◽  
Author(s):  
Shu Wang ◽  
Anping Shu ◽  
Matteo Rubinato ◽  
Mengyao Wang ◽  
Jiping Qin
Keyword(s):  
Debris Flow ◽  
Water Content ◽  
Smoothed Particle Hydrodynamics ◽  
Debris Flows ◽  
Sph Method ◽  
Particle Hydrodynamics ◽  
Sph Model ◽  
Smoothed Particle ◽  
The Impact ◽  
Kinetic And Potential Energies

Non-homogeneous viscous debris flows are characterized by high density, impact force and destructiveness, and the complexity of the materials they are made of. This has always made these flows challenging to simulate numerically, and to reproduce experimentally debris flow processes. In this study, the formation-movement process of non-homogeneous debris flow under three different soil configurations was simulated numerically by modifying the formulation of collision, friction, and yield stresses for the existing Smoothed Particle Hydrodynamics (SPH) method. The results obtained by applying this modification to the SPH model clearly demonstrated that the configuration where fine and coarse particles are fully mixed, with no specific layering, produces more fluctuations and instability of the debris flow. The kinetic and potential energies of the fluctuating particles calculated for each scenario have been shown to be affected by the water content by focusing on small local areas. Therefore, this study provides a better understanding and new insights regarding intermittent debris flows, and explains the impact of the water content on their formation and movement processes.

The Debris Flow Disaster Faster-Than-Early Forecast System (DFS) with Multi-Sensors Integrated Wireless Sensor Networks

2013 ◽  
Vol 347-350 ◽  
pp. 975-979
Author(s):  
Rong Zhao ◽  
Cai Hong Li ◽  
Yun Jian Tan ◽  
Jun Shi ◽  
Fu Qiang Mu ◽  
...  
Keyword(s):  
Wireless Sensor Networks ◽  
Sensor Networks ◽  
Debris Flow ◽  
Real Time ◽  
Debris Flows ◽  
Base Station ◽  
Base Stations ◽  
Wireless Sensor ◽  
Forecast System ◽  
Debris Flow Disaster

This paper presents a Debris Flow Disaster Faster-than-early Forecast System (DFS) with wireless sensor networks. Debris flows carrying saturated solid materials in water flowing downslope often cause severe damage to the lives and properties in their path. Faster-than-early or faster-than-real-time forecasts are imperative to save lives and reduce damage. This paper presents a novel multi-sensor networks for monitoring debris flows. The main idea is to let these sensors drift with the debris flow, to collect flow information as they move along, and to transmit the collected data to base stations in real time. The Raw data are sent to the cloud processing center from the base station. And the processed data and the video of the debris flow are display on the remote PC. The design of the system address many challenging issues, including cost, deployment efforts, and fast reaction.

Observations and Analyses of the 9 January 2018 Debris-Flow Disaster, Santa Barbara County, California

2021 ◽  
Vol 27 (1) ◽  
pp. 3-27
Author(s):  
Jeremy T. Lancaster ◽  
Brian J. Swanson ◽  
Stefani G. Lukashov ◽  
Nina S. Oakley ◽  
Jacob B. Lee ◽  
...  
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Extreme Rainfall ◽  
Atmospheric Conditions ◽  
Santa Barbara ◽  
Debris Removal ◽  
Fire Debris ◽  
Santa Barbara County ◽  
Coastal Land

ABSTRACT The post–Thomas Fire debris flows of 9 January 2018 killed 23 people, damaged 558 structures, and caused severe damage to infrastructure in Montecito and Carpinteria, CA. U.S. Highway 101 was closed for 13 days, significantly impacting transportation and commerce in the region. A narrow cold frontal rain band generated extreme rainfall rates within the western burn area, triggering runoff-driven debris flows that inundated 5.6 km2 of coastal land in eastern Santa Barbara County. Collectively, this series of debris flows is comparable in magnitude to the largest documented post-fire debris flows in the state and cost over a billion dollars in debris removal and damages to homes and infrastructure. This study summarizes observations and analyses on the extent and magnitude of inundation areas, debris-flow velocity and volume, and sources of debris-flow material on the south flank of the Santa Ynez Mountains. Additionally, we describe the atmospheric conditions that generated intense rainfall and use precipitation data to compare debris-flow source areas with spatially associated peak 15 minute rainfall amounts. We then couple the physical characterization of the event with a compilation of debris-flow damages to summarize economic impacts.

