System dynamics modeling of the influence of the TN/TP concentrations in socioeconomic water on NDVI in shallow lakes

It is critically important to investigate the influence of the total nitrogen (TN) and total phosphorus (TP) concentrations in socioeconomic water on the Normalized Difference Vegetation Index (NDVI) for the regional-scale utilization of water resources and ecosystem management in shallow lakes, which are easily disturbed by high-intensity human activities. In this study, we proposed a new system dynamics model with a coupled modeling structure to analyze a comprehensive influencing relationship between the NDVI and the concentrations of TN and TP from the socioeconomic water circulation during the growing season from 2000 to 2010 in Baiyangdian Lake, the largest shallow lake in northern China. The results show that, (1) there is a good comprehensive correlation between TN, TP and NDVI, with a correlation coefficient of 0.979; (2) compared to the industrial, domestic, and ecological water demand, the agricultural water demand exhibits the largest amount and the strongest ability in the creation of TN and TP, and the factor of agricultural wastewater affects the most. Therefore, the regulation of the agricultural wastewater would be the most efficient way to build a healthy environment for vegetative growth. This study contributes to the water resources planning and ecosystem management with the aim of improving both the water quality and the ecological functions in Baiyangdian Lake.