Hydrological and Material Cycle Simulation in Lake Biwa Basin Coupling Models about Land, Lake Flow, and Lake Ecosystem

Lake Biwa is the largest freshwater body in Japan and its water quality (e.g. COD(Mn)) is worsening since 1985 despite various pollution prevention measures. In order to implement more effective measures, “Lake Biwa Basin Integrated Management Model (LBIM)”, which can simulate hydrological and material cycle situation in Lake Biwa Basin, was constructed. LBIM consists of three component models; the land model, the lake flow model, and the lake ecological model. As a result of the calculation of water quality and quantity in Lake Biwa Basin by applying LBIM, those were simulated well including the difference between areas. In addition, the effect of some measures to the lake water quality was evaluated.