A Preliminary Numerical Simulation Of The Thermodynamic Conditions Of Lugu Lake In Recent Years

Warming of the atmosphere and other climate change effects has strong impacts to the thermal stratification,and consequently effects the nutrient cycles,primary productivity and many other lake ecosystem features.In this research,the one-dimensional hydrodynamic model DYRESM and numerical code Lake Analyzer has been applied to the monomictic Lugu Lake,which is located in the southwest region of China.Lake stratification and other thermodynamic states has been simulated to provide the basis for revealing the effects of increasing air temperature on the lake ecosystems.The objectives of this study are: To calibrate and validate the model DYRESM in order to simulate the vertical thermal distribution in Lugu Lake and to establish a first hydrodynamic simulation run for the period 1954~2012;To describe the thermal structure by using Lake Analyzer.In the course of the modeling work,submodels are established or adjusted to simulate the missing meteorological radiation and hydrological data of forcing variables.The results showed as follows:1.The model has a better water temperature simulation on the lake surface and hypolimnion than metalimnion.When comparing simulated and measured water temperatures regarding the calibration period 2012~2013,small mean absolute errors(0.628~1.097 K)and root mean square errors(0.690~1.375 K),as well as high coefficients of determination(0.734~0.992)at all depth were observed.2.The model has long-term stability,and thus can be used to identify potential drawbacks of climate change(e.g.shifting duration of stratification,higher thermal stability,change of mixing depth)on the lake ecosystem by higher temperatures of water body and atmospheric layer above.3.Applying Lake Analyzer to analyze the water temperature data provided by DYRESM can get multiple indexes describing the lake thermal structure,but the index thickness of metalimnion has singular value 0 meter in the stratification period.In addition,this preliminary modelling provides various results making clear the the lacks of lake survey fulfilling and knowledge and the basis for coupled aquatic ecological models like CAEDYM.