Infrasound Array Analysis of Debris Flow Activity and Implication for Early Warning

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.

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Dendrogeomorphic reconstruction of past debris-flow activity using injured broad-leaved trees

Earth Surface Processes and Landforms ◽

10.1002/esp.1934 ◽

2010 ◽

pp. n/a-n/a ◽

Cited By ~ 4

Author(s):

Estelle Arbellay ◽

Markus Stoffel ◽

Michelle Bollschweiler

Keyword(s):

Debris Flow ◽

Flow Activity

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Application of a combined and automated monitoring and early warning system for debris flows at the Dawinbach

10.5194/egusphere-egu21-10280 ◽

2021 ◽

Author(s):

Tobias Schöffl ◽

Richard Koschuch ◽

Philipp Jocham ◽

Johannes Hübl

Keyword(s):

Debris Flow ◽

Early Warning ◽

Pulse Compression ◽

Mitigation Measures ◽

Heavy Rainfall Event ◽

Monitoring Site ◽

Traffic Lights ◽

The Road ◽

Pulse Compression Radar ◽

Monitoring And Early Warning

After a heavy rainfall event on August 31st, 2019, a debris flow at the Dawinbach in the municipality of Strengen (Tyrol, Austria) caused a blockage of the culvert below the provincial road B-316 and deposition in the residential area. The debris deposition raised up to 2 to 3 meters on the road and led to property damage to real estate. The total volume of the debris flow was approximately 15&#160;000 cubic meters.In order to control a further debris flow of this magnitude, the Austrian Service of Torrent and Avalanche Control started to construct mitigation measures. They include a channel relocation in order to significantly increase the channel crosssection. Hence the construction company STRABAG is also relocating the provincial road bridge.Since the risk for this road section and for the workers on site is particularly high during the construction period, a combined monitoring and early warning concept was developed and implemented by the BOKU, Vienna and the company IBTP Koschuch.The monitoring site consisting of a pulse compression radar and a pull rope system was installed 800m upstream from the fan. The combination of the two sensors now results in three major advantages.<ul><li>At sensor level, the system operates redundantly.</li> <li>A more reliable differentiation between increased discharge or debris flow is given.</li> <li>In the event of a false alarm, the system provides easier diagnosis and assignment of the fault.</li> </ul>Two events of increased runoff occurred during the deployment period. Both were successfully detected by the pulse compression radar. Here, the first event was used for threshold validation of the radar unit. Thus, an alarm could already be sent out automatically for the second one. The road is controlled by an integrated light signal system consisting of three traffic lights. A siren near the construction site can warn workers of an impending event by means of an acoustic signal. The reaction time after the alarm has been triggered is between 75 and 150 seconds, depending on the speed of the debris flow. The responsible authorities are informed by sending an SMS chain, which includes details about the type of process and the type of the activated triggering system.

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Application and analysis of debris-flow early warning system in Wenchuan earthquake-affected area

Natural Hazards and Earth System Science ◽

10.5194/nhess-16-483-2016 ◽

2016 ◽

Vol 16 (2) ◽

pp. 483-496 ◽

Cited By ~ 7

Author(s):

D. L. Liu ◽

S. J. Zhang ◽

H. J. Yang ◽

L. Q. Zhao ◽

Y. H. Jiang ◽

...

Keyword(s):

Debris Flow ◽

Wenchuan Earthquake ◽

Early Warning ◽

Early Warning System ◽

Prediction Accuracy ◽

Warning System ◽

Sichuan Province ◽

Affected Area ◽

The Wenchuan Earthquake ◽

New System

Abstract. The activities of debris flow (DF) in the Wenchuan earthquake-affected area significantly increased after the earthquake on 12 May 2008. The safety of the lives and property of local people is threatened by DFs. A physics-based early warning system (EWS) for DF forecasting was developed and applied in this earthquake area. This paper introduces an application of the system in the Wenchuan earthquake-affected area and analyzes the prediction results via a comparison to the DF events triggered by the strong rainfall events reported by the local government. The prediction accuracy and efficiency was first compared with a contribution-factor-based system currently used by the weather bureau of Sichuan province. The storm on 17 August 2012 was used as a case study for this comparison. The comparison shows that the false negative rate and false positive rate of the new system is, respectively, 19 and 21 % lower than the system based on the contribution factors. Consequently, the prediction accuracy is obviously higher than the system based on the contribution factors with a higher operational efficiency. On the invitation of the weather bureau of Sichuan province, the authors upgraded their prediction system of DF by using this new system before the monsoon of Wenchuan earthquake-affected area in 2013. Two prediction cases on 9 July 2013 and 10 July 2014 were chosen to further demonstrate that the new EWS has high stability, efficiency, and prediction accuracy.

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Early Warning of Long Channel and Post-controlled Debris-Flow Gully in Southwest China

Advancing Culture of Living with Landslides ◽

10.1007/978-3-319-53487-9_17 ◽

2017 ◽

pp. 155-160 ◽

Cited By ~ 1

Author(s):

Jian Huang

Keyword(s):

Debris Flow ◽

Early Warning ◽

Southwest China ◽

Long Channel

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Debris-flow activity in abandoned channels of the Manival torrent reconstructed with LiDAR and tree-ring data

Natural Hazards and Earth System Science ◽

10.5194/nhess-11-1247-2011 ◽

2011 ◽

Vol 11 (5) ◽

pp. 1247-1257 ◽

Cited By ~ 22

Author(s):

J. Lopez Saez ◽

C. Corona ◽

M. Stoffel ◽

A. Gotteland ◽

F. Berger ◽

...

Keyword(s):

Debris Flow ◽

Tree Ring ◽

Debris Flows ◽

Temporal Distribution ◽

Alluvial Fan ◽

Tree Ring Data ◽

Pine Trees ◽

Spatio Temporal ◽

Flow Activity ◽

Abandoned Channels

Abstract. Hydrogeomorphic processes are a major threat in many parts of the Alps, where they periodically damage infrastructure, disrupt transportation corridors or even cause loss of life. Nonetheless, past torrential activity and the analysis of areas affected during particular events remain often imprecise. It was therefore the purpose of this study to reconstruct spatio-temporal patterns of past debris-flow activity in abandoned channels on the forested cone of the Manival torrent (Massif de la Chartreuse, French Prealps). A Light Detecting and Ranging (LiDAR) generated Digital Elevation Model (DEM) was used to identify five abandoned channels and related depositional forms (lobes, lateral levees) in the proximal alluvial fan of the torrent. A total of 156 Scots pine trees (Pinus sylvestris L.) with clear signs of debris flow events was analyzed and growth disturbances (GD) assessed, such as callus tissue, the onset of compression wood or abrupt growth suppression. In total, 375 GD were identified in the tree-ring samples, pointing to 13 debris-flow events for the period 1931–2008. While debris flows appear to be very common at Manival, they have only rarely propagated outside the main channel over the past 80 years. Furthermore, analysis of the spatial distribution of disturbed trees contributed to the identification of four patterns of debris-flow routing and led to the determination of three preferential breakout locations. Finally, the results of this study demonstrate that the temporal distribution of debris flows did not exhibit significant variations since the beginning of the 20th century.

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