Reanalysis of Flash Floods and Debris Flows on two continents and their management strategies

2021 ◽  
Author(s):  
Juan Daniel Rios-Arboleda
Keyword(s):  
Risk Management ◽  
Developing Countries ◽  
South America ◽  
Debris Flow ◽  
Debris Flows ◽  
Large Scale ◽  
Management Strategies ◽  
Original Analysis ◽  
Risk Management Strategies ◽  
Latitudinal Patterns

<p>This research expands the original analysis of Baker and Costa (1987) including data from Europe and South America with the objective to understand if there are emerging latitudinal patterns. In addition, the threshold proposed by Zimmermann et al. (1997) it is evaluated with the data from tropical zones finding that this is a good predictor.</p><p>Mainly, recent Debris Flow occurred in South America are analyzed with the aim of identifying the best risk management strategies and their replicability for developing countries, particularly, the cases that have occurred in Colombia and Venezuela in the last 30 years are analyzed in order to compare management strategies and understand which are the most vulnerable areas to this phenomenon.</p><p>It is concluded that large-scale and multinational projects such as SED ALP are required in South America to better characterize events that have left multiple fatalities (sometimes hundreds of people) and better understand how to manage the risk on densely populated areas.</p><p>Finally, the use of amateur videos is proposed to characterize these events in nations with limited budgets for projects such as SED ALP, methodology that will be described extensively in later works.</p>

Granular effect on debris flow rheology

2021 ◽  
Author(s):  
Taiqiang Yang
Keyword(s):  
Shear Rate ◽  
Debris Flow ◽  
Debris Flows ◽  
Shear Thinning ◽  
Dynamical Equations ◽  
Real Rate ◽  
The Real ◽  
Jiangjia Gully ◽  
Material Sources ◽  
Surge Phenomena

<p>Debris flow is characterized by the multi-disperse grain composition and intergranular collision and friction, but the granular effects on rheology are often reduced to the volumetric concentration of solid (C<sub>v</sub>), almost ignoring the specific grain size distribution (GSD). In this study, small debris flows occurring in a tributary of Jiangjia Gully were taken as the material sources for rheology experiments. From the real flows we selected slurries with different C<sub>v</sub> and maximum grain sizes (D<sub>m</sub>) for rheological tests under shearing rate up to 40 (s<sup>-</sup><sup>1</sup>), which is usually the real rate for debris flows in natural conditions. The results indicate that the flows follow the Herschel-Bulkley (HB) rheology, with randomly changing consistency coefficient and relatively constant exponent of 0.45 on average. Only at high shear rate will the flow exhibit Bingham behavior. The HB rheology also reveals shear thinning behavior in surge phenomena observed in the field. Shear-thinning behavior is revealed by the viscosity-shear rate relationship: η<sub>a</sub>=pγ<sup>q</sup>, with the exponent (thinning index) dependent on shear rate. This greatly concerns the surge phenomena observed in field. Moreover, both the yield stress and the effective viscosity are found to be perfectly related to the scaling GSD parameters in power-law and exponential form, with nearly constant exponents independent of the shear rate(Figure 1). The rheology properties can be calculated from their relationships to GSD parameters (μ, D<sub>c</sub>), which in turn can be used to infer the HB rheology for the concerned flows and then build the dynamical equations(Figure 2). This implies the presence of some interlock between the fine and coarse grains. Finally the rheology model (general in HB form) can be completely determined by the GSD parameters. This study has for the first time proposed quantitative formulas for rheology incorporating GSD parameters, which is helpful for more accurate dynamic analysis of debris flow.</p>

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