COMPARATIVE STUDY AND INFLUENCING FACTORS OF LAND SURFACE EVAPOTRANSPIRATION IN THE MIDDLE ROUTE OF SOUTH-TO-NORTH WATER TRANSFER PROJECT

In this paper,the water source area of the Middle Route of South-to-North Water Transfer Project was chosen as the study area,and the meteorological data series of 9 meteorological stations and runoff data of Huangjiagang Hydrological Station have been collected.Based on these data,we have done comparative researches on several potential and actual evapotranspiration calculation methods with FAO Penman-Monteith equation and hydrological simulation via SWAT model as the benchmark,and also analyzed the influencing factors of land surface evapotranspiration.The conclusions are as follows.First of all,"evapotranspiration paradox" phenomenon exists in the Middle Route of South-to-North Water Transfer Project.Secondly,given that the results of Priestley-Taylor formula have a good linear correlation with those of FAO Penman-Monteith equation,we can build relevant equations to get evaporation information when there are less meteorological data series.Thirdly,the results of Fubaopu formula are close to the results of hydrological simulation.Besides,via correlation analysis between land surface evapotranspiration and meteorological factors,we have obtained that potential evapotranspiration have positive correlation with average temperature,diurnal temperature range,saturated vapor pressure,precipitation,net solar radiation and sunshine duration;Actual evapotranspiration have positive correlation with average temperature,diurnal temperature range,saturated vapor pressure,precipitation,net solar radiation,sunshine duration,and have negatively correlation with wind speed.The net solar radiation is a key factor affecting the land surface evapotranspiration.