MIKE 11 model-based water quality model as a tool for the evaluation of water quality management plans

Water quality models are important tools to test the effectiveness of alternative management plans on the water quality of water bodies. The main aim of this study was to develop and demonstrate use of a water quality model as a tool for evaluation of alternative water management scenarios for the river basin of Beijing, China. Considering Lao Hewan river landscape water circulation patterns and water quality protection programme, hydrodynamic module, structure operation module, advection/dispersion module and ECOlab module in the MIKE 11 model system, the circulating water drainage system and water quality model have been developed for water protection measures. Modelled results indicate the simulated biochemical oxygen demand, chemical oxygen demand, ammonia and total phosphorus concentration evolve in a general increasing trend for the first scenario since there are no water purification measures taken in this scenario; for the second scenario, the simulated water quality showed a slight decreasing trend in both sites, and better than that of scenario I due to considering the water circulation with a volume of 40,000 m³/d in both sites and the purification function of the wetlands of the Centre Lake. Simulated concentrations of pollutants in scenario III are lower than in scenarios I and II, due to the strengthened purification measures (horizontal subsurface flow wetland and surface flow wetland) implemented.