Research On The Estimation Of Evapotranspiration From Different Underlying Surfaces In The Heihe River Basin Based On Complementary Principle

Evapotranspiration is the bond of water balance and energy balance on the land surface.The calculation of evapotranspiration is critical to the assessment of water resources in the basin and the feedback of land to the atmosphere.Due to the interaction between the land surface and the atmosphere,the temperature,humidity,and turbulence intensity of the near-surface atmosphere are affected by the evaporation of the underlying surface,and the potential evapotranspiration is also affected by the atmospheric conditions of the near-surface layer.Complementary theory of evapotranspiration takes into account the interaction between actual evapotranspiration and potential evapotranspiration.The actual evapotranspiration can be calculated by conventional meteorological data,which provides an effective method for calculating the actual evapotranspiration.Therefore,it is of great scientific and practical significance to study the complementary theoretical evapotranspiration calculation model.This paper selects the Heihe River Basin with prominent water resources problems as the research area based on the acquisition of ground data and the need for complementary model research,Aorou Super Station,Daman Super Station,Shenshawo Desert Station and Bajitan Gobi Station Observed data,analyzed the actual evapotranspiration and potential evapotranspiration time changes and influencing factors,found that due to differences in geographical location,ground wetness,radiant energy,the relationship between potential evapotranspiration and actual evapotranspiration on different underlying surfaces shows different characteristics,but the complementary relationship between potential evapotranspiration and actual evapotranspiration can be verified.In this paper,we use the typical AA model and the two widely used complementary models:power function model and polynomial model,and use the dimensionless analysis method to transform the different complementary models into comparable forms,and make a theoretical analysis and comparison of the three models.We compared the calculation accuracy of three models under different underlying surfaces on the daily scale and the monthly scale,and discussed the applicability of the three models,the study found that Arou grassland station has the best adaptability to the model,The function model has better simulation effect on arid regions than AA model and polynomial model.Study also found that the parameters in the evapotranspiration formula of humid environment indicate that evapotranspiration is affected by advection and turbulence,and should not be a fixed value.We also compare and analyze the three correction methods,considering the regionalcharacteristics and the principle of complementary model,and apply them to the complementary evapotranspiration model,The results show that after optimization,The estimation accuracy of the four station evaporation complementary models for the actual evapotranspiration is improved,and the estimation error of the large full station model is obviously reduced.For the model,both the AA model and the polynomial model have reduced errors in the calculation of actual evapotranspiration.After month-to-month optimization,the estimation accuracy of the model is improved.The research results of this paper have reference significance for water resources management in Heihe River Basin.