This paper introduces a novel visualization approach that can effectively facilitate the analysis, control, and refinement of dynamic environmental simulations on the World Wide Web. This approach overcomes drawbacks of current Internet Geographic Information System (GIS) technologies by providing an effective and efficient mechanism for two-way and sustained communication and synchronization between the visualization and the modeling processes. The critical aspect of this approach is the

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... ishment of a virtual environment on the Internet using the applet-servlet-socket architecture that supports real-time interactive and collaborative visualization of an environmental modeling process. In this virtual environment, the model residing in the simulation application server is fed with real-time rainfall data from a remote data server through a socket connection. The computational modeling and visualization can take place simultaneously on the application server and the client sides. As modeling computations proceed on the server, modeling results and outputs stream into the client side continuously. The client interface is updated with live 3D displays (not in the sense of predefined 3D animations provided by AVI or dynamic GIF files). Meanwhile, these 3D graphics can act as a support for further user interactions. A hydrological model, TOPMODEL, is implemented using the proposed web-based visualization environment to demonstrate the applicability of the proposed approach in facilitating environmental modeling and simulation.