| The Kaidu-Kongqi River Basin serves as the hub of Xinjiang,from the south to the north and connecting the East and the west.With the further development of"the Belt and Road"construction,it has gradually become the main battlefield of China's oil exploration and the source of Gas Energy.However,with the rapid development of the economy,water shortage has become the main bottleneck to hold back the green economy.Evapotranspiration is the main way to transport moisture from the land to the atmosphere,and it is an important measure to definite the ecological water requirement of vegetation,which is also an important foundation for rational allocation of water resource.This paper takes the natural vegetation evapotranspiration in the Kaidu-Kongqi River Basin as a breakthrough.Firstly,using MODIS data,meteorological data and land use data,and based on SEBS model,the evapotranspiration of vegetation growing season in the study area in 2000,2010and 2017 was inverted.In addition,the temporal and spatial changes of evapotranspiration in the study area in 2010 were analyzed.The high value areas of evapotranspiration were mainly concentrated in Yanqi,Korla,Yuli and other water-rich areas in the central part of the study area.The evapotranspiration in the Kaidu River Basin changed obviously with time.The evapotranspiration in the Kongqi River Basin was seriously affected by agricultural irrigation in the central part of the study area.Secondly,according to the land use data,the natural vegetation types in the past three years were mainly forest land and grassland,mainly high-coverage grassland,accounting for 52%of the natural vegetation in the study area.Then the spatial and temporal changes of evapotranspiration in the natural vegetation growing season of the study area were analyzed.In the upper reaches of the Kaidu River Basin,due to the distribution of natural vegetation,the evapotranspiration changed more obviously,and the evapotranspiration also increased with the growth of the vegetation.The lower part of the Kongqi River Basin was mainly low-coverage grassland,and the evapotranspiration value was always low and the change was weak.Among the natural vegetation types,the high-coverage grassland was the main ecological water requirement vegetation,followed by the medium-coverage grassland and the low-coverage grassland.The average daily ecological water requirement was 0.46×10~8m~3/d,0.13×10~8m~3/d,0.10×10~8m~3/d.Because the forest area had a small distribution area it had low ecological water requirement.The average daily ecological water requirement of forest land,shrub forest and sparse forest land was 5.0×10~6m~3/d,0.3×10~6m~3/d and0.1×10~6m~3/d,respectively.Then the total ecological water requirement of each natural vegetation month was calculated,and from April to July,it is the period of time that ecological water requirement increase.From July to September it was the period of time that in ecological water requirement decline,and the ecological water requirement of all natural vegetation reached the maximum in July.The total ecological water requirement of high,medium and low coverage grassland in July was 23.17×10~8m~3,5.98×10~8m~3 and 3.88×10~8m~3,respectively.The ecological water requirement of forest land is low.The monthly average ecological water requirement of high-coverage grassland,medium-coverage grassland and low-coverage grassland was 13.71×10~8m~3,4.01×10~8m~3 and 3.05×10~8m~3,respectively.The monthly average water requirement of forest land was lower.Finally,the annual total ecological water requirement of natural vegetation in the study area in 2000,2010 and 2017 was158.07×10~8m~3,145.61×10~8m~3 and 142.19×10~8m~3,respectively.On the whole,the main natural vegetation types in the study area are grassland,and the natural vegetation area is decreasing year by year.The ecological water demand of the high coverage grassland is the largest among different natural vegetation types,and the total natural vegetation ecological water requirement in the study area is decreasing. |
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