Analysis of debris-flow recordings in an instrumented basin: confirmations and new findings

Abstract. On 24 August 2006, a debris flow took place in the Moscardo Torrent, a basin of the Eastern Italian Alps instrumented for debris-flow monitoring. The debris flow was recorded by two seismic networks located in the lower part of the basin and on the alluvial fan, respectively. The event was also recorded by a pair of ultrasonic sensors installed on the fan, close to the lower seismic network. The comparison between the different recordings outlines particular features of the August 2006 debris flow, different from that of events recorded in previous years. A typical debris-flow wave was observed at the upper seismic network, with a main front abruptly appearing in the torrent, followed by a gradual decrease of flow height. On the contrary, on the alluvial fan the wave displayed an irregular pattern, with low flow depth and the main peak occurring in the central part of the surge both in the seismic recording and in the hydrographs. Recorded data and field evidences indicate that the surge observed on the alluvial fan was not a debris flow, and probably consisted in a water surge laden with fine to medium-sized sediment. The change in shape and characteristics of the wave can be ascribed to the attenuation of the surge caused by the torrent control works implemented in the lower basin during the last years.

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Improvement of broadband seismic station installations at the Observatoire de Grenoble (OSUG) seismic network

Advances in Geosciences ◽

10.5194/adgeo-34-9-2013 ◽

2013 ◽

Vol 34 ◽

pp. 9-14 ◽

Cited By ~ 2

Author(s):

M. Langlais ◽

B. Vial ◽

O. Coutant

Keyword(s):

Seismic Station ◽

Seismic Network ◽

Protection System ◽

French Alps ◽

Long Period ◽

Seismic Recording ◽

Seismic Networks

Abstract. We describe in this paper different improvements that were brought to the installation of seismic broadband stations deployed by the Observatoire de Grenoble (OSUG) in the northern French Alps. This work was realized in the frame of a French-Italian ALCOTRA project (RISE), aimed at modernizing the broadband seismic networks across our common border. We had the opportunity with this project to improve some of our seismic recording sites, both in term of sensor installation quality, and in term of reliability. We detail in particular the thermal and barometric protection system that we designed and show its effect on the reduction of long period noise above 20 s.

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Deposition Prediction of Debris Flow Alluvial Fan Based on Experimental Study

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.518-523.4819 ◽

2012 ◽

Vol 518-523 ◽

pp. 4819-4822

Author(s):

Jin Feng Liu ◽

Shun Yang ◽

Guo Qiang Ou

Keyword(s):

Experimental Study ◽

Debris Flow ◽

Statistical Method ◽

Laboratory Experiments ◽

Empirical Models ◽

Alluvial Fan ◽

Disaster Prevention ◽

Average Accuracy ◽

Hazardous Area ◽

Debris Flow Disaster

The deposition prediction of debris flow hazardous area is very important for organizing and implementing debris flow disaster prevention and reduction. This paper selected the data base from laboratory experiments and applied the multiple regression statistical method to establish a series of empirical calculation models for delimiting the debris flow hazardous areas on the alluvial fan. The empirical models for predicting the maximum deposition length (Lc), the maximum deposition width (Bmax) and the maximum deposition thichness (Z0) under the condition of different debris flow volumes (V), densities (rm) and slopes of accumulation area (θd) were establised. And the verification results indicated that the established models can predict the debris flow hazards area with the average accuracy of 86%.

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Risk management on an alluvial fan: a case study of the 2008 debris-flow event at Villar Pellice (Piedmont, N-W Italy)

Natural Hazards and Earth System Science ◽

10.5194/nhess-10-999-2010 ◽

2010 ◽

Vol 10 (5) ◽

pp. 999-1008 ◽

Cited By ~ 17

Author(s):

M. Arattano ◽

R. Conte ◽

L. Franzi ◽

D. Giordan ◽

A. Lazzari ◽

...

Keyword(s):

Debris Flow ◽

Human Life ◽

Alluvial Fan ◽

Civil Protection ◽

Emergency Situations ◽

New Guidelines ◽

Personal Accounts ◽

Regional Authorities ◽

North Western

Abstract. In the Piedmont Region (North-Western Italy), the regional authorities manage debris flow risk by following the ideal sequence of steps that are generally pursued in land planning and civil protection activities. Complex procedures and methods are elaborated and widely discussed with politicians, economists and the general public. On the contrary, in emergency situations, civil protection agencies generally prefer the adoption of simple and flexible criteria. In this paper, a catastrophic debris flow event, that occurred in 2008 in Villar Pellice, is described in this perspective, after an analysis of the triggering rainfalls and of the effects on human life and properties. The availability of a series of personal accounts coming from people who witnessed the occurrences before, during and after the event has allowed us to analyse, in detail, the dynamics of the event. Thanks to these accounts, it has been possible to propose new guidelines for the planning of the emergency activities in areas that are potentially prone to similar impulsive phenomena.

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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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Debris flow monitoring in the French Alps

River Flow 2014 ◽

10.1201/b17133-211 ◽

2014 ◽

pp. 1589-1595

Author(s):

C Bel ◽

F Liébault ◽

H Bellot ◽

F Fontaine ◽

D Laigle ◽

...

Keyword(s):

Debris Flow ◽

French Alps ◽

Flow Monitoring

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Late Quaternary rapid talus dissection and debris flow deposition on an alluvial fan in Syria

CATENA ◽

10.1016/s0341-8162(03)00112-7 ◽

2004 ◽

Vol 55 (2) ◽

pp. 125-140 ◽

Cited By ~ 10

Author(s):

Takashi Oguchi ◽

Chiaki T. Oguchi

Keyword(s):

Debris Flow ◽

Late Quaternary ◽

Alluvial Fan

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Debris-flow monitoring and warning: Review and examples

Earth-Science Reviews ◽

10.1016/j.earscirev.2019.102981 ◽

2019 ◽

Vol 199 ◽

pp. 102981 ◽

Cited By ~ 10

Author(s):

Marcel Hürlimann ◽

Velio Coviello ◽

Coraline Bel ◽

Xiaojun Guo ◽

Matteo Berti ◽

...

Keyword(s):

Debris Flow ◽

Flow Monitoring

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Results and experiences gathered at the Rebaixader debris-flow monitoring site, Central Pyrenees, Spain

Landslides ◽

10.1007/s10346-013-0452-y ◽

2013 ◽

Vol 11 (6) ◽

pp. 939-953 ◽

Cited By ~ 41

Author(s):

M. Hürlimann ◽

C. Abancó ◽

J. Moya ◽

I. Vilajosana

Keyword(s):

Debris Flow ◽

Monitoring Site ◽

Flow Monitoring ◽

Central Pyrenees

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Effect of Combining Catalogs with Different Completeness

10.5194/egusphere-egu2020-1749 ◽

2020 ◽

Author(s):

Myunghyun Noh

Keyword(s):

Korean Peninsula ◽

North Korea ◽

Seismic Network ◽

The Other ◽

Earthquake Catalog ◽

Detection Capability ◽

Chi Square ◽

Earthquake Detection ◽

Seismic Networks ◽

Target Monitoring

In most seismic studies, we prefer the earthquake catalog that covers a larger region and/or a longer period. We usually combine two or more catalogs to achieve this goal. When combining catalogs, however, care must be taken because their completeness is not identical so that unexpected flaws may be caused.We tested the effect of combining inhomogeneous catalogs using the catalog of Korea Meteorological Administration (KMA). In fact, KMA provides a single catalog containing the earthquakes occurred in and around the whole Korean Peninsula. Like the other seismic networks, however, the configuration of the KMA seismic network is not uniform over its target monitoring region, so is the earthquake detection capability. The network is denser in the land than in the off-shore. Moreover, there are no seismic information available from North Korea. Based on these, we divided the KMA catalog into three sub-catalogs; SL, NL, and AO catalogs. The SL catalog contains the earthquakes occurred in the land of South Korea while the NL catalog contains those in the land of North Korea. The AO catalog contains all earthquakes occurred in the off-shore surrounding the peninsula.The completeness of a catalog is expressed in terms of mc, the minimum magnitude above which no earthquakes are missing. We used the Chi-square algorithm by Noh (2017) to estimate the mc. It turned out, as expected, that the mc of the SL is the smallest among the three. Those of NL and AO are comparable. The mc of the catalog combining the SL and AO is larger than those of individual catalogs before combining. The mc is largest when combining all the three. If one needs more complete catalog, he or she had better divide the catalog into smaller ones based on the spatiotemporal detectability of the seismic network. Or, one may combine several catalogs to cover a larger region or a longer period at the expense of catalog completeness.

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Outlining a stepwise, multi-parameter debris flow monitoring and warning system: an example of application in Aizi Valley, China

10.5194/egusphere-egu2020-4306 ◽

2020 ◽

Author(s):

Ningsheng Chen

Keyword(s):

Debris Flow ◽

Early Warning ◽

Pressure Sensors ◽

Warning System ◽

Point Of View ◽

Economic Point ◽

Flow Monitoring ◽

Vibration Sensors ◽

Wide Range ◽

Critical Rainfall

Abstract: In recent years, the increasing frequency of debris flow demands enhanced effectiveness and efficiency are essential not only from an economic point of view but are also considered as a frontline approach to alleviate hazards. Currently, the key issues are the imbalance between the limited lifespan of equipment, the relatively long period between the recurrences of such hazards, and the wide range of critical rainfall that trigger these disasters. This paper attempt to provide a stepwise multi-parameter debris flow warning system after taking into account the shortcomings observed in other warning systems. The whole system is divided into five stages. Different warning levels can be issued based on the critical rainfall thresholds. Monitoring starts when early warning is issued and it continues with debris flow near warning, movement warning and hazard warning stages. For early warning, historical archives of earthquake and drought are used to choose a debris flow susceptible site for further monitoring, Secondly, weather forecasts provide an alert of possible near warning. Hazardous precipitation, model calculation and debris flow initiation tests, pore pressure sensors and water content sensors are combined to check the critical rainfall and to publically announce a triggering warning. In the final two stages, equipment such as rainfall gauges, flow stage sensors, vibration sensors, low sound sensors and infrasound meters are used to assess movement processes and issue hazard warnings. In addition to these warnings, community-based knowledge and information is also obtained and discussed in detail. The proposed stepwise, multi-parameter debris flow monitoring and warning system has been applied in Aizi valley China which continuously monitors the debris flow activities.

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