Simulation and Prediction of Water Quality in Huangjinxia Reservoir on Hanjiang River Based on MIKE21

Abstract

Huangjinxia Reservoir is a crucial source project in the Hanjiwei River diversion project. After the completion and operation of the reservoir, the water level reaches of the reservoir will rise, change the original water flow structure, greatly increase the submerged area of the original basin, and reduce the self-purification capacity of the water body. Under the existing pollution load conditions, the MIKE21 model is used to predict and calculate the concentrations of chemical oxygen demand, total phosphorus, and total nitrogen in the water body of the reservoir. The calculation results show that after the construction of Huangjinxia Reservoir, the concentrations of chemical oxygen demand and total nitrogen in the river reach the Class III water quality target requirements of the state, and the concentration of total phosphorus reaches the Class II water quality target requirements of the state. The overall water quality in the region is good. The possibility of water eutrophication is not high in the initial stage of reservoir construction and operation. However, due to the complex topography of some river channels (Jinshui River, Youshui River, etc.) and reservoir bay, poor water quality, poor water exchange performance, and the phenomenon of stem and leaf loss and death of flooded plants, the concentration of pollutants in some areas exceeds the standard. The long-term retention of pollutants does not rule out the possibility of water eutrophication. The water quality can be purified, and local water eutrophication can be controlled through rational use of the corresponding aquatic biological control technology.