[Method of Improving the Water Quality of Polluted Rivers Based on the MIKE11 Model]

In order to seek ways to improve the quality of polluted rivers, this study selected the heavily polluted Yinghe River in China for study, as there is a requirement to improve water quality from the Yangtze River to the Yinghe River. The permanganate index and ammonia nitrogen are the main pollutant targets for the Yinghe River. This study applies MIKE11 to set up a one-dimensional model of the hydrodynamics and water quality using a numerical simulation method to determine the optimal method for river water quality improvement. The simulation experiment tests the influence of factors, such as the supplementary water flow, replenishment water quality, water replenishment position, and method of water supply to improve the water quality. The simulation results indicate that water quality improvement can be simulated with the hydrodynamic module (HD) and the convective diffusion module (AD) combined with the rainfall runoff module (NAM) in the MIKE11 model. In practice, the option with the best replenishment effect is to use class Ⅲ at point 1 and to use class Ⅳ at points 2 and 3 when the supplementary water flow rate is 10% of the river bottom flow. The reduction in permanganate index and ammonia nitrogen was, respectively, 72.3% and 55.7%, and over 85% of the study area reached the standard of class Ⅳ water quality. This provides a new method for river pollution control.