Impact Of Landslides Along Road Network And Direct Cost Estimation: A Case Study In Marche Region, Central Italy

Abstract:

In November and December 2013, the Marche region (Central Italy) was hit by three severe, but not rare, meteorological events. The maximum value of the three days cumulative rainfall (499 mm) was recorded at the rain gauge of Pintura di Bolognola. The intense rainfall caused floods along the rivers and triggered numerous landslides, mostly located in the hilly and mountainous terrain of the region. The territory is crossed by a large number of roads connecting small rural settlements. After the events, the Regional Civil Protection Office requested to the Research Institute for the geo-hydrological Protection (IRPI-CNR) a technical support to evaluate the hazard condition for different sites affected by landslides. For an area of approximately 200 km², in the Municipalities of Acquasanta Terme and Roccafluvione, field surveys were carried out to identify the rainfall-induced landslides and to produce an event inventory map. More than 1,500 slope failures were mapped including earth flows, slide-earth flows, slides, rock-falls and complex slides. Field surveys were focused also to estimate qualitatively damages along the roads. Roads were classified in two classes: the main roads under the State responsibility and the secondary roads under the Municipality responsibility. The different types of damage were classified in three classes: i) aesthetic (minor), where the road functionality was not compromised; ii) functional (medium), where the functionality was compromised and iii) structural (severe) where roads are severely or completely damaged. Immediately after the event, the technicians of the Municipalities of Acquasanta Terme and Roccafluvione spent major efforts to partially restore the functionality of the secondary roads in order to guarantee the primary human needs. In the following ten days, they compiled a list of interventions, associated with the relative direct costs, aimed to the total restoration of the roads functionality. In collaboration with the technicians, we compared the estimate of the damages along the roads with the cost evaluation provided by the local authorities. The comparison allowed us to quantify the impact of the landslide events along the transportation infrastructures and to quantify the total direct cost for the secondary roads where the information was available.