The severe Mediterranean storm occurred on 25 October 2011 triggered several shallow landslides in the Cinque Terre area (eastern Liguria, Italy) that disrupted transportation routes causing significant direct and indirect economic losses. In the Vernazza catchment the high-intensity rainfall event (472 mm/6h at Brugnato, Vara valley, and 349mm/6h at Monterosso, Cinque Terre) generated more than 500 shallow landslides and all provincial roads connecting the village of Vernazza to the inland were closed due to severe damages. The reparation works on roads has been estimated at more than 10 million Euros. Indirect economic losses related to road closures are unknown but, although difficult to estimate, are likely to be higher than the direct losses, being this area a very famous tourist resort. A quantitative procedure has been applied for estimating shallow-landslide risk along the road network of Vernazza catchment in case a similar event occurs again. Firstly, a landslide hazard model has been produced analyzing statistically the spatial relationship between the landslide-event inventory and several conditioning factors. Secondly, the potential economic losses on roads have been estimated defining damage scenarios. The risk estimation has been calculated by combining landslide occurrence probability and expected losses on every road stretch. Additionally, the following aspects of the risk estimation, assessment and management have been analyzed simulating different solutions for hazard mitigation: (1) Impact of land use changes on landslide hazard and risk; (2) Identification of suitable engineering mitigation measures to reduce possible future economic losses; (3) Cost-effectiveness of proposed solutions. The presented method will be adapted to analyze other elements at risk in the study area to provide decision makers with the basis to select the most adequate mitigation solution considering both economic and societal factors.
Evaluation of mitigation measures to reduce shallow-landslide hazard induced by extreme rainfall events: analysis of the road network in the Vernazza catchment (Cinque Terre, Italy)
BRANDOLINI, PIERLUIGI;CEVASCO, ANDREA;
2013-01-01
Abstract
The severe Mediterranean storm occurred on 25 October 2011 triggered several shallow landslides in the Cinque Terre area (eastern Liguria, Italy) that disrupted transportation routes causing significant direct and indirect economic losses. In the Vernazza catchment the high-intensity rainfall event (472 mm/6h at Brugnato, Vara valley, and 349mm/6h at Monterosso, Cinque Terre) generated more than 500 shallow landslides and all provincial roads connecting the village of Vernazza to the inland were closed due to severe damages. The reparation works on roads has been estimated at more than 10 million Euros. Indirect economic losses related to road closures are unknown but, although difficult to estimate, are likely to be higher than the direct losses, being this area a very famous tourist resort. A quantitative procedure has been applied for estimating shallow-landslide risk along the road network of Vernazza catchment in case a similar event occurs again. Firstly, a landslide hazard model has been produced analyzing statistically the spatial relationship between the landslide-event inventory and several conditioning factors. Secondly, the potential economic losses on roads have been estimated defining damage scenarios. The risk estimation has been calculated by combining landslide occurrence probability and expected losses on every road stretch. Additionally, the following aspects of the risk estimation, assessment and management have been analyzed simulating different solutions for hazard mitigation: (1) Impact of land use changes on landslide hazard and risk; (2) Identification of suitable engineering mitigation measures to reduce possible future economic losses; (3) Cost-effectiveness of proposed solutions. The presented method will be adapted to analyze other elements at risk in the study area to provide decision makers with the basis to select the most adequate mitigation solution considering both economic and societal factors.
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