Numerical Simulation Of Heavy Metal Migration Characteristics In Reservoir Based On MIKE21 Model

With the rapid development of China's economy,the progress of industry and agriculture has brought great benefits to people's life,but it also has a negative impact on the ecological environment.A large number of heavy metal elements produced in industry and agriculture enter soil and water,because of its characteristics of easy accumulation,hard to degrade,long incubation period,great harm,etc.The problem of metal pollution is becoming more and more prominent.Reservoirs are important water resources development and utilization projects and play a key role in flood control,power generation,navigation,water supply and irrigation.However,in recent years,heavy metal pollution problems have occurred repeatedly and are extremely difficult to control,causing serious damage to the ecological environment of reservoirs.Therefore,it is very urgent to carry out heavy metal remediation in reservoirs.In the treatment of heavy metals in reservoirs,the migration and transformation of heavy metals in the water body must be fully understood.However,the transport of heavy metals in the water,adsorption and desorption,precipitation and dissolution are closely related to the conditions of soil,rock,and sediments,and their processes are closely related.It is very complicated.Therefore,it is very necessary to carry out research on the migration characteristics of heavy metal pollution in reservoirs.This paper focuses on the migration of heavy metals before and after reservoir storage,and takes the proposed construction of the Zongtongka Water Control Project as the research object.Based on the hydrodynamic modules and heavy metal modules of the MIKE 21 model,A two-dimensional mathematical model for migration and transformation of heavy metals in the reservoir area was established on the basis of consider release of heavy metal contaminants in flooded soils,rocks and sediments after impoundment,migration and diffusion of heavy metals in water and sediments,suspension sedimentation and adsorption analysis.In the heavy metal module,the control equations of the migration process of heavy metals with water and suspended matter are merged into the control equation of the total heavy metal migration process.In the heavy metal module,the control equations for the migration process of heavy metals with water and suspended matter are merged into the total heavy metal migration process control equations,and the release formulas for characteristic pollutants in flooded rocks,soil,and sediments are added.Discrete equations using the finite volume method and quadratic Runge-Kutta methods for integrating the ECO Lab Ordinary Differential Equations.Using the established mathematical model to study the spatial-temporal distribution characteristics and migration characteristics of heavy metal pollutants in the water storage process of Zongtongka Water Control Project,comparative analysis of changes in heavy metal concentrations during storage of reservoirs to normal water levels in different typical years(rich,normal,and dry years).The results of the study showed that the smaller the upstream incoming water flow,the lower the concentration of heavy metals in the water when the water storage is completed,and the higher the peak metal concentration of water in the water storage process.