Three-dimensional Temperature Model Research Of Lakes Based On The Improved Solar Radiation Heat Flux

Lakes,as the important freshwater reserve in inland areas,with the global climate change and human social activities,the lake water environment is seriously threatened.There are many factors that affect the water temperature,such as solar radiation,air temperature,relative humidity,cloud cover and wind speed.Solar radiation is the main heat source of water,and the water temperature is largely determined by solar radiation.Presently in most of lake water temperature models,the calculation method of solar radiation heat flux ignores that attenuation of solar radiation is different in different depth of water.The traditional method uses unified attenuation coefficient,and the water absorptivity is regarded as constant value.Some even ignore the water absorption rate directly.Aiming at the shortcomings of traditional method,this paper considers the water absorption and light attenuation coefficient,uses two different attenuation coefficient to quantify surface attenuation and deep attenuation.This paper points out that due to the difference of substance concentration in different lakes and different absorption coefficient of sunlight,the water absorption rate is not the same for all lakes.Finally,an improved calculation model of solar radiation heat flux is established.Firstly,researches the water heat exchange mechanism.Then through correlation analysis,we can identify the main meteorological factors affecting the water temperature in Donghu Lake.After that,uses C# language to develop program,and the operator splitting method to discrete the governing equations.Taking Donghu Lake as the research object,this paper gives a brief introduction to the distribution of water temperature in Donghu Lake,couples the improved solar radiation heat flux calculation model with the three-dimensional water temperature model,explores the uncertainty of the model parameters,simulates the horizontal and vertical distribution of water temperature,and analyzes the results of traditional methods and improved methods.The result shows that the simulation of the improved method is more detailed,and describes the difference of water temperature in different water layers.