Aggregation of dispersed consequences for constructing criteria: the evaluation of flood risk reduction strategies

Construction of criteria is a major stage in the decision support process. This stage raises technical difficulties related to the presence of uncertainty and imprecision, qualitative consequences and multiple sub-consequences. In this paper, we are interested in the difficulties related to the construction of criteria which aggregate dispersed consequences. First, we give a general formulation of the problem of aggregating dispersed consequences. Then, in the context of a real application, we propose two original approaches for constructing criteria: the first one is based on an analytical aggregation of a quantitative dispersed consequence and the second approach is based on an aggregation by rules of a qualitative dispersed consequence. This application is part of a study which aims to compare various strategies of flood risk reduction for the river Loire.