DEBRIS-FLOW PROTECTION IN RECURRENT AREAS OF THE PYRENEES. EXPERIENCE OF THE VX SYSTEMS FROM OUTPUT RESULTS COLLECTED IN THE PIONEER MONITORING STATION IN SPAIN — IJEGE
 
 
You are here: Focus and scope Issues from 2005 to 2017 5th International Conference on Debris-Flow Hazards "Mitigation, Mechanics, Prediction and Assessment" Topic 9 - Debris-flow Countermeasures DEBRIS-FLOW PROTECTION IN RECURRENT AREAS OF THE PYRENEES. EXPERIENCE OF THE VX SYSTEMS FROM OUTPUT RESULTS COLLECTED IN THE PIONEER MONITORING STATION IN SPAIN
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DEBRIS-FLOW PROTECTION IN RECURRENT AREAS OF THE PYRENEES. EXPERIENCE OF THE VX SYSTEMS FROM OUTPUT RESULTS COLLECTED IN THE PIONEER MONITORING STATION IN SPAIN



Abstract:
The south eastern part of the Pyrenees is currently affected by debris flow phenomena. The combination of Mediterranean and Continental climate, the orography (up to altitudes of 3300 m), the glacial materials on the slope’s surface, the lack of arboreal coverage compared with the rest of the Pyrenees, the high seismicity and the increasing human occupation in the valleys, put altogether is a very dangerous combination and makes the debris flow management extremely difficult. The first monitoring system for debris flow phenomena was installed in Spain in 2005. The aim was to monitor the debris flow phenomenon’s behaviour in the Erill basin, in the north of the province of Lerida. The Erill location in the south of the Pyrenees is one of the places where the debris flow phenomenon is common and where, apart from the possible magnitude of any event, the likely affected area includes the urban area of the Erill village. Remote controlled autonomous monitoring equipment was installed in this location. It was composed of an automatic meteorological station, a set of geophones to activate the measuring and recording systems, a VX160 barrier protection system, monitored with load-cells, a camera and digital recording equipment, all connected to a data logger with a GSM modem. The information provided by the detection system was completed during 2009 by a topographic schema, created by the LIDAR system, of the basin that generates the debris flow. The objective was to try to detect, before the event, the specific deformations that cause the debris flow. We have collected information related with different events of small volume (< 100m3) that had a direct correlation with the intensive rainfall in the basin. During 2009, based on the knowledge gained from the behaviour of the Erill basin, the first applications and designs of VX160 systems were created for other sites. The work done in the Portainé gully is an example of this. In 2008, this zone was affected by a debris flow of more than 20.000 m3. The protection system that was installed was made up of 9 VX160 transversal protection lines, with a total retention capacity of approx. 25.000 m3. Three months after they were installed, the fences were completely full as a result of two events caused by summer storms. The installed solution costs 40% less than the traditional check dam solution. This paper shows the importance of the research, of these specific phenomena in the Pyrenees, to the development of protection technology. The autonomous measurement equipment, together with the tested protection system can be applied, with the corresponding reduction in costs, to civil protection and hydrological correction situations in urban and suburban zones where debris flow is a recurring phenomenon.

Authors:
Roberto Luis-Fonseca - Geobrugg Ibérica S.A.U, Spain
Carles Raïmat - Geobrugg Ibérica S.A.U, Spain
Marcel Hürlimann - Department of Geotechnical Engineering and Geosciences, Technical University of Catalonia, Spain
Claudia Abancó - Department of Geotechnical Engineering and Geosciences, Technical University of Catalonia, Spain
José Moya - Department of Geotechnical Engineering and Geosciences, Technical University of Catalonia, Spain
Jesús Fernández - Forestal Catalana S.A., Spain
Keywords
Monitoring, hydrological correction, debris-flow protection, Pyrenees, ring net.
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