As required by European River Flood Occurrence & Total Risk Assessment System (EUROTAS), an Integrated Catchment Modeling system (ICM) and Decision Support System has been developed and integrated within ArcView to assist in making decisions on flood risk. The ICM is developed using an "open" system that can appropriately integrate currently available technology and components for catchment processing and management. ArcView and the Spatial Analyst extension was chosen as this "open" system because of its interface to databases, its visualization and spatial analysis tools, its capability to integrate vector and raster data, and its ability to link with external models.