The development of models using multiple modelling paradigms is necessary to formulate and study current problems in environmental science. To simplify the coupling of those models, a formal basis for a high-level specification of such models must be set-up. In this paper we propose a Discrete EVent System specification (DEVS) based modelling framework as a formal basis in environmental modelling. The formal framework ensures that models are reusable and interoperable components with well

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... d interfaces. Moreover, a wide variety of modelling paradigms can be expressed in the DEVS formalism. We are also extending the modelling paradigms that can be expressed in the DEVS framework with two techniques: Feedback-DEVS for the specification of supervised-learning models and Vector-DEVS for the specification of models in vector space. JDEVS is the java implementation of the framework. It enables discrete-event, general purpose, object-oriented, component based, GIS connected, collaborative, visual simulation model development and execution. A Feedback-DEVS neural-network model and a cellular infiltration model are described as experiments using JDEVS. Those models are later coupled to show the new modelling scenarios enabled by the use of a formal framework and the flexibility of the software. Hardware required: Any java enabled computer with 64 Mb of RAM and OpenGL or DirectX accelerated graphic card. Program Language: Java Program size: 5 MB Availability and cost: Free for non commercial use. Sample java applets and download from the project site: http://spe.univ-corse.fr/filippiweb/