Distributed hydrological models based on Remote Sensing (RS) and Geographical Information Systems (GIS) have become disciplinary frontiers of hydrological research, while developing GIS -based modeling systems are becoming more of an issue in GIS applied research. At present, the integration of hydrological models and GIS usually takes four approaches: hydrological modules embedded in a GIS, GIS functions embedded in a hydrological model, loose coupling of hydrological models and GIS and tight coupling of hydrological models and GIS. This paper introduces a distributed hydrological modeling system, namely, ArcTOP - a realization of full integration of a hydrological model within a GIS environment, which tightly couples a cell-based distributed model TOPKAPI with the Arc View GIS by using the macro language Avenue of Arc View.