Analysis Of The Temporal And Spatial Variation Of Evapotranspiration And Its Driving Factors In Arid And Semi-arid Region Of China From 2000 To 2015

The study on the process of the terrestrial water cycle had been being paid more attention under the background of global climate change.Evapotranspiration is an important part of the process of water cycle,and it is of great significance to the energy balance and the water balance.The study of the temporal and spatial variation of evapotranspiration and its driving factors will provide an important reference for the distribution and utilization of regional water resources,the monitoring and prevention of drought and flood disasters,the protection and construction of ecology,the style of production and life and so on.The spatial and temporal variability of evapotranspiration in arid and semi-arid region of China from 2000 to 2015 was studied by using linear regression,Mann-Kendall test,Sen trend and Slope trend.Meanwhile,combining meteorological data,NDVI,land temperature,land use,GDP,population,DEM,slope,aspect and soil type,the paper studied quantitatively driving factors of evapotranspiration using the method of Pearson correlation,transfer matrix and geographical detectors.The results showed that:(1)From 2000 to 2015,the average evapotranspiration in arid and semi-arid region of China was 259.3 mm,and the evapotranspiration increased significantly.The increasing rate of evapotranspiration analysed by the linear regression and Sen trend was 1.214 mm/a and 1.2714 mm/a,respectively.The evapotranspiration of the whole region changed suddenly in 2011.(2)The average evapotranspiration decreased from the southeastern to the northwestern in arid and semi-arid areas of China.The evapotranspiration in the whole region increased from 2000 to 2015,and the area where evapotranspiration increased evidently and insignificantly was 723,300 and 929,800 km~2,respectively.Compared with the change of evapotranspiration from 2000 to 2011,from 2011 to 2015,the area where evapotranspiration increased increased,and the area where evapotranspiration increased insignificantly increased evidently.Besides,the area where evapotranspiration decreased decreased,and the area where evapotranspiration decreased insignificantly decreased evidently.(3)From 2000 to 2015,there were a significantly positive Pearson correlation between NDVI,precipitation and evapotranspiration in the whole region,and the correlation between precipitation and evapotranspiration was largest.There was a significantly negative correlation between the mean atmospheric pressure and evapotranspiration,and its correlation was largest.On the pixel scale,there was mainly a positive correlation between evapotranspiration and NDVI.The correlation between evapotranspiration and precipitation was mainly significantly positive.There were mainly an insignificantly positive correlation between evapotranspiration and mean temperature,mean water vapor pressure,mean relative humidity,mean minimum temperature.In the most area in the study area,there were insignificantly negative correlation between evapotranspiration and land temperature,mean wind speed,mean maximum temperature,sunshine hours.There was an evidently spatial heterogeneity about the correlation between evapotranspiration and mean atmospheric pressure.(4)In 2000,the average evapotranspiration about land use was forest land>construction land>cultivated land>grassland>water area>unused land.In 2010,the average evapotranspiration was cultivated land>construction land>forest land>grassland>water area>unused land.In 2015,the average evapotranspiration was forest land>cultivated land>construction land>grassland>water area>unused land.The average evapotranspiration of cultivated land,grassland,water area,construction land and unused land increased gradually from 2000 to 2015.The average evapotranspiration of woodland decreased from 2000 to 2010,but the evapotranspiration of woodland after 2010 increased evidently.(5)From 2000 to 2015,the effect of driving factor on the evapotranspiration was NDVI>precipitation>mean maximum temperature>mean temperature>land temperature>mean minimum temperature>soil type>mean relative humidity>mean wind speed>population>GDP>sunshine hours>DEM>mean atmospheric pressure>slope>mean water vapor pressure>aspect.Therefore,NDVI had a greatest impact on evapotranspiration.Precipitation,temperature,land temperature merely had a less effect than NDVI,respectively.Besides,the effects of the enhanced interaction between NDVI,precipitation and other driving factors on evapotranspiration were the most obvious.