An hybrid model of the MCDA for the GIS: Application to the localization of a site for the implantation of a dam

The choice of the localization of a urban infrastructure is a complex problem of the multicriterion decision aid (MCDA). To deal with this situation, several authors have demonstrated the interest of the association of the geographical information systems (GIS) and the MCDA. This association permits to manage the information of spatial reference, and at the same time to apply new methods of MCDA to select the best solutions. However, these analysis methods not only take into account the quantitative criteria, but also the qualitative and imprecise ones, linked to the environment, the regional development, and the socioeconomic impacts. To interpret these qualitative criteria correctly, it is necessary to represent them by precise values rather than by classic intervals. We propose in this paper, a hybrid model associating the multi-representation GIS (MRGIS), and the MCDA methods. Then, to facilitate the insertion of the qualitative criteria in our model, we propose an approach of data modelling based on the fuzzy logic, which allows us to represent all the information necessary to the decision making adequately. Finally, we will illustrate our subjects by an application of the localization of a site for the implantation of a dam.