Our research focuses on the management of information system evolution. To answer these issues, we have expanded the Information System Urbanism methodology to specify the "Information System Organisational Urbanism". This methodology consists in three complementary steps. The cadastral urbanism formalizes the knowledge on the existing information system. It provides all the necessary models in this perspective. The prospective urbanism suggests defining the target of the information system, in coherence with the firm's strategic orientations and the existing system. To provide a structured and flexible vision of the information system, we present an innovative formalisation of dependency between enterprise processes. The decision support system developed uses a clustering method, in order to generate interesting sets of processes. We suggest several diagnosis of the information system, based on the use of the cluster maps to improve the management of information systems transformations.
