Impact of the second phase of the eastern route of South-to-North water diversion project on distribution of nitrogen and phosphorus in Hongze Lake

Abstract

Nitrogen (N) and phosphorus (P) concentrations are the fundamental factors affecting the nutrient status and productivity of lakes, and extrinsic inputs of N and P primarily cause eutrophication of lakes. In this essay, taking Hongze Lake as the study area, a two-dimensional hydrodynamic and water quality mathematical model of Hongze Lake was constructed, and based on calibration and verification of parameters, numerical simulation was performed on the changes in N and P concentrations in this lake after water transfer. The study results exhibited that before and after project construction, the absolute values of rates of changes in the annual average concentrations of Ammonia nitrogen (NH4+-N), Total phosphorus (TP), Total nitrogen (TN), and Permanganate index(CODMn) in Hongze Lake were all lower than 20%, which demonstrates marginal changes in the annual average concentrations. By analyzing the seasonal and spatial distribution characteristics of the concentrations of nitrogen, phosphorus and other pollutants in the lake area before and after the project operation, it is found that the main reasons that affect the water quality change in the lake area after the project operation are the newly added water transfer volume, water transfer location and water transfer quality.

Impact on urban river water quality and pollution control of water environmental management projects based on SMS-Mike21 coupled simulation

“…From a spatial point of view, the water quality in the upper reaches of the river is superior to that in the lower reaches, attributed to the dilution effect of the water. Besides, due to significant pollutant discharges, localized increases in pollutant concentrations were observed near the three outlets 47 .…”