| Abstrakt: |
Remote sensing technology has the advantages of fast, accurate, large scale, visualization which provides important imformation on a variety of water resources issues. Estimation of large-scale evapotranspiration is the most difficult part of surface water conversion. With the development of quantitative remote sensing, an effective solution has been obtained. The objective of this study was to verify the rationality of the surface energy balance algorithm for land(SEBAL)model for estimating ET on urban scale and study the temporal and spatial distribution characteristics of ET in Beijing. A total of 5 usable Landsat Enhanced Thematic Mapper satellite images( F ebruary 2, May 28, August 16, October 3, December 22, 2016) were processed to estimate surface energy fluxes and generate ET distribution maps. Results from the SEBAL model were compared with the value calculated by Penman-Monteith(P-M) equation, and a very good correlation was found between the P-M equation and SEBAL-estimated ET with a good R2 of 0.83 and a root-mean-square difference( RMSD) of 0.89 mm/d, Therefore, SEBAL has certain reliability for ET-estimation. Through the analysis of the 5 ET distribution maps, ET was higher in the northwest because of higher vegetation coverage, and it showed a very good progression of ET with time during the year of 2016, it was a single-peak distribution in a year, in various seasons, it was the highest in summer,followed by spring and auturnn, while it was the lowest in winter. Conclusion can be made that underlying surface type is one of the most important factors for affecting ET distribution in Beijing, and different meteorological factors in various seasons are the main factors for affecting ET trend in a year. [ABSTRACT FROM AUTHOR] |
