Résumé
The joint research unit "HydroSciences Montpellier" (HSM) aims to study hydrological variability on the African continent. SIEREM, an environmental information system for water resources, has been developed at HSM. The POLLEN method was used to design and achieve this successful system. This method is adapted from the OMT (Object Modelling Technique) method, which is specific to the design of environmental information systems. The main part of the analysis technique consists of modelling the data, i.e. identifying the objects of the system, defining their structure and describing their relationships. The information system is then described according to the different services it has to fulfil. This permits one to define the processes asked for by the users and to provide a description of the functions and algorithms. The system is thus divided into sub-systems. Each one is described according to its interface, the piece of software implemented, the managed object classes and the services provided, and the relationships with the other sub-systems. The final result of this information system is a package of different software products. Depending on their rights and needs, the users get specific accesses to information. Each information type, such as a GIS layer or a rainfall chronicle, is managed in every different product of the system. The public can get metadata through the web site, a researcher in the laboratory can work with the data using the Orion software, etc.