The multidisciplinary programme of activities is built on a four-stage structure:
It is subdivided into 9 workpackages (WPs, see figure 1).
PHASE 1: DATA-COLLECTION AND ORGANISATION
The eight selected cases imply a complex risk situation, for which no reasonable stabilisation works can be achieved. The partners involved in the project have already some knowledge about the sites (some of them are very well known, while some others are in an initial stage of study), the data of which are already available but very dispersed (data banks, reports, publications…). In this way it will be relatively easy to collect a large amount of information without dispersion of energies.
A general scheme for data description has been created and compiled for each site (WP1). Each partner is then able to access to data, which can be managed in a homogeneous manner. The objective is also to check the reliability of the available data, to individuate which ones are to be considered.
Selected sites are summarised in table 1 and their location is shown in figure 2.
Figure 1. Graphical presentation of the project's components
PHASE 2: DEVELOPMENT OF RISK ASSESSMENT METHODOLOGIES
The purpose of Phase 2 is to provide the overall framework for risk assessment methodologies. Hazard analysis is the first step, and consists in the following activities:
As a result hazard analysis methods give the scenarios needed for the risk assessment. Several methodologies have been proposed in the past for the establishment of the hazard. Scenarios for the evolution of large landslides obtained through such methodologies provide different results, so it is difficult to express hazard in a unique way. It is therefore fundamental to compare and organise the different approaches so as to give to the EU all the elements necessary to practise an effective co-ordination role.
Within the project the following methodologies will be considered:
Figure 2. Location of the study sites
Table 1. Investigated landslide sites
Next step is the risk analysis, which includes:
Workpackage WP6 is dedicated to the state of the art in the evaluation of vulnerability and risk analysis. In order to quantify risk levels, three components will be analysed, related to the exposed objects, which may be influenced by landslides:
Finally, the results of phase 2 will be exemplified on the selected sites in the workpackage WP7, which will summarise the scenarios and give the risk evaluation for each site. Limits and applicability of the proposed risk assessment methodologies will be illustrated.
PHASE 3: APPLICATION TO THE MANAGEMENT
Phase 3 is related to the application of the developed methodologies to the management of endangered landslide zones (WP8). Mitigation strategies will be formulated in order to:
Corresponding types of actions are proposed in relation to the degree of urgency of the problem. For example, if a real crisis is expected within some weeks or even days, an evacuation plan must be prepared including large buffer zones and alarm systems must be placed to stop the traffic in case of a sudden failure. On the contrary, if the expected event is uncertain and might occur within months or years, alert systems must be installed and threshold values have to be determined for different types of possible landslide behaviours; it is also wise to determine alternative routes and to check if they present limitations or hindrances.
All the suggested actions related to safety criteria depend of course on the legal framework and on the powers that local or regional authorities have to solve critical situations or to manage minor or residual risks (i.e. limited risks that are induced by the later or final degradation of a failed slope, which can affect the exposed objects after years). This legal framework depends on the national or regional legislation, so that management policies have to be duly adapted. A catalogue of typical mitigation actions to face several hazard situations is also established.
Possible actions will be also proposed on the basis of the relevant economical conditions. Direct or indirect consequences are considered. For example a road leading to a major industrial site or tourist resort endangered by rockfalls will justify major protection investments to ensure a permanent transit even though the exposed infrastructures themselves are hardly affected by the stones falling on the road. The cost of works and labour force will also be a significant criterion for the selection of mitigation solutions.
The assessment of acceptable risks will also be based on the type and extent of hazard that might occur. A large sudden landslide causing the death of one hundred persons has not the same psychological impact as one hundred small rockfalls inducing each one victim; this effect, called the aversion factor, has to be included in the determination of mitigation strategies.
PHASE 4: DIFFUSION
The diffusion of risk management methodologies is the natural conclusion of the project (WP9). As regards this topic: