AVTOP: a full integration of TOPMODEL into GIS

The integration of environmental models and Geographical Information Systems (GIS) usually takes two approaches: loose coupling and tight coupling. This paper, however, presents a full coupling approach within a GIS environment that is achieved by developing the existing hydrological models with the macro language of GIS. Such an approach makes it easy to capitalize on the GIS visualization and spatial analysis functions, thereby significantly supporting the dynamic simulation process of hydrological modelling. The full coupling approach is illustrated by AVTOP — a realization of TOPMODEL (TOPography-based hydrological MODEL) with the macro language Avenue of ArcView — within which all stages of model building are undertaken, from the initial parameter input and transformation of datasets, to the visualization of intermediate maps and the final presentation of results in various graphical formats in their geographic context. Furthermore, this approach provides a convenient and single environment for users to visually interact with the model, e.g. by adjusting parameters and observing the corresponding results simultaneously, which significantly facilitates users in exploratory data analysis and decision making in relation to the model applications.