It is necessary to understand the hydrological and pollutant cycle system of the watershed where a nature system element is intertwined to an artificial system element to promote the lake watershed management in the cooperation of labor. Additionally, we should have an objective tool which is appreciable of the effect of an each measure in the entire system.
We constructed a distributed pollutant flow model continuously to a distributed hydrological cycle model. And, we applied these models to the Lake Kasumigaura watershed which was a large area and general watershed. As a result, the pollutant flow process of the watershed was able to be understood for the unit of a standard grid cell. In addition, it was shown that the simulation tool which these constructed models cooperated was effective for the lake watershed management.