Historical Simulations of Nutrient Sedimentary and Transportb Changes in Honghu Lake Basin

Key words: 
• naturalagricultural environment /
• nutrient sedimentation /
• TN and TP transportations /
• simulations /
• Honghu Lake Basin /

Abstract: A catchment's nutrient model SWAT was used in this paper to examine changes in the nutrient sedimentation and transportation in a hundredyear time scale, and Hong Lake Basin, located in the middle reach of Changjiang River was chosen as the study area. Boundary condition in the simulations is prescribed in a preindustrial time mode in order to evaluate a naturalagricultural forced nutrient changes in the Hong Lake Basin one hundred years ago. Total nitrogen (TN) and total phosphorus (TP) in the main channel transported into the lake were simulated in two periods of flood season (summer) and nonflood season (spring, fall and winter) in running 200 model years respectively. Results show the modeling can catch basic features of the basin nutrient transportations and changes. The TN and TP concentrations show significant seasonal changes, and annul mean concentration can be compared well with nutrient concentrations transformed from sediment cores of Hong Lake that records were 137Csdated to ca 100 year ago. Time series in the 200yr simulation shows different trends in TN and TP concentration changes. There are obvious differences spatially in the input and output subbasins. The SWAT model has provided an effective tool to evaluate how nutrient production and changes in natural environmental system of the 200 years in the Hong Lake Basin.