Spatiotemporal Distribution of Nutrients and Chlorophyll-a in Dongping Lake Based on Delft3D Modeling
To investigate the spatiotemporal distribution of nutrients and chlorophyll-a (Chl-a) in Dongping Lake, a coupled hydrodynamic-water quality-ecological model was developed using Delft3D. The model simulated total nitrogen (TN), nitrate nitrogen (NO3-N), ammonia nitrogen (NH4-N), total phosphorus (TP), soluble reactive phosphorus (SRP), and Chl-a. After validation, the model systematically analyzed the spatiotemporal patterns and influencing factors, revealing nitrogen and phosphorus transformation pathways. Results showed three temporal phases: relatively stable concentrations from January to April, significant fluctuations from May to August, and gradual stabilization from September to December, with peak timing varying among indicators. Spatially, concentrations were generally higher in the south and lower in the north, but NH4-N, TP, and Chl-a exhibited reverse patterns (higher in north) during certain periods. External inputs, primarily from the Dawen River, dominated the overall distribution, while water temperature, dissolved oxygen, and hydrodynamic conditions further modulated internal variability. Nitrogen and phosphorus showed distinct fates: nitrogen was primarily removed via denitrification and anammox, whereas phosphorus tended to transform into particulate forms and remained in the lake for extended periods. These findings provide scientific support for precise water quality management in Dongping Lake.