When creating risk maps the observed natural hazard is combined with the observed vulnerability. Here, the land use type represents vulnerability. Each region participated in the project has it's own land use plans. For the project tasks these plans were generalized and similar types of land use were grouped together. Single hazard maps combined with the land use maps produced risk maps for each hazard type.
Each combination of land use type and natural hazard were assigned a value from 1 to 4, 1 presenting the lowest risk and 4 the highest:
1 – Potentially low (geological) risk for the current / indicated type of land use, risk management not needed
2 – Potentially medium (geological) risk for the current / indicated type of land use, risk management recommended
3 – Potentially high (geological) risk for the current / indicated type of land use, risk management needed
4 – Potentially very high (geological) risk for the current / indicated type of land use, risk management compulsory
Assigning of values was done by using the Delphi method. The Delphi method was developed in the mid 1900's to give predictions on issues with uncertainties. The Delphi method can be described as a supporting tool in group work and communicating and solving complex issues having many sides. The method helps in finding a solution or common opinion for issues with many variables, or issues for which objective solutions cannot be found. Nowadays, the Delphi method is used in many kinds of risk analyses that combine social, economical and environmental viewpoints. (Olfert,A. Greiving, S. Batista, M.J.2006. Geological Survey of Finland, Special Paper 42, 125-151.)
In the CliPLivE project, the first round questionnaire was sent to selected experts from the project partner organizations. The experts were chosen so, that all the investigation areas were presented, and their backgrounds were from different fields of expertise. Questionnaire in this case was the risk matrix, where each recipient was asked to fill in a risk value 1-4 (one being the lowest risk and 4 the highest risk) for each combination of land use type and a hazard. Average value was calculated from these answers, and the experts were given the average value risk matrix to be seen, so that they were able to re-estimate the risks. Some small changes were done, and the second (final) risk matrix was compiled from the answers.
The outcome of the risk matrix is a risk classification for land use types and all types of hazard. The risk classification was used in assessing the areas vulnerable to certain hazard in corresponding region. Since this kind of evaluation is difficult to perform objectively by just one person, the Delphi method helps in adding objectivity into the classification. Different regions might also have different views on what functions and land use types are the most important for the local community.
In addition to single hazard risk maps integrated risk maps are produced. In an integrated map, all the single risk maps are combined so that the highest hazard class present at each location is shown.