Landslides are a serious problem for humans and infrastructure in many parts of Europe. Experts know to a certain degree which parts of the continent are most exposed to landslide hazard. Nevertheless, neither the geographical location of previous landslide events nor knowledge of locations with high landslide hazard necessarily point out the areas with highest landslide risk. In addition, landslides often occur unexpectedly and the decisions on where investments should be made to manage and mitigate future events are based on the need to demonstrate action and political will. The goal of this study was to undertake a uniform and objective analysis of landslide hazard and risk for Europe. Two independent models, an expert-based or heuristic and a statistical model (logistic regression), were developed to assess the landslide hazard. Both models are based on applying an appropriate combination of the parameters representing susceptibility factors (slope, lithology, soil moisture, vegetation cover and other-factors if available) and triggering factors (extreme precipitation and seismicity). The weights of different susceptibility and triggering factors are calibrated to the information available in landslide inventories and physical processes. The analysis is based on uniform gridded data for Europe with a pixel resolution of roughly 30 m 9 30 m. A validation of the two hazard models by organizations in Scotland, Italy, and Romania showed good agreement for shallow landslides and rockfalls, but the hazard models fail to cover areas with slow moving landslides. In general, the results from the two models agree well pointing out the same countries with the highest total and relative area exposed to landslides. Landslide risk was quantified by counting the number of exposed people and exposed kilometers of roads and railways in each country. This process was repeated for both models. The results show the highest relative exposure to landslides in small alpine countries such as Lichtenstein. In terms of total values on a national level, Italy scores highest in both the extent of exposed area and the number for exposed population. Again, results agree between the two models, but differences between the models are higher for the risk than for the hazard results. The analysis gives a good overview of the landslide hazard and risk hotspots in Europe and allows a simple ranking of areas where mitigation measures might be most effective.

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clearer understanding of the trends in the development of extreme weather. The studies are based on both historical data and available future scenarios (projections) from climate models. Compared to previous studies, we calculated changes in climate variables that are particularly important in relation to nature hazards. Overall, the analyses document an increase in frequency as well as intensity of both precipitation and wind. Results of projections show that the observed changes will continue throughout this century. We could also identify large regional differences, with some areas experiencing, e.g., a reduction in 30 the intensity of heavy rainfall events. However, most of the country will experience the opposite, i.e., both increased intensity and increased frequency of heavy precipitation. Our analyses show that at least 27 per cent of Norwegian roads and 31 per cent of railroads are exposed to rock fall and snow avalanches hazards. The project has also assessed relationships between different parameters that can affect the likelihood of debris flows. Variables such as terrain slope and size of watercourses are important, while local climate, which varies widely in Norway, determines threshold values for rainfall that can trigger debris 35 flows.Nat. Hazards Earth Syst. Sci. Discuss., https://doi

Road construction in rugged terrain and variable, partly harsh climate is challenging. Proper assessment of natural hazards at an early planning stage can give large cost savings and safer roads. In assessing natural hazards along 720 km of planned roads in Norway, a GIS based tool was developed to utilize publicly available data and dynamic runout models. The output is a definition of the most critical locations and serves to limit the extent of necessary field work. The Norwegian national susceptibility maps are generally conservative and using only these in the planning would give unrealistically high hazard levels. Various optimizing techniques were therefore implemented in the GIS tool and the outputs further calibrated against existing detailed hazard maps in selected locations and further validated during field work at the defined 'hotspots'. The field work comprised assessing return periods of unwanted events, probable closure time, and relevant mitigation measures, all within sets of pre-defined ranges of values. The following consequence evaluation quantified the indirect economic consequences of closed road and assessed the consequence for emergency preparedness qualitatively. Other consequences were not considered in the study. Climate change was considered and evaluated to increase the probability for flooding and debris flows, whereas the link between climate change and the other assessed hazards were considered too uncertain to impact on the risk estimates. Results of the study were communicated through an interactive map solution, with key results presented as fact sheets activated in the map for each risk section of the roads.

<p>On contract from a newly established road company in Norway, Nye Veier AS, a consortium of natural scientists and social scientists have carried out an early planning stage risk analysis from natural hazards for a series of new roads in Norway. An aim of the study was to establish methods and tools that the client could use relatively easily in their own premises and that could serve as a useful tool in design of the roads, including final selection of the route.</p><p>Firstly, a GIS-based tool was developed to perform a first screening of corridors around the proposed road. Hazards analysed included snow avalanches, rock falls, debris flows- and slides, landslides in sensitive ('quick') clays, floods, storm surges, strong winds and snow drift. In this phase we mainly used susceptibility maps and other data available on the internet. However, some of these are very conservative, and various methods of optimization have been performed in the analyses. After ground truthing of selected results of the GIS analyses, by field work, and by comparing with hazard maps based on previous field work, the GIS tool was installed in the client's premises and is currently being used by them.</p><p>Secondly, field work was carried out based on the results from the GIS screening. Identified higher-hazard segments were inspected, and key parameters, such as probability, length of closure in case of an event, type and cost of mitigation measure, and suggestions for potential re-routing were recorded in the field. Some of the hazard segments identified by the GIS analyses could also be called off from the field work. Results from the field work were standardized to the degree possible, e.g. in cost classes for mitigation measures, duration classes for closure time, etc.</p><p>Consequence and risk analyses were carried out based on the results of the combined GIS screening and field work. The consequences were estimated in two classes; a) Indirect Economic Consequence of a closed road, based on traffic density and type, the probable duration of closure, and the re-routing possibilities, and b) the consequences regarding emergency actions, i.e. the location of critical infrastructure (hospitals, fire stations, etc.) and the possibility for emergency vehicles to pass.</p><p>Climate change was considered mostly for the hazards that are directly connected to precipitation. For these a 'climate factor' was added based on the regional scenarios for 2100.</p><p>To ensure optimal communication of results to the client, the main delivery is a digital, GIS-based product. Hazard, consequence, and risk are marked in colours along the planned roads. By clicking on individual hazard segments, a comprehensive fact sheet appears with all available information, comments and numbers collected through the whole process. This includes also field comments, and a risk diagram, where also the estimated risk at year 2100 is indicated.</p><p>The work has been done in close interaction with the client, to ensure the most readily usable tool for them in present and future road projects.</p>