| Surface evapotranspiration is an important link in the process of hydrological cycle.It has important research significance and value for the study of climate,hydrology,agriculture and other disciplines.Traditional evapotranspiration calculation models are mostly based on "points".The development of remote sensing technology makes it possible to retrieve regional evapotranspiration because of its convenient and fast access to ground information.SEBAL model is a kind of evapotranspiration inversion model based on remote sensing image data,which has been developed in recent years and has good application effect.Using remote sensing image combined with some meteorological data can accurately estimate regional evapotranspiration,and the inversion result is reasonable.In this paper,six landsat8 remote sensing images from May to October 2019 are used to inverse the evapotranspiration in the chahannaor basin of Inner Mongolia,and the spatial distribution of each flux parameter and daily evapotranspiration in different phases are analyzed;At the same time,based on the remote sensing inversion results on July 14,this paper analyzes the correlation between surface temperature,albedo,specific emissivity and NDVI and evapotranspiration,and uses the geographic detector model to further explore the impact of the seven main influencing factors of surface temperature,NDVI,surface albedo,surface specific emissivity,slope,aspect and land use type on the spatial distribution of evapotranspiration in the basin.In order to more accurately analyze the water consumption of different land use types in chahannur basin,the evapotranspiration inversion results and the basin land use classification results are superimposed to further study and analyze the spatial distribution characteristics and change trend of evapotranspiration of different land use types in the basin,so as to provide a scientific basis for implementing efficient irrigation and improving the utilization rate of water resources in the basin.The main conclusions are as follows:(1)The average evapotranspiration of chahannur basin on May 27,June 28,July14,August 15,September 16 and October 2 in 2019 is inversed by SEBAL model.Generally speaking,in the area with high vegetation coverage,the evapotranspiration is relatively high,and in the area with low vegetation coverage,the evapotranspiration is relatively low;In terms of time scale,the highest value of daily evapotranspiration appeared in July and the lowest value appeared in October.(2)The P-M model is used to compare and verify the inversion results of the model.The error between the inversion value and the calculated value is less than18%.The inversion accuracy of the model is high and has good applicability.It is suitable for the calculation of evapotranspiration in arid and semi-arid areas,and can provide a reference basis for the study of water consumption of different crops in the basin;The spatial distribution trend of MOD16 evapotranspiration products is similar to that of the model inversion results,while the spatial resolution of MODIS evapotranspiration product data is small,and the calculated daily average evapotranspiration has a large error with the inversion results.It is difficult to carry out high-precision comparison and verification of the values of single-phase evapotranspiration inversion results.MODIS evapotranspiration products are more suitable for the evapotranspiration of single ground objects with aggregated distribution.(3)Among the factors affecting the evapotranspiration retrieved by SEBAL,the surface temperature,surface albedo and evapotranspiration have a negative linear correlation,and R2 are 99.27% and 98.73% respectively;NDVI,surface specific emissivity and evapotranspiration have a positive parabolic relationship,R2 are 86.66%and 93.01% respectively;Through the geographical detector model,it is found that the meteorological factors have the greatest influence on the evapotranspiration in the basin.The surface temperature and surface albedo have a great influence on the actual evapotranspiration,followed by NDVI and land use type;The terrain in the basin is relatively flat,the altitude drop is small,and the influence of topographic factors is small.(4)In the study and analysis of evapotranspiration of different land use types,it is found that the surface evapotranspiration capacity of lakes,reservoirs,pits and ponds is the largest,the evapotranspiration of the underlying surface water body of the basin is large,while the daily average evapotranspiration values of forest land,grassland and unused land are small,and the evapotranspiration capacity is relatively small.The average daily evapotranspiration of lakes,water areas,urban land and swamps is large,and the evapotranspiration of shrubs,sparse woodlands and low cover grassland is small;The better the vegetation coverage in the basin,the greater the soil humidity,the more soil water content and the stronger the surface evapotranspiration capacity. |
PDF Full Text Request