Analysis Of Estimating And Driving Force Of Actual Evapotranspiration In Watershed Based On Generalized Complementary Relationship

Evapotranspiration plays a key role in climate change and maintaining surface energy balance.Accurate estimation of actual evapotranspiration is conducive to improving the utilization rate of water resources and alleviating the pressure of ecological environment.Based on meteorological elements,remote sensing and basic geographic information data,this paper studies and analyses the principle of generalized complementary correlation.Using water balance equation to calibrate parameters and verify the results of the model simulating,it obtains the suitable estimating actual evapotranspiration(E_Ta mmodel for Chinass specific situation.On this basis,we use the model to simulate the actual evapotranspiration of land surface in China from 1961 to 2010,and then analyze its spatial and temporal distribution characteristics.Finally,we deeply analyze the sources of actual evapotranspiration in China,and explore the correlation between actual evapotranspiration and radiation energy and aerodynamics.The main conclusions are as follows:Using the basic form and quadratic form of Brutsaert model and Szilagyi model,it founds that the accuracy of the four models is different after revising the parameters of the four models through the water balance equation.The best simulation effect is the basic form of Brutsaert model,which is also the most suitable one for estimating the actual evapotranspiration in China.TheE_Ta of China in the past 50 years increases slowly in timeand decreases from southeast to northwest in space.E_Ta decreases with the increase of latitude,and the farther away from the ocean.Similar to the climate zoning,E_Ta of wet area is highest,which of arid area is lowest.Lastly,in terms of watershed division,the Songhua River basin has the most significant upward trend,and the Southeast Zhuhe River basin has the most obvious downward trend.E_Ta of the Pearl River basin is the highest,which of the Northwest Zhuhe River basin is smallest.Based on the analysis of the sources of actual evapotranspiration changes in the whole and ten first-level basins of China,it shows that the evapotranspiration increases with the increasing of the radiation energy term and decreasing of the aerodynamic term.It also founds that the radiation energy term is the main reason for the change.