Simulation on TN and TP Distribution of Sediment in Liaohe Estuary National Wetland Park Using MIKE21-Coupling Model

Abstract

A hydrodynamic-water quality model was established using MIKE21 to analyze the distribution of total nitrogen (TN) and total phosphorus (TP) in the wetland sediments of Liaohe Estuary National Wetland Park. The purpose of this model is to investigate the spatial and temporal variation patterns in wetland sediments and the distribution of pollutant contents. The research determines the applicability of this model in accurately predicting these patterns. The simulated contour map of the water quality concentration displays significant variation characteristics and reflects the actual concentration of pollutants in the wetland sediment of the Liaohe Estuary, proving the coupled model to be reasonable and accurate. The water quality simulation results indicate that water flowing through the wetland aids in purifying pollutants in the sediment, and the purification effect is more significant during the flood season. The MIKE21 model’s treatment reveals that the content of TN in wetland sediments decreases from southwest to northeast in the surface layer, following the flow direction of surface water. As the depth increases, the content of TN also decreases, with the bottom layer showing a decrease from southwest to northeast. The TP in wetland sediments receives surface water runoff and diffuses from upstream to downstream. The content of TP gradually decreases with increasing depth.