Estimation Of Evapotranspiration Using SEBAL Model In Handan Area

ET is an important process of regional water cycle and energy cycle,it has important significance to monitor and estimate regional ET,for guiding agricultural irrigation and strengthening regional water resources planning and management.This paper took Handan area as the research area,combined MODIS image data with ground observation meteorological data and DEM digital elevation data,and used the SEBAL surface energy balance model to estimate the surface ET in Handan area from 2001 to 2014.The main research contents and conclusions were as follows:Taking 2008 as an example,the temporal and spatial variation of each flux during the estimation process was analyzed.The estimated result for 2008 was validated through the measured data obtained by eddy correlation instrument,and the results showed that the SEBAL model was better estimation in Handan area.The time scale diffusion method was used to analyze the daily ET and the monthly ET based on different surface cover types.The ET of Handan area is greatly influenced by the landform..The terrain of Handan generally presents the trend of West High and East Low,the west was a mountainous area,the main land cover types were trees and shrubs,water supply was enough,and the evapotranspiration value was higher,up to about 5 millimeters per day;Central and eastern surface cover types were diverse,there were crops,urban buildings,shrubs and trees,the overall evapotranspiration was less than the western region,less than 5 mm per day..Among them,et was the highest in summer,and the lowest in winter,and the difference was very little in the two seasons of spring and autumn,which in autumn was slightly higher than in spring.Estimate the annual ET of 2001 to 2014,And carries on the time and space analysis.Annual ET of the western region with higher vegetation cover was more than500 mm all the year round;while the annual ET was less than 300 mm in the eastern and central regions.In 2001 and 2002,the average ET in Handan was basically the same,about 590 mm.while it suddenly increased to about 717 mm in 2003,and since2003 until 2014,with the expansion of the city,the residential land increased year by year,the woodland and farmland was occupied,and the surface water was gradually reduced,the overall ET showed a decreasing trend.