Satellite-based actual evapotranspiration estimation in the middle reach of the Heihe River Basin using the SEBAL method

摘要

In this study, the Surface Energy Balance Algorithm for Land (SEBAL) method from the meteorological stations and remote sensing data was used to compute the evapotranspiration (ET) rate for the middle reach of Heihe River Basin in China, in order to analyse the distribution of ET over the whole area including and surrounding the river. Energy fluxes and daily ET maps were calculated for the study area, and a number of statistics computed for each type of land cover. The results show that the ET in the study area ranged from 0 to 4.94, with an average value of 1.68 mm, on 23 September 2007. The highest ET values appeared over all types of water bodies, including rivers, reservoirs, etc., and the lowest values appeared over residential areas and in the Gobi desert. The differing values of ET for different land-cover types were due mainly to the differences in evaporative fraction. The quantity of ET was about 1.06 × 10~7 m~3 in the oasis over the course of the day, with 6.50 × 10~6 m~3 of this amount generated by farmland, approximately 61%. Micro-lysimeters were placed in the study area in 2009, in order to calculate cumulative ET over an entire growing season, in the future.