Water temperature simulation of Lake Erhai based on EFDC model

Lake Erhai, which is in the early stage of eutrophication, is a deep plateau lake. There is no obvious thermocline in summer and autumn with unique vertical distribution of water temperature. To learn the changing rules of the hydrodynamic elements such as water level, water temperature and to analyze the effects possibly caused by them, the three-dimensional hydrodynamic model of Lake Erhai was established based on Environmental Fluid Dynamics Code (EFDC). The Latin Hypercube Sampling (LHS) and Standard Rank Regression (SRR) methods were employed to perform the water temperature parameters sensitivity analysis. It was found that the water temperature of the lake was sensitive to the change of the two parameters, including the proportion of fast wave in shortwave radiation (FSWRATF) and the coefficient of shortwave radiation rapidly attenuated in water (SWRATNF), while the effect of the coefficient of shortware radiation slowly attenuated in water (SWRATNS) was not significant. The water temperature spatial distribution mainly changed in the north-south direction, and obviously changed with seasons. Water temperature in Lake Erhai featured in decreasing from the north to the south in spring and summer, and north-south low, intermediate high in autumn and winter, which might be correlated with Lake Erhai Basin’s terrain and the location of the estuaries. The simulation results perfectly fit the weak str.pngication of water temperature in Lake Erhai, which was of great significance for explaining the vertical distribution of nutrient and algal bloom occurrence conditions there